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'87 2.5 still having idle issues after 2 years of coping with it... by perceptionist
Started on: 10-08-2009 12:40 AM
Replies: 46
Last post by: perceptionist on 10-18-2009 02:44 PM
perceptionist
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Report this Post10-08-2009 12:40 AM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
My '87 2.5 fiero WILL NOT idle when cold unless I hold the gas pedal slightly. So while I'm getting ready for work, I wedge a board between the seat and the gas pedal till it warms up. After it is warm, it still idles crappy and rough intermittently but at least it won't die unattended and without aid. I live where it gets below freezing so it would be nice if I could install a remote starter, but considering the way it's behaving, that would be pretty much pointless.

I am completely lost on this. I posted a couple years ago about this listing all of the sensors etc I replaced on this thing following the purchase of a new (factory reman) engine. I can't find that thread which would help because it listed exactly all the things I bought. The list of things I have NOT yet bought is much shorter, so I will start there...

I have NOT yet replaced (which I understand might be capable of causing my issue):

the ECM
catalytic converter
fuel vapor canister.
TBI Fuel injector - although I have rotated between 6 different injectors all pulled from the car graveyard. I used the strobe (timing light) method to inspect the spray pattern so I could use the injector with the best pattern according to the instructions I read at the time (been a while so i can't remember my source, likely it was here on the forums)

From memory I HAVE replaced:

Engine
IAC
Fuel pressure regulator
Fuel pump & Screen
Fuel filter (was super clogged, but new filter changed nothing)
Ignition control module and coils
Plugs & Wires
Crank position sensor
Throttle position sensor
vacuum hoses
both temp sensors and there is a third (forget what it's called) on the intake... cold air sensor or something like that, located to the right of throttle body.
Added extra ground strap
new battery

I might be missing something on this list, when the suggestions start coming in, I will likely remember if I replaced it or not.

Years ago I bought WINALDL and all the wires etc... only to discover pretty much every Fiero is covered EXCEPT mine (1987 distributorless 2.5) Lucky me. So for this reason I am not sure how to confirm if my ECM is good to avoid unnecessary replacement.

I have a simple code reader. I haven't checked the codes being generated for like a year, but I remember it kept giving me a code 35 IAC and another one now and then. Before I finally bought the new IAC, I had 5 of them all pulled from junk yard, none of them changed anything, nor did the new one. I also replaced the IAC pigtail. It is late now so I will recheck the codes tomorrow and post them.

I am getting tired of keeping my foot on the gas & brake when I need to stop. After all this time and research, I would have hoped to solve this by now. I would hope to find a way to confirm any further replacements are necessary before doing them as I can't really afford to waste any more $$ on guessing on a solution.

Really looking for some advanced knowledge from the gurus out there rather than the usual typical troubleshooting which I think I have already covered.

Oh it has also been suggested that if the TBI has been adjusted at any time that it is almost impossible to get the picky ECM happy with any manual adjustments and that replacing the TBI will usually clear up the problem. Is there any way to know this for sure in my case before spending the money on a new one? The TBI appears to be in good shape, but through all my headaches I admit I have tinkered with it a bit as I felt I was out of ideas.

Thank you in advance for ANY help

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Report this Post10-08-2009 12:54 AM Click Here to See the Profile for KurtAKXSend a Private Message to KurtAKXDirect Link to This Post
If the IAC passage is plugged, you'll still get the IAC code no matter how many you put in the car. If I remember right, the code actually just says something about not being able to keep the idle within the target range.

If the throttle body has been tampered with, you can usually get it pretty close to a proper throttle blade setting by warming the engine up and plugging the IAC passage, and backing the idle screw out until the car will just barely idle, about 525 rpm or so.

On the early throttle bodies, plugging the passage temporarily is as easy as cramming a wad of masking tape in the IAC recess on top of the throttle body. It's been a couple of years since I've messed with a Model 700 TBI (87+ iron duke throttle body) so I don't remember what's involved.

Did you say your check engine light was on during this crappy running?
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TK
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Report this Post10-08-2009 12:59 AM Click Here to See the Profile for TKSend a Private Message to TKDirect Link to This Post
Have you confirmed your EGR is really closing and not hanging up? I see that a lot. If you can, pull it off and raise the diaphragm and release it quickly. It has to close and completely seal the passage. Do it 10 times to make sure. If not, replace it. You shouldn't be able to blow anything from the bottom up when it's closed.

