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2.8 Erratic/high-idle Issue by ITALGT
Started on: 01-07-2015 08:42 PM
Replies: 95 (7653 views)
Last post by: 0z on 09-21-2019 11:07 PM
LornesGT
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Report this Post01-18-2015 01:45 PM Click Here to See the Profile for LornesGTSend a Private Message to LornesGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Similiar to mine but I didn't have the high idle even when cold. Light came on at idle and I could blip the throttle and light would go out. After you reset the IAC did you take it out to see how far it is extended. Have you looked at the possible reason for the 45 code on the code page. I have lost track but did you disconnect the map to see what would happen. I would get and ALDL cable and what what happens. Maybe even post a screen shoot of the info when the check engine light comes on.
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ITALGT
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Report this Post01-18-2015 02:19 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
I didn't take the IAC out after the reset, so I'll do it again and check the pintle length. I will also try unplugging the MAP. And yes, I'd like to get that ALDL cable, I can definitely see how useful it can be.

Hopefully I will have some more time to further diagnose things today.

In the meantime, here's that code 45 info from the code page for quick reference for everyone:

The ECM will set code 45 when the ECM detects a high voltage from the oxygen sensor, throttle is applied and the system is operating in Closed Loop (conditions must exist for longer than 50 seconds and engine must be running for at least 1 minute).

Check the oxygen sensor and replace if necessary.

Check fuel pressure. The system will go rich if the fuel pressure is too high.

Check for rich injectors.

Check for leaking injectors.

Check for fuel contamination (specifically for contamination with oil).

Check for proper ignition module shielding. If the ignition module is not properly shielded, the ECM might mistake the electro-magnetic interference for reference pulses, causing too much fuel to be delivered to the system.

Check the canister purge for fuel. If full, check canister control and hoses.

Check the MAP sensor. If the ECM detects a lower than normal vacuum then this will cause the system to go rich. Disconnect the MAP sensor. If the rich condition goes away, then a problem exists with the MAP sensor.

Check for leaking fuel pressure regulator by checking the vacuum line to the regulator for fuel.

Check TPS. An irregular TPS output will cause the system to go rich due to a false indication of accelerating.

[This message has been edited by ITALGT (edited 01-27-2015).]

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LornesGT
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Report this Post01-18-2015 03:30 PM Click Here to See the Profile for LornesGTSend a Private Message to LornesGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
I was going to try this myself if my idle didn't get fixed: instead of taking out the IAC I thought I could use a paper clip or something to stick in the hole and angle toward the pintle to see if it was closed after the reset. I don't know if anything can be fanagled in there.
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ITALGT
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Report this Post01-18-2015 05:16 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Here's my current breakdown of that code 45 list:

Check the oxygen sensor and replace if necessary.

The O2 sensor was changed not long ago and replaced with a non-Bosch unit (I keep hearing that Bosch injectors are notorious for causing problems in a Fiero).

On a side note, I read somewhere that if the O2 sensor doesn't have a good ground, it can lead to a lower voltage reading to the ECM... which can cause false O2 readings. While I was installing the injectors, I also added another ground from the back side of the block to the firewall on the driver side; the original ground strap from the engine to the deck lid hinge had been cut at some point and was never reinstalled. I also cleaned up the passenger side engine ground mounting point from the battery (the one that's oh-so-fun to get at between the engine and firewall). Could this be why the code 45 suddenly appears now after the I put everything back together with new injectors and even more clean grounds? That said, it doesn't make sense that the exhaust smells normal after the injectors were installed, yet the O2 sensor suddenly thinks the engine is running rich.

Check fuel pressure. The system will go rich if the fuel pressure is too high.

Haven't done this yet. I was so close to replacing the fuel pressure regulator while I had the intake off just as a precaution, but I elected not too. It's not hard at all to remove the upper intake for access to the regulator, so no big deal if it needs to be done at some point. However, I do need to get the fuel pressure checked so I can officially scratch this one off this list.

Check for rich injectors.

Injectors are replaced by stock rebuilt units and the engine runs awesome now despite the high idle and code 45. While the idle is now super steady at 1500 RPMs, the code 45 suddenly pops up and the idle gets erratic at 1300-1500 RPMs... or so. When the revs are increased, the check engine light (code 45) goes away. Let it back down to idle a minute or so and the code pops up again along with the crappy idle. The engine doesn't act like it's running rich; exhaust fumes are now minimal compared to before the injectors were replaced. I don't think "rich injectors" are the problem.

Check for leaking injectors.

Fairly confident at this point that this one can be ruled out, unless the cold-start injector was leaking (stuck open). I don't think it's the problem, since I've disconnected the switch and crimped the fuel line with vise grips (twice for good measure). No change.

Check for fuel contamination (specifically for contamination with oil).

Fuel contamination? As far as the oil goes, the freshly-changed 10W-30 Havoline oil with a couple hundred miles on it looks and smells fine. The old oil I drained before changing injectors? Not so much. Pretty stinky.

Check for proper ignition module shielding. If the ignition module is not properly shielded, the ECM might mistake the electro-magnetic interference for reference pulses, causing too much fuel to be delivered to the system.

Now, this one has me stumped. I don't see a "shield" anywhere near the module on my Fiero. Could this be because it's actually missing? I searched around a bit on the 'Net for a picture, but didn't have much luck. Can anyone clear this up with a pic???

Check the canister purge for fuel. If full, check canister control and hoses.