Any EGR leakage will play havoc with idle especially cold idle.

Just a thought.
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perceptionist
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Report this Post10-08-2009 01:33 AM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
I haven't had the TB off since last summer, but when I did, I thoroughly cleaned it with carb cleaner and got a new gasket.

I will try resetting the idle screw as you described tomorrow.

Yes the engine light comes on when the idle drops then goes off shortly after the idle returns to normal.

I haven't checked the EGR lately, will do that tomorrow. I did get a brand new one last summer though when I discovered the diaphragm was shot.

I forgot to mention the exhaust also smells quite rich (not sure how to determine rich or lean ratio without winaldl), no smoke though.

Thanks for the replies, please keep em coming, I will try just about anything at this point.
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jetman
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Report this Post10-08-2009 07:01 AM Click Here to See the Profile for jetmanClick Here to visit jetman's HomePageSend a Private Message to jetmanDirect Link to This Post
 
quote
Originally posted by perceptionist:
Yes the engine light comes on when the idle drops then goes off shortly after the idle returns to normal.


Please pull the codes for us then reset the ECM computer by disconnecting the negative battery cable or weather pack connector.

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Report this Post10-08-2009 10:10 AM Click Here to See the Profile for mike-ohioClick Here to visit mike-ohio's HomePageSend a Private Message to mike-ohioDirect Link to This Post
Didn't see a replaced O2 sensor on your list of sensors replaced/tested.

IAC and EGR should both be checked.

Is it possible you have another vaccum leak? cruise control line , etc.?

When holding a constant 40 or 50mph does it run OK or surge?
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Report this Post10-08-2009 12:15 PM Click Here to See the Profile for Gravitic AnomalyClick Here to visit Gravitic Anomaly's HomePageSend a Private Message to Gravitic AnomalyDirect Link to This Post
The facts that the problem happens when the engine is cold and it smells rich leads me to think the problem is when the control is in open loop.
A heated O2 sensor might help. A new stock O2 sensor is always better than a 20+ year old sensor.
Sometimes when you can not figure out what the problem is it can help to find out what it isn't. For example systematically disconnect sub-systems. Pull the brake booster vacuum line and plug the port. Run the engine. Did the problem change or stay the same. Reconnect the booster. Pull the Evap line to the engine and plug the port. Try again. Go right on down the line with anything you can think of.
Borrow a Memcal from someone swap it with your one. The analog portion of the Memcal can drift with age and temperature.

- Tim
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Report this Post10-08-2009 12:35 PM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
I wound up driving my truck today but will get those codes by this evening.

IAC and EGR are both new, but I will recheck.

No cruise on this car, I have checked all the other vacuum lines but it has been a year since, so I will check them again, although this problem has been going on for much longer than that.

When driving at speed, the only thing I notice is that it seems to run slightly rough, but barely noticeable. The issue is most apparant at idle and take off all the time, but especially when cold.

I think I will go ahead and purchase a new O2 sensor, been putting it off due to budget.

I'm unfamiliar with the term "Memcal". What is this?

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Report this Post10-08-2009 12:50 PM Click Here to See the Profile for Gravitic AnomalyClick Here to visit Gravitic Anomaly's HomePageSend a Private Message to Gravitic AnomalyDirect Link to This Post
The Memcal is a plug in module in the engine computer (ECM). It has two parts in it. The first part is the Memory. Basically it contains the computers program. The second part is the Analog Calibration. This is a hardware backup to operate the engine when in open loop mode or "limp home" mode. You access it by removing the two screws on the face of the ECM and remove a cover.
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Report this Post10-08-2009 01:27 PM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
 
quote
Originally posted by Gravitic Anomaly:

The Memcal is a plug in module in the engine computer (ECM). It has two parts in it. The first part is the Memory. Basically it contains the computers program. The second part is the Analog Calibration. This is a hardware backup to operate the engine when in open loop mode or "limp home" mode. You access it by removing the two screws on the face of the ECM and remove a cover.