Checked the canister a while back but there was no fuel. I suppose I could check it again, but I don't think this is the problem.

Check the MAP sensor. If the ECM detects a lower than normal vacuum then this will cause the system to go rich. Disconnect the MAP sensor. If the rich condition goes away, then a problem exists with the MAP sensor.

Did this... finally. The MAP sensor is new and the vacuum line running to it is secure/leak free. I disconnected the MAP pigtail and started the engine... immediately got a check engine light with poor idle. Turned engine off and reinstalled the MAP pigtail; started engine again, check engine light disappeared and idle returned to being stable. I think this one can also be taken off the list.

Check for leaking fuel pressure regulator by checking the vacuum line to the regulator for fuel.

Had this line off a few times in the past month, never had fuel in it.

Check TPS. An irregular TPS output will cause the system to go rich due to a false indication of accelerating.

The TPS is new, however I haven't verified voltage; there is a strong possibility that the pigtail is bad and needs to be replaced. I have a new one ready to be installed as soon as I can find the time.

The adventure continues!

[This message has been edited by ITALGT (edited 01-19-2015).]

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Patrick
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Report this Post01-18-2015 11:49 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by ITALGT:

I have ordered rebuilt and flow-matched fuel injectors from Precision Auto Injectors located right next door in Orlando, FL. The current advertised price for the set is $89.99 plus shipping and Florida sales tax. I found the discount code "jeep" online and got $9 off my order. Total shipped: $94.28... not bad at all. Note: for a little more money (about $125) you can buy brand new injectors (non-AC Delco). I may have spent the extra money if RockAuto had enough of one of the cheaper X-Brands in stock... but they didn't at the time. These rebuilt units will do the job just fine... there is a ton of great online reviews for this company, and the injectors come with a one year warranty too:

Precision Auto Injectors


 
quote
Originally posted by ITALGT:

BIGTIME improvement with the exhaust smell, much less potent. That's actually one of the very first things I noticed after starting it up.


I'm hoping new injectors will also correct the issue my Fiero has with really stinky exhaust. Otherwise the car runs great. I want to see if I can cure most of this problem before I put a new cat on (otherwise the cat may quickly burn itself out in short order).

I just ordered a set of these fuel injectors for my Formula - total price (with discount and including shipping to WA)... $77.20 Not too shabby. And no cores are required to be returned.

Sale ends in ten minutes. Seriously.

[EDIT] Sorry, the extra special sale price of $76.95 is now over. It's back up to the usual sale price of $89.99, marked down from the "regular" price of $99.95

[This message has been edited by Patrick (edited 01-19-2015).]

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ITALGT
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Report this Post01-19-2015 07:42 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Nice... sounds like you scored. I'm curious what kind of results you have after the injectors are put in.

I'm glad I did the injectors... worth every penny. Yes, the high idle is still there, but it's much more stable now and the driveablility, throttle response and overall power improvement has been undeniable. Exhaust fumes are ridiculously low now compared to before the install. I can actually run the car now in my partially opened garage without an issue, where as before if I let the engine run for a few seconds (even WITH the doors wide open) I would quickly be overwhelmed by fumes. My wife would even complain about the odor inside the house. My clothes would stink because of it afterwards it was so bad.

Not any more... which is why I'm puzzled as to why the code 45 (rich condition) suddenly appears.

Tonight I ordered the correct GM style IAC/MAP/TPS pigtails from The Repair Connector Store. The first ones I ordered were female pronged, not male... so I need to return them. The 4-way EGR solenoid connector is still evading me; I may end up having to make one, which means buying the shell, prongs and pliers to do it. If I can just find an assembly that's ready to splice in, I'll be happy.

Since the IAC, CTS and TPS are all new, I really want to get those old/ratty pigtails replaced and see what happens to the idle.

Also need to check the fuel pressure and timing to see where it's at.

I finally placed the order for the MSD coil/cap/rotor/harness and Taylor spark plug wires today. I can't wait to replace the old factory coil and cheesy el-cheapo cap/rotor/wires with good the good stuff.

Stay tuned!

[This message has been edited by ITALGT (edited 01-30-2015).]

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Patrick
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Report this Post01-19-2015 08:16 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by ITALGT:

Nice... sounds like you scored. I'm curious what kind of results you have after the injectors are put in.


It may be a month or so before I actually swap out the injectors, but I'll certainly let you know here how it goes.

By the way, thanks for the link to the injector site. I'm always leery, but if the injectors all turn out to be properly rebuilt and functional, I probably got a heck of a deal.

 
quote
Originally posted by ITALGT:

Also need to check the fuel pressure and timing to see where it's at.


My experience with a lot of cars over the years is that engine idle speed will continue to increase (up to a certain point) as ignition timing is advanced. Yes, the IAC (on a fuel injected engine) will usually be able to bring the idle speed down (to compensate), but it can only reduce it so much. It's possible (if you haven't checked your ignition timing) that it's simply too far advanced. Ordinarily, you'd probably also hear the engine "pinging" when accelerating under these conditions... but not being there myself, I don't know what all you're dealing with.
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ITALGT
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Report this Post01-19-2015 08:31 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

My experience with a lot of cars over the years is that engine idle speed will continue to increase (up to a certain point) as ignition timing is advanced. Yes, the IAC (on a fuel injected engine) will usually be able to bring the idle speed down (to compensate), but it can only reduce it so much. It's possible (if you haven't checked your ignition timing) that it's simply too far advanced. Ordinarily, you'd probably also hear the engine "pinging" when accelerating under these conditions... but not being there myself, I don't know what all you're dealing with.