Ok, so there is a potential that if the issue is in the ECM, I may not need to replace the entire ECM, only the Memcal? Are these items available new or will I still need to replace entire ECM if this is the problem?

It sounds like the "Memcal" is the same thing as the EEPROM chip, is this correct?

[This message has been edited by perceptionist (edited 10-08-2009).]

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Report this Post10-08-2009 01:38 PM Click Here to See the Profile for mike-ohioClick Here to visit mike-ohio's HomePageSend a Private Message to mike-ohioDirect Link to This Post
I had a brand new plug wire that was separated inside and caused similar issues.

However it would idle fine just rough on accelaeration.

I pulled the plugs and noticed number 3 was a different color than all the others (black and a little fouled).

Replaced that plug wire and and it corrected the problem.

Wouldn't hurt to take a look at the plugs. It's pretty easy to do on a 87 duke. At least might give an indiacation of how rich or lean it is running.
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Report this Post10-08-2009 01:46 PM Click Here to See the Profile for 2.5Send a Private Message to 2.5Direct Link to This Post
Yeah go for the 02 sensor, $19 at Autozone.
I would think rich exhaust could be an effect of bad 02 sensor.

[This message has been edited by 2.5 (edited 10-08-2009).]

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Report this Post10-08-2009 03:40 PM Click Here to See the Profile for TKSend a Private Message to TKDirect Link to This Post
 
quote
Originally posted by perceptionist:


I haven't checked the EGR lately, will do that tomorrow. I did get a brand new one last summer though when I discovered the diaphragm was shot.

I forgot to mention the exhaust also smells quite rich (not sure how to determine rich or lean ratio without winaldl), no smoke though.

Thanks for the replies, please keep em coming, I will try just about anything at this point.


If it's been really rich it might have carboned up the EGR so it doesn't close completely.

Keep us posted!
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Report this Post10-08-2009 05:35 PM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
 
quote
Originally posted by TK:


If it's been really rich it might have carboned up the EGR so it doesn't close completely.

Keep us posted!


Sounds more and more like the O2 sensor replacement would be a good first step.

They must have recently come way down in price,

If I remember correctly I priced these at around $89 more than a year ago, which is why I did not replace it yet.
BTW, one of the sensors I replaced which I referred to earlier as the "Cold air sensor" is the MAT sensor.

[This message has been edited by perceptionist (edited 10-08-2009).]

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Report this Post10-08-2009 05:50 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickDirect Link to This Post
 
quote
Originally posted by perceptionist:

Sounds more and more like the O2 sensor replacement would be a good first step.

They must have recently come way down in price,

If I remember correctly I priced these at around $89 more than a year ago



The brand of the O2 sensor makes a big difference in price, as does where you buy it from. I was able to snag three brand new Delco O2 sensors for $9.99 apiece on eBay.

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Report this Post10-08-2009 05:55 PM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
 
quote
Originally posted by Patrick:


The brand of the O2 sensor makes a big difference in price, as does where you buy it from. I was able to snag three brand new Delco O2 sensors for $9.99 apiece on eBay.


Ah that's another thing...

I already learned my lesson with regard to buying any sensors NOT made by AC Delco for my Fiero. I have seen the warnings here on the boards and chose to ignore them when I bought a sensor in the past that did not function properly... my memory is shot, I can't remember the sensor but I definitely remember the difference between the off brand and the AC Delco.
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Report this Post10-08-2009 06:03 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickDirect Link to This Post

First choice would be Delco O2 sensors. I've also heard that Denso O2 sensors work fine. However, I've read lots of bad things about Bosch O2 sensors in Fieros.
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Report this Post10-08-2009 06:20 PM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
 
quote
Originally posted by KurtAKX:

If the throttle body has been tampered with, you can usually get it pretty close to a proper throttle blade setting by warming the engine up and plugging the IAC passage, and backing the idle screw out until the car will just barely idle, about 525 rpm or so.


I am going to try this, but I have been reading all day today here at work (yeah I'm really busy) about fiero issues here and on other various sites... I found the following and wanted to run it by you guys to see if there is a definitive way to check this since I have seen slightly different methods:

Taken from: http://myfiero.oceanmoon.com/?p=515

"The Haynes EFI book says set the idle according to the VECI label, but of course the VECI label doesn’t say anything. Near as I can tell… If you set the Idle Stop for about 800-850 RPM then the IAC should be able to do its job properly.
Once you are done, shut off the car, plug the IAC in, and clear any errors that may have been set in the ECM."

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Report this Post10-08-2009 06:28 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreDirect Link to This Post
See cave. Read My Page Here... Powertrain, Engine, 4 cyl, 700 tbi

Check MAT... One sensor he didn't replace.
See cave, DIS ignition and 700 tbi.
Check Vacuum leak.
Check TBI mounting bolts. 2 long main mounting (air cleaner is on it) and 2 short connect 2 half of tbi.
Check exhaust leak.
Auto tranny? See cave torque strut.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)


The Ogre's Fiero Cave (It's also at the top of every forum page...)

[This message has been edited by theogre (edited 10-08-2009).]

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KurtAKX
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Report this Post10-08-2009 06:29 PM Click Here to See the Profile for KurtAKXSend a Private Message to KurtAKXDirect Link to This Post
The problem with setting your idle to the VECI label with the IAC still hooked up is that for all you know, the IAC may be nearly all the way open at the time you're setting the idle, and then there won't be enough valve travel left to allow for cold-start.

The base idle throttle plate position needs to be determined without the effect of IAC airflow.
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Report this Post10-08-2009 06:59 PM Click Here to See the Profile for jetmanClick Here to visit jetman's HomePageSend a Private Message to jetmanDirect Link to This Post
 
quote
Originally posted by Patrick:


First choice would be Delco O2 sensors. I've also heard that Denso O2 sensors work fine. However, I've read lots of bad things about Bosch O2 sensors in Fieros.


I was under the impression that Denso makes the O2 sensors for AC Delco, 234-1001 is the Denso part number, works great in my Fiero, definitely stay away from Bosch in the Fiero, just don't perform or durable.


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Report this Post10-08-2009 07:15 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickDirect Link to This Post
 
quote
Originally posted by jetman:

I was under the impression that Denso makes the O2 sensors for AC Delco, 234-1001 is the Denso part number, works great in my Fiero...



I guess that's why the Denso O2 sensors work well in the Fiero then.

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Report this Post10-08-2009 10:54 PM Click Here to See the Profile for goldironSend a Private Message to goldironDirect Link to This Post
If EGR valve is clean and appears to seal, you can unplug the vacuum line. I've not noticed any change in performance with EGR opening or not. As others have suggested, plugs wires could be causing the problem. The last new set I bought had a bad wire.

When everything else has been tried, do this: There is a ground circuit called 453 that runs from the ignition control module straight to the ECM. Didn't know which connector at the ECM had the ground circuit so I loosened and reset both. Idle has improved and occasional stalling when trying to depart from a stop sign has gone. Leaned about this ground circuit as a potential problem from the shop manual.
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Report this Post10-08-2009 11:07 PM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
My MAT sensor was replaced last summer, In my first post I was unsure of what it was called so I referred to it as the "cold air sensor" from poor memory

I have been outside working on it for the past couple hours.

EGR is good

I will soon order a new filter that goes under the fuel vapor canister, but cleaned the one I have for now.

The code I am getting is the IAC code #35 which is what I have always gotten.

I currently have the IAC off, and am trying to find the exact info on specifically what needs to be plugged to re set my idle stop screw... I forget if plugging the large outside hole is all that is needed, or if I need to specifically plug one of the smaller holes inside there.... if I plugging the outside hole is all I need to do, I have a ball from a mouse that fits over that hole nice & tight..... I will be back periodically to check replies, but for now I am outside fooling with it...

Think I will head to the parts store to see about an AC Delco O2 sensor....

Oh also with the air cleaner assembly off, I am noticing a hi pitch whistle similar to a vacuum leak, but I found it to be coming from between the throttle plate (butterfly) and the inside wall of the TB, only at idle... goes away when I move the throttle...
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Report this Post10-09-2009 12:19 AM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
Ok, I think I have got the idle stop screw set correctly... well at least closer to being correct. Then I pulled the ECM fuse to reset codes etc... then went through the driving procedure (through town, then over 45, then stop turn off, turn on and drive some more etc..) to allow the ECM to relearn the IAC and other sensor inputs.