You are very welcome, I'm glad I can help you and any other Fiero owners out.

I never dealt with Precision Auto Injectors before this; before placing the order, I did a little research on them an discovered one great review after another. They've even been mentioned a few times on this forum, but didn't know about it until after I bought them.

The injectors I received were nicely packaged and exactly the same style as the original injectors that I removed from the engine. Great price compared to new, one year warranty, no cores to deal with, and very fast shipping too. A+ to these guys. I think you'll be happy.

The timing. Yes, I hear you loud and clear, because the previous owner installed the new distributor and set the timing... not me. I have no idea what the timing was set at. The fact that the distributor was replaced raises that red flag up real high. This is definitely on the to-do list... if I had my own timing light, it would have been done a long time ago. As far as pinging goes though, I haven't heard it once. But then the muffler has one big gaping hole in it right now, so pinging might not be very audible due to the loud exhaust.

A new muffler is on my list too.

And the story continues...

[This message has been edited by ITALGT (edited 01-19-2015).]

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Report this Post01-19-2015 09:04 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by ITALGT:

...if I had my own timing light


Ya gotta buy a timing light.

Seriously, no one who works on their Fiero should be without one. You really can't start trying to troubleshoot an engine issue without something as basic as ignition timing being set correctly.

I picked up a decrepit looking timing light on eBay for next to nothing... but it does the trick!
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ITALGT
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Report this Post01-19-2015 09:20 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

Ya gotta buy a timing light.

Seriously, no one who works on their Fiero should be without one. You really can't start trying to troubleshoot an engine issue without something as basic as ignition timing being set correctly.

I picked up a decrepit looking timing light on eBay for next to nothing... but it does the trick!


Trust me, I know.

Every timing light that I've owned was at some point lent out and then broke... or never returned.

The next one I get my hands on is going to be locked up at home for my eyes only.

[This message has been edited by ITALGT (edited 01-19-2015).]

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ITALGT
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Report this Post01-20-2015 05:55 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Small update...

I've been putting some more miles on the Fiero. As the computer has been learning it's new parameters, it seems to be running better and better.

Hopefully I can get the timing and fuel pressure checked in the next day or two. I will be spending my weekend at the Rolex 24 race in Daytona, so I'm not sure I will get it done this week or not.

Stay tuned.

[This message has been edited by ITALGT (edited 01-20-2015).]

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Report this Post01-20-2015 08:25 PM Click Here to See the Profile for countach711Click Here to visit countach711's HomePageClick Here to Email countach711Send a Private Message to countach711Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by ITALGT:

Small update...

I've been putting some more miles on the Fiero. As the computer has been learning it's new parameters, it seems to be running better and better.

Hopefully I can get the timing and fuel pressure checked in the next day or two. I will be spending my weekend at the Rolex 24 race in Daytona, so I'm not sure I will get it done this week or not.

Stay tuned.



that's funny, I took my Fiero on it's longest ride today too, and like you despite the new injectors having REALLY solved the rough and stumble issues, it was idling pretty high. Anyway, on the way back, I noticed the idle was down where it should be, I guess the computer just takes a little time and travel to learn the proper idle speed.
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Report this Post01-21-2015 06:50 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by countach711:


that's funny, I took my Fiero on it's longest ride today too, and like you despite the new injectors having REALLY solved the rough and stumble issues, it was idling pretty high. Anyway, on the way back, I noticed the idle was down where it should be, I guess the computer just takes a little time and travel to learn the proper idle speed.


I know that the engine should run better as some miles are put on, but the high idle issue I've been having remains constant. We've been having some cooler weather lately here in Florida... the last few days the cold start idle has been really high at about 2500 RPMs and slowly drops back down to 1500 RPMs when warmed up. Whatever the problem is, I know it's at least related directly or indirectly to temperature change.

[This message has been edited by ITALGT (edited 01-21-2015).]

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Report this Post01-24-2015 09:16 AM Click Here to See the Profile for YannskyClick Here to Email YannskySend a Private Message to YannskyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hi
I don't know if could be related but i read something on the egr solenoid and rough idle. Did you test yours?
There is a couple threads on that.

After reading your thread, at this point nothing to lose!
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Report this Post01-24-2015 01:09 PM Click Here to See the Profile for darbysanClick Here to Email darbysanSend a Private Message to darbysanEdit/Delete MessageReply w/QuoteDirect Link to This Post
On my TPI setup in my Elky, whenever I set my IAC, I have to re-set my TPS. I find this is an iterative step- sometimes two or three times, to get both happy. When you went back and opened up your base idle adjustment screw, you may have gotten them all out of "alignment" again. I would set the IAC as before, with re-setting the base idle adjustment, and then set the TPS.

------------------
'87 GT in process!

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ITALGT
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Report this Post01-27-2015 07:26 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Yannsky:

Hi
I don't know if could be related but i read something on the egr solenoid and rough idle. Did you test yours?
There is a couple threads on that.

After reading your thread, at this point nothing to lose!


I found a really good deal on a new AC Delco solenoid, so I just replaced the original. That said, the EGR solenoid 4-way connector has a bulge on the bottom ground pin that prevents it from seating good. It's being pushed a little out the back of the connector, so I'm sure that there is still contact between the pins. I haven't been able to find a replacement pigtail for it yet. So far, all I can find is the components to assemble one... which means buying a special weather pack crimping tool to do the job.

It's on the list.

 
quote
On my TPI setup in my Elky, whenever I set my IAC, I have to re-set my TPS. I find this is an iterative step- sometimes two or three times, to get both happy. When you went back and opened up your base idle adjustment screw, you may have gotten them all out of "alignment" again. I would set the IAC as before, with re-setting the base idle adjustment, and then set the TPS.


I did measure the TPS voltage... it was 0.21 volts. According to what I've read, the TPS works best with under 1 volt... some recommend 0.5 to 0.6 volts, so I tweaked the TPS lever a bit to get in that range and final setting now is 0.54 volts. No change in idle afterwards. Before I go any further with another IAC reset, I am going to get the timing fine tuned and fuel pressure checked. And then there's the distributor issue I'm questioning too...

I took the distributor cap off for closer inspection. First thing I noticed is that there is a good amount of vertical play in the shaft. This is a new distributor installed by the previous owner, and it looks like they didn't bother using washers to eliminate the end play. I can only imagine that the timing and idle is affected by this slop. When I get the new MSD/Taylor components, I will remove the distributor and shim it accordingly. I'll also install a new Delco ICM and heat sink... while I am at it, and replace the pigtails too. I will use the old (well, fairly new) ICM for my on-board back-up.

Man this thing is like opening up a can of wiggly worms.

Sooner or later I'll find that mystical 900-1000 RPM 2.8 Fiero idle if indeed it exists.

Stay tuned...

[This message has been edited by ITALGT (edited 01-27-2015).]

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Report this Post01-27-2015 08:08 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
On a related side note... I'm beginning to wonder if the relatively new-looking catalytic convertor installed by the previous owner is fried and possibly causing issues. I want to replace it with a straight pipe or a glass-pack anyway... so that will happen soon along with a new muffler to replace the blown-out original.
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Report this Post01-27-2015 10:07 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
I played with the Fiero a little more tonight.

The idle screw is set back to it's original factory location now and I did a full IAC test and reset. The IAC is working just fine. The throttle plate is fully closed and engine will not run with the IAC fully extended.

After returning the idle screw back to the factory setting, I readjusted the TPS to 0.6x volts. The engine runs better now, mainly because the idle screw is back to it's original position, allowing the throttle plate to fully close (without binding). I'm not sure raising the TPS voltage had anything to do with it, but at least I know it's in the proper recommended voltage range.

My ears detect a miss. It's not noticeable under acceleration, but at idle and cruising speed I'm sensing it. This could explain the code 45 (O2 sensor reading rich) at idle, and not under higher RPM conditions. As I previously mentioned, there may be an ignition issue here that I've overlooked.

I manually advanced the timing until I heard a very slight pinging under load, then backed it off a bit until the pinging went away. The idle did not change with any adjustments made with the base timing, and appears to have been set correctly by the previous owner. I will fine-tune it with a vacuum gauge at some point, but I'm confident that it is set very close to where it needs to be for now.

Moving forward, I am now going to focus on the ignition components, since that is where the obvious problems seem to be. Fuel pressure test will also be next.

Good times!

[This message has been edited by ITALGT (edited 01-27-2015).]

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Report this Post01-30-2015 06:33 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
The old/beat-up TPS, IAC and MAP sensor pigtails are now replaced with new. I completely soldered every splice and used heat shrink tubing to protect them.

So far, these are the GM-style pigtails that I have confirmed to fit properly on a 2.8 Fiero:

Pico #5612C - IAC Valve
Pico #5613C - MAP Sensor
Pico #5617C - TPS

These can all be bought fairly cheap, along with other GM-style pigtails, from The Repair Connector Store.

Please note, these are not "restoration quality" connectors, as most of the wires are not color coded like O.E.M. For instance, every one of the IAC pigtail wires are black (no color coding or stripes whatsoever)... and the MAP sensor pigtail shell is green just like O.E.M., but the wires are white (the TPS pigtail has all white wires too). No big deal if one pays attention to which wires go where before pemenantly splicing them in. The new connectors fit tight and snug like O.E.M., which is really the important thing. If the different colored wires are too much of an eyesore (especially the white ones), they can easily be covered up with some black plastic wire loom... no big deal.

I also messed with the EGR solenoid connector, and finally got the ground pin straightened and properly seated into the solenoid receptacle. Upon closer inspection, the CTS pigtail also needs to be replaced (it literally started to crumble apart in my fingers). I tweaked the prongs a bit so they at least fit snug now on the CTS. I also cleaned and inspected the various harness connectors for the ignition system and reset the IAC again... all of this and still no changes in idle.

It looks like I did find and fix one issue though... the vacuum hoses going to the fuel vapor canister somehow got reversed the last time I messed with them (about the time I installed the new injectors). I switched the hoses back around, and so far the code 45 is gone when idling.

Tomorrow I want to test the fuel pressure and set the timing with a vacuum gauge. The MSD cap/rotor/coil and Taylor spark plug wires haven't arrived yet, when they do I'll yank out the distributor and replace the ICM with a Delco unit, replace all ignition harness pigtails, and reinstall the distributor with the appropriate spacer washers to eliminate the excessive vertical play in the shaft.