It seems to be running smoother now. It is idling pretty low at around 500, but I understand the process for the ECM to get fully acclimated in its re learning everything is gradual and improvement should become apparent over time (how much time?)

Oh also since I cleared the codes, I decided to recheck fault codes after my test drive.... I am still getting the #35 IAC, and now I'm seeing a code #44 O2 sensor and/or lean fuel mixture detected.

This actually sounds promising as I think I am finally getting closer to solving this thing. The 2 parts stores near my house only stock Bosch O2 sensors.

I will be online and making calls to find a local supplier for an AC Delco sensor tomorrow... if not, I plan to order one from the fiero store.
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Report this Post10-09-2009 12:26 AM Click Here to See the Profile for White 84 SESend a Private Message to White 84 SEDirect Link to This Post
I would concentrate my attention on the IAC, it's wires, and it's passage ways if I were you. Your IAC seems to be choking your engine. You do have the correct IAC in? If it's dirty or too big it wont let in air and it will stall at idle.
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Report this Post10-09-2009 12:35 AM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
 
quote
Originally posted by White 84 SE:

I would concentrate my attention on the IAC, it's wires, and it's passage ways if I were you. Your IAC seems to be choking your engine. You do have the correct IAC in? If it's dirty or too big it wont let in air and it will stall at idle.


The IAC and the pigtail to it are both brand new from the fiero store. The TBI was fully disassembled last summer, still looks clean.

From what I have been reading, the ECM is SUPER picky about the idle stop screw being EXACTLY where it is supposed to be. Now that I possibly got that correct, the new O2 sensor code has me wanting to replace that since I have never replaced it since I've owned this car (about 4 years) Not sure how long the same sensor was in before that.

I just read that it should be changed out every 2 years so before I look at anything else, I should probably replace it, clear the codes and see where I stand after that.
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Report this Post10-09-2009 02:23 AM Click Here to See the Profile for jetmanClick Here to visit jetman's HomePageSend a Private Message to jetmanDirect Link to This Post
 
quote
Originally posted by perceptionist:

From what I have been reading, the ECM is SUPER picky about the idle stop screw being EXACTLY where it is supposed to be. Now that I possibly got that correct,,,,,,,,,,,,,


Here is an excellent post on resetting the idle set screw.

https://www.fiero.nl/forum/A...06-2-060970.html#p12

EDIT, I posted the link since you already made some adjustments to the idle stop screw. I would never advocate trying to do this to *fix* an idle issue unless every other possible item has been checked and i would recommend an *auto-scanner* of some type to get the counts just right. Fair warning given.

[This message has been edited by jetman (edited 10-09-2009).]

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Report this Post10-09-2009 01:43 PM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
 
quote
Originally posted by jetman:


Here is an excellent post on resetting the idle set screw.

https://www.fiero.nl/forum/A...06-2-060970.html#p12

EDIT, I posted the link since you already made some adjustments to the idle stop screw. I would never advocate trying to do this to *fix* an idle issue unless every other possible item has been checked and i would recommend an *auto-scanner* of some type to get the counts just right. Fair warning given.



Hey that's the same write up I used. I printed it out a long time ago and just found it again crumpled up in my trunk last night.

Yeah through all of my trouble shooting over the past couple years since the new motor went in, I did just about everything to remedy this idle issue before I finally removed the seal and manually adjusted the idle stop screw. At that time I had not yet learned how bad that was.

It would be nice to have a compatible scan tool, but as I understand it, this is not possible with the 87-88 distributorless ignition systems. I have WinALDL and a cable but it is not compatible with my ECM.

I just wrote to the fiero store asking about this and this was the reply:

"GM's computer software is completely different on the 87/88's because of the distributorless ignition system. The only scan tools that I know of would be the expensive type scanners that garages/dealers use (made by Snap-on, Matco, OTC, etc.)."

I only found one place in my area that has the AC Delco O2 sensor for $54.12 after tax, the guy said the "at cost" price for these is around $25. He did not seem too sure which sensor was correct for my car. He suspected it was part #213502 which he says is discontinued but that there is a universal one (part #213500) that should work.