With all that being said, I think at this point that if I found the fuel pressure (regulator) to be the cause of the high idle, I would be soooooo relieved. At least then I'd know exactly what to do and have it fixed within a few hours time.

Stay "tuned."

[This message has been edited by ITALGT (edited 01-31-2015).]

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Report this Post01-31-2015 02:14 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Update...

I fine tuned the timing with a vacuum gauge, and I did in fact have it set very close to optimum. Good there.

Fuel pressure test revealed what may be the source of this high idle and code 45 (running rich) at idle. Yes, the check engine light is unfortunately back when the engine sits and idles.

Fuel pressure with the ignition key on/engine off shows 20-22 lbs. The correct range is 42-47 psi. Whoa Nelly.

With the engine running at idle, fuel pressure goes to 38-40 lbs... from my understanding, the proper range is 35-40 lbs. So while idling, the fuel pressure seems to be right . After shutting down the engine, the psi drops fairly quickly to about 22 lbs. and drops pressure very slowly afterwards. Very strange.

I'm off to pick up a new regulator here shortly, if all goes well I will have it installed by this evening. With the psi readings being off track, I suspect something is in fact up with the regulator. I will report back with the results.

I just hope it's not the fuel pump going bad.

[This message has been edited by ITALGT (edited 01-31-2015).]

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Report this Post02-01-2015 04:44 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Ok, fuel pressure regulator is now in. I also put in a new fuel filter, although the old one I replaced was practically new from the PO...

Fuel pressure now reads over 45 psi when the fuel pump is cycled on. It holds there then drops steadily after the pump shuts off. Now for the first time the engine acts like it's trying to idle down below 1500 RPMs but just about dies before jumping back up. I readjusted the throttle blade again from the stock position just to temporarily keep the engine from dying when coming to a stop... but something else is up here that's really messing things up.

That intermittent "miss" I was experiencing before has turned into random "bucking" while driving. It's still not there under hard acceleration though. It's become bad enough that I'm scared to drive it. I know the distributor was replaced by the previous owner, but I honestly don't know what brand it is or if it was a rebuilt unit or new. I know bad ICM could cause all sorts of issues, but that's just one thing on a long list of possibilities here. Bad fuel pump? Bad ground from the fuel pump? Ignition coil? Bad ignition connection? I don't know... I've taken the plugs out a couple times now for inspection, but no single plug looks any different than the others (clean with only a little soot). That's what leads me to believe that the problem might not be a bad cylinder, but a random fuel delivery issue or ignition issue.

One more note, I do notice a lot of oil making it's way through the PVC and EGR system into the intake. What causes this besides bad piston rings and/or valve seals (cylinder blow-by)?

I am going to be honest here, this is turning into a much bigger project than I ever anticipated and I am getting really frustrated with it. This 2.8 is killing me... I have bigger fish to fry (a V8 fish).

HELP with ideas, anyone??? I sure do miss carburetors. This is getting ridiculous!

[This message has been edited by ITALGT (edited 02-01-2015).]

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Report this Post02-01-2015 06:16 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by ITALGT:

I fine tuned the timing with a vacuum gauge, and I did in fact have it set very close to optimum.


I'm not looking for an essay , but I'm curious how you do this.

Anytime I've tried to time an engine (going back over 40 years) using a vacuum gauge (and seeking the highest vacuum), the timing ended up being too far advanced when driving under load. Instead I time by "ear" (flooring it in 4th gear while going up a hill, and backing off the timing if I hear pinging), and I find this method to be much more reliable (although the "smoothness" of the idle will sometimes be sacrificed at this increased level of ignition timing in the quest for maximum power).

[This message has been edited by Patrick (edited 02-01-2015).]

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Report this Post02-01-2015 07:36 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

I'm not looking for an essay , but I'm curious how you do this.

Anytime I've tried to time an engine (going back over 40 years) using a vacuum gauge (and seeking the highest vacuum), the timing ended up being too far advanced when driving under load. Instead I time by "ear" (flooring it in 4th gear while going up a hill, and backing off the timing if I hear pinging), and I find this method to be much more reliable (although the "smoothness" of the idle will sometimes be sacrificed at this increased level of ignition timing in the quest for maximum power).



You hit the nail on the head, really. I tried to keep this short... I really did!

From what I understand reading up on the subject, using the highest vacuum reading to set the timing is in fact incorrect, and will set the timing too far advanced just as you have experienced. If fact, I did this by accident the first time and that's exactly the case. Engine ran, but when I shut if down and tried to start it again, I could tell the starter was struggling a bit to turn over the engine. It was obvious the timing was too far advanced and I had forgotten one little detail...

Somewhere on the Interweb I read that the proper amount of vacuum is to set the timing is at about 2" from the highest reading (mine was at about 20", so I retarded the timing until it came down to about 17-18"). The results I got seemed to be consistent with that information, but don't hold me to it for every engine. Normal 2.8L vacuum at idle should be 16-18", so it sure seems logical. The engine ran fine afterwards, no pinging good power and easy starting.

That being said... I've done this manually a few times too. I advanced the timing until there was ever so slight pinging under load, then I retarded the timing a couple times in very small increments until the slight pinging went away. No real noticeable difference between the vacuum gauge setting and using the old school method to be honest. A timing light really is the only good way to "fine tune" the timing to within a degree or two... that's really what it boils down to. At least now I am confident it's set very close to where it should be, I'll hit it with one of those fancy lights at a later date.

Fuel pressure appears normal now that the regulator was replaced. It does seem to drop fairly quickly after the fuel pump stops. Is this normal? I'm going to focus on the ignition system now to hunt for the engine miss/bucking I'm experiencing.

And of course, if anyone has ideas what I'm dealing with here, feel free to chime in at any time. I am pulling the plugs again tonight for yet another inspection.

Engine's not pinging now and starter turns easy with no struggling. It even seems to pull strong under load on all cylinders. The intermittent miss I am getting seems to happen only at cruising speed and at idle. The engine randomly bucks and jerks until I start accelerating or downshifting. That about sums it up really!

[This message has been edited by ITALGT (edited 02-01-2015).]

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Report this Post02-01-2015 08:49 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by ITALGT:

A timing light really is the only good way to "fine tune" the timing to within a degree or two... that's really what it boils down to.


The funny thing is... I look at it completely opposite of that. I use the timing light to set the ignition advance to factory specs, and then I time the ignition by "ear" to maximize the advance for my particular engine.

 
quote
Originally posted by ITALGT:

Fuel pressure appears normal now that the regulator was replaced. It does seem to drop fairly quickly after the fuel pump stops. Is this normal?


In my experience... no, it is not "normal" for the fuel pressure to rapidly drop when the pump stops. Leaky injectors? Rotted (or loose) short section of hose in the tank?
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Report this Post02-01-2015 11:13 PM Click Here to See the Profile for LornesGTSend a Private Message to LornesGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Cant say I have driven mine enough to oil up the pcv but maybe yours is not closing but on the other hand I had a weird idle because the tube into the PCV was blocking the elbow and not relieving pressure.

You said that disconnecting the MAP made the engine idle bad. When I was testing mine died only once but I think when I blocked of the EGR tube it didn't die. I had since tried it again with the EGR connected and it idled the same for me under a cold idle. I will have to try again but I won't be able to until the weekend.

[This message has been edited by LornesGT (edited 02-01-2015).]

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Report this Post02-02-2015 09:46 AM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks for the help guys... this has turned into quite the adventure. I'm going to take a peek at that PVC tube that goes into the valve; I'm curious if I have the tube jammed in too far causing a blockage. If that's what's causing the excessive oil getting into the intake, I'd be very happy.

I pulled the plugs again last night and once again found normal/clean electrodes with no obvious fuel smell or fouling. There is some black soot in the bases, but the tips are all greyish-white and clean. Whatever the cause of the random miss is, it appears to be affecting all cylinders, not just one. The code 45 rich condition still pops up after a short time idling, too much fuel is coming from SOMEWHERE or not getting burned. Fuel pressure is normal now that I replaced the regulator, but drops fast after the pump shuts off, as if there is a leaking injector. Since the fuel injectors were just replaced I am going to rule them out as the issue.

At this point, there's only one thing left that seems logical if it's fuel related; a leaking cold start injector. This would affect all cylinders, especially at idle. A few weeks ago, I pinched the supply line and unplugged the CSI from the harness, but I'm thinking that fuel could still be getting through to the injector and into all cylinders. It's time for this thing to go.

My MSD cap/rotor/coil and Taylor wires have finally arrived, so I will try installing those tonight and gap the plugs to 0.60 while I'm at it. Once I get a few things I need for the CSI delete, I'll yank the distributor out and take care of business (probably this weekend).

The adventure continues!

[This message has been edited by ITALGT (edited 02-02-2015).]

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Report this Post02-02-2015 10:32 AM Click Here to See the Profile for LornesGTSend a Private Message to LornesGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by ITALGT:

Thanks for the help guys... this has turned into quite the adventure. I'm going to take a peek at that PVC tube that goes into the valve; I'm curious if I have the tube jammed in too far causing a blockage. If that's what's causing the excessive oil getting into the intake, I'd be very happy.

I pulled the plugs again last night and once again found normal/clean electrodes with no obvious fuel smell or fouling. There is some black soot in the bases, but the tips are all greyish-white and clean. Whatever the cause of the random miss is, it appears to be affecting all cylinders, not just one. The code 45 rich condition still pops up after a short time idling, too much fuel is coming from SOMEWHERE or not getting burned. Fuel pressure is normal now that I replaced the regulator, but drops fast after the pump shuts off, as if there is a leaking injector. Since the fuel injectors were just replaced I am going to rule them out as the issue.

At this point, there's only one thing left that seems logical if it's fuel related; a leaking cold start injector. This would affect all cylinders, especially at idle. A few weeks ago, I pinched the supply line and unplugged the CSI from the harness, but I'm thinking that fuel could still be getting through to the injector and into all cylinders. It's time for this thing to go.

My MSD cap/rotor/coil and Taylor wires have finally arrived, so I will try installing those tonight and gap the plugs to 0.60 while I'm at it. Once I get a few things I need for the CSI delete, I'll yank the distributor out and take care of business (probably this weekend).

The adventure continues!



I could be wrong but I think the gap is .45. Soot is at the base of the threads? That ALDL cable will really help, I know OK dad, but you will see the readings or someone here better than I will if you post them.
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Report this Post02-02-2015 12:02 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
There's black soot on every plug in the bases around the insulator, but not on the upper portion of the insulator or electrodes. It looks consistent with the random misfire/rich condition I'm experiencing... and again, all plugs looked the same and none of them reeked of fuel.

Yes, 0.45 is correct plug gap when using a stock ignition coil. With a hotter ignition coil, good cap/rotor and 8mm wires, you can safely go up to 0.60. I will start there, and gap them less later if needed.

And that cable. I'm going to get one right after this last hunch is proven wrong!

[This message has been edited by ITALGT (edited 02-02-2015).]

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Report this Post02-02-2015 09:15 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
The cold start injector is disconnected and sealed at the fuel rail with a M12 x 1.25 oil plug... I haven't removed the injector itself yet, I will do that when I pull the distributor.

No change in the idle condition or random miss.

MSD cap/rotor/coil and Taylor Spiro Pro 8mm wires were then installed. Definitely woke up the engine. But...

No change in the idle condition or random miss.

I removed the NGK's and replaced them with the fairly new Delco's I took out right after I bought the car. I gapped them at 0.60 and guess what...

No change in the idle condition or random miss.

And here's what I found when I pulled the NGK plugs; spark plugs from cylinders 1, 2, 4, 5 and 6 are getting dark and carbon fouled from burning rich. Cylinder #3 spark plug is as clean as a freakin' whistle... no carbon, the insulator is white, and it looks like new compared to the other five. I just pulled these out days ago and they were fairly clean and normal looking. It seems the new regulator and proper fuel psi has affected the problem drastically. WTF.

I need a break now.

Discuss.

[This message has been edited by ITALGT (edited 02-02-2015).]

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Report this Post02-03-2015 09:46 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
I see the discussion got rather heated.

I am starting to wonder if buying this Fiero was a good idea. I expected a few problems here and there, but this has become WAY too much of a hassle for a married man with a full time job, kids and a wife. I've spent weeks upon weeks working on it, diagnosing, fixing and replacing this and that... and now it's running worse than when I bought it.

I appreciate those of you have taken the time to help me... I'm not giving up, but sooner or later somthing has to give. This is my daily driver car that I rely on to get to and from work. If I can't get this engine running right soon, I'll have to hand the torch over to someone who can, as I just don't have the time or money. My V8 project is my priority and where I need to be focusing my efforts... not this.

Stay tuned... or not. Whatever.

[This message has been edited by ITALGT (edited 02-08-2015).]

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Report this Post02-07-2015 10:31 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Update... I took a much needed break from all this, as I was obviously getting very frustrated. I'm feeling much better now... back to work.

The random miss/bucking issue is becoming worse and I've got a hunch as to why.

The fuel pressure is fine when the pump cycles, then rapidly falls when it stops running. Following the diagnosis procedure in the Pontiac service manual, I now know that there is at least one of the following; a leaking fuel pump coupling hose, a leaking pulsator, or a faulty fuel pump... although at this point I highly doubt it's the pump.

When I changed the fuel filter a week or two ago, I let the filter back-flush/drain into a clear plastic cup to see how it looked. I noticed blackish tint to the fuel. The filter was fairly new from the PO, so this looked suspicious to me.

After doing some research, I discovered that most new fuel pumps come with a little 3" or so rubber hose to replace the pulsator. This rubber hose has been well documented to deteriorate into black jelly-like mush which eventually evolves into a fuel pressure leak. Now the blackish fuel that came out of the filter might actually make sense.

Here's a short YouTube video that buddycraig posted showing the potential issue:



My guess is that at some point a new pump was installed with this crappy rubber hose in place of the pulsator... and it's now falling apart. That would explain the blackish colored fuel from the filter and why the random miss/rich condition is slowly escalating; the leak, wherever it is, is slowly getting worse. Whatever the case turns out to be, I know I have a rapid fuel pressure leak in the tank and it has to be fixed... so that's what's up next.

Today I ordered a new Bosch fuel pump from RockAuto. I will also be getting some submersible 30R10 fuel line hose from NAPA (#H209) along with some F.I. clamps to replace the standard rubber line that's supplied with the pump. The H209 hose is 5/16" in diameter but 1' long... WAY more than I will ever need, and costs about $30... but that's what I have found so far. I'll report back if I find a cheaper route to go.

Time to drop the tank!

Hopefully I can get the new pump installed by next weekend.

[This message has been edited by ITALGT (edited 02-08-2015).]

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Report this Post02-07-2015 10:50 PM Click Here to See the Profile for LornesGTSend a Private Message to LornesGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Well I'm glad you posted that info! I have a fuel pump to put in for my 3800 eventually.

[This message has been edited by LornesGT (edited 02-07-2015).]

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Report this Post02-08-2015 11:04 AM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
That's good to hear.

I like to post everything I can about what I've been learning in the hopes that others might benefit. I originally started this thread because I thought I was overlooking something simple, and figured with help from the forum I'd have it fixed in no time. That was obviously not the case; as it turns out there have been multiple issues that have contributed to the actual problem(s), making it more than a little difficult to diagnose.

So many of these types of threads have been started only to be later abandoned by the topic starter after he/she gave up trying to fix the problem, or they fixed the problem but never bothered to report back with the solution. I don't care how many posts it takes to get there, but at some point this thread will end with a V6 Fiero that idles and runs like it should, along with the information on how it was finally fixed.

Notice I didn't say what size V6 Fiero.

Stay "tuned."

[This message has been edited by ITALGT (edited 02-09-2015).]

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Report this Post02-15-2015 06:50 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Can anyone tell me what can cause the throttle position sensor voltage to be low?

I replaced the TPS and TPS pigtail not long ago. Voltage read normal and everything was fine for a while. Now all of a sudden I am getting a code 22 for low TPS voltage. I checked the TPS voltage and now it's 0 when fully closed, and climbs to only 0.05 when at WOT. The supply wire is also only showing 0.05 volts.

I wiggled the wires and connections around but noticed no change in voltage. When I installed the pigtail, all connections were soldered and shrink wrapped.

Where is the power supply wire located that feeds this circuit? BTW, I recently cleaned the C500 contacts as well.

I'm stumped... any ideas out there?

[This message has been edited by ITALGT (edited 02-15-2015).]

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Report this Post02-15-2015 11:24 PM Click Here to See the Profile for LornesGTSend a Private Message to LornesGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Diagram in this thread. Looks like PCM sends the voltage so probably a bad wire.

http://www.fiero.nl/forum/A...130314-1-086898.html
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Report this Post02-16-2015 12:05 AM Click Here to See the Profile for fieromattyClick Here to Email fieromattySend a Private Message to fieromattyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Maybe check the starter solenoid? Make sure the connections are good. Mine was loose and caused a weird missfire. Drove me crazy for weeks.
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Report this Post02-16-2015 08:23 AM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by LornesGT:

Diagram in this thread. Looks like PCM sends the voltage so probably a bad wire.

http://www.fiero.nl/forum/A...130314-1-086898.html


Nice, thanks for sharing. This diagram also confirms I the TPS pigtail is wired correctly too. Per advice from a fellow forum member, I am going to dig into the harness to find where the TPS power supply splices into the MAP power supply. There may be a loose or corroded connection.
 
quote
Originally posted by fieromatty:


Maybe check the starter solenoid? Make sure the connections are good. Mine was loose and caused a weird missfire. Drove me crazy for weeks.


Last weekend while the car was up on jack stands for a new fuel pump, I took the time to clean and inspect the starter/solenoid connections as best as I could. They were dirty and not very tight, but unfortunately there wasn't any change after they were cleaned. Here's the kicker though. Over the past couple months now, the starter has been acting up. Most of the time it turns the engine over just fine, but every now and then it struggles terribly. It kinda' acts as if it's turning over an engine which has it's timing is too far advanced (it's not), or as if it's just not getting enough juice to crank.

I am beginning to wonder if the low voltage at the TPS is directly related to the problem I am having with the starter. Maybe a random short or bad ground in the solenoid or starter could cause this erratic bucking/misfire/rich condition with low TPS voltage? That would certainly explain why I still have the current symptoms.

Anyone have any thoughts about this? Low TPS voltage... erratic bucking and misfire... excessively rich condition... starter occasionally struggling...

[This message has been edited by ITALGT (edited 02-16-2015).]

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Report this Post02-16-2015 05:29 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Ok, the low TPS voltage problem has now been fixed. The ECM grounds to the engine block were a little loose and caked in dirt/oil. After cleaning everything up good, the code 22 is gone and the TPS voltage is back to normal.

I was really hoping that I discovered the cause of all my issues with these loose/dirty ECM grounds, but ultimately there was no change in the misfire/bucking/rich condition.

The new Bosch fuel pump was installed a week ago. The one in the tank was the original Delco, and it obviously was due for replacement. Small bits of black rubber and/or plastic were starting to come out of the pump. The sock was completely black and clogged, and it was also collapsed onto the pump inlet. The pulsator was still there, and I replaced it with the submersible fuel hose. The tank itself looked really clean with no signs of foreign matter, aside from a few bits of black from the pump and sock.

Fuel pressure reads normal now, except it still bleeds down faster than I would like to see it. In a five minute time period after pressurizing the system, it dropped from about 42 lbs to 28 lbs. Much slower than before, but I'm not sure that this fast of a pressure is in the acceptable range. Maybe someone could clarify this?

So the misfire/bucking/rich condition still exists after all I have fixed and replaced. Although the distributor was replaced by the previous owner, I think it's time to swap it out with a new one along with new ICM/coil harness pigtails.

Any thoughts or advice is greatly appreciated!

[This message has been edited by ITALGT (edited 02-16-2015).]

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Report this Post02-16-2015 06:13 PM Click Here to See the Profile for LornesGTSend a Private Message to LornesGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by ITALGT:


The new Bosch fuel pump was installed a week ago. The one in the tank was the original Delco, and it obviously was due for replacement. Small bits of black rubber and/or plastic were starting to come out of the pump. The sock was completely black and clogged, and it was also collapsed onto the pump inlet. The pulsator was still there, and I replaced it with the submersible fuel hose. The tank itself looked really clean with no signs of foreign matter, aside from a few bits of black from the pump and sock.

Fuel pressure reads normal now, except it still bleeds down faster than I would like to see it. In a five minute time period after pressurizing the system, it dropped from about 42 lbs to 28 lbs. [i]Much[i] slower than before, but I'm not sure that this fast of a pressure is in the acceptable range. Maybe someone could clarify this?

Any thoughts or advice is greatly appreciated!


All that crap in the line could be in the new injectors keeping one or more open.
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Report this Post02-16-2015 07:14 PM Click Here to See the Profile for ITALGTSend a Private Message to ITALGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by LornesGT:


All that crap in the line could be in the new injectors keeping one or more open.


I thought of that too... although you would think the fuel filter would have prevented that from happening by capturing the debris before it got to the injectors.

I just installed the injectors a few weeks ago... I guess it would have been smarter to do the fuel pump first.


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