I am not very comforted by words like "should work".

Does anyone know the definitive AC Delco part # for the CORRECT o2 sensor for a 1987 Fiero with 2.5L, manual trans, VIN "R"

My online search is proving to be rather confusing on this.

The listing for the one the fiero store sells does not indicate what brand it is but it sells for $19.95 so I am not sure if it is AC Delco. I sent an email to find out.

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Report this Post10-09-2009 01:58 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreDirect Link to This Post
 
quote
Originally posted by KurtAKX:

The problem with setting your idle to the VECI label with the IAC still hooked up is that for all you know, the IAC may be nearly all the way open at the time you're setting the idle, and then there won't be enough valve travel left to allow for cold-start.

The base idle throttle plate position needs to be determined without the effect of IAC airflow.


Again see cave... 700 tbi - Idle stop
If he did it, the IAC is closed.
If he check with scan tool... reconnect IAC and reset again... (700 tbi, IAC reset) around 15 IAC step. Engine on. (Auto tranny not in gear. Auto in drive should be around 40-45 step.) I think in bin a long while. I don't have any note about it.

Originally posted by perceptionist:
It would be nice to have a compatible scan tool, but as I understand it, this is not possible with the 87-88 distributorless ignition systems. I have WinALDL and a cable but it is not compatible with my ECM.

--> Yes. 87-88 Use 1227748 P4 ECM. See cave, 4 cyl. quick ref, dis ignition, etc

I just wrote to the fiero store asking about this and this was the reply:

"GM's computer software is completely different on the 87/88's because of the distributorless ignition system. The only scan tools that I know of would be the expensive type scanners that garages/dealers use (made by Snap-on, Matco, OTC, etc.)."

-->Half right. 1227748 is different ECM family. P4 is more upgrade. Will not work with WinALDL or TFS/Oliver C3 ECM scan tool. 1227748 P4 ECM give you cruise control build in, fast data rate, and other function.
AutoXray is good for C4, P4, and other ODB1 GM.

I only found one place in my area that has the AC Delco O2 sensor for $54.12 after tax, the guy said the "at cost" price for these is around $25. He did not seem too sure which sensor was correct for my car. He suspected it was part #213502 which he says is discontinued but that there is a universal one (part #213500) that should work.

I am not very comforted by words like "should work".

Does anyone know the definitive AC Delco part # for the CORRECT o2 sensor for a 1987 Fiero with 2.5L, manual trans, VIN "R"

--> O2 sensor use same as any L4, Vin R. Use bosch or ac delco, be fine.
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[This message has been edited by theogre (edited 10-09-2009).]

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perceptionist
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Report this Post10-09-2009 02:59 PM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
Just to be clear in my understanding, when the IAC is "Closed" the pintle is extended plugging the hole and when it's "open" the pintle is retracted allowing air to flow, correct?

I just read the info at the cave and will try that later this afternoon. I pretty much did that same procedure last night only instead of setting the idle to around 800-850, the directions I was following said to set it as low as it could possibly idle.

I have seen other instructions stating that during the same procedure the idle should be set to 125 rpm below the ideal idle speed of 900, so 900 minus 125 = 775. I have not tried that one yet nor have I tried the 800-850 as stated in the cave. I will include both in my search for a solution.

Regarding the correct o2 sensor, I went to the AC Delco site and did a parts search for my car and got the following results..



3 different part #s for the same part on the same car, unless I am misunderstanding the results
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Report this Post10-09-2009 05:47 PM Click Here to See the Profile for johnt671Send a Private Message to johnt671Direct Link to This Post
I would forget the first one as that is the universal fit type that you need to crimp the wire to the connector. The other two supply a new connector. I don't know what the difference is between the other two.
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Report this Post10-13-2009 01:10 PM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
Ok so for the first throttle stop adjust procedure, I set the throttle for the lowest possible idle before reconnecting IAC then gave the ECM a few days of driving to re learn after which I checked and found code #35 (IAC) and #44 (O2 sensor/lean condition). The car ran smoother but idle mostly stayed around 500-600rpm and occasionally bumped up to 900 for short intervals (which is where it should be all the time.)

A couple days ago, I did this procedure again following the info from the cave and setting the throttle stop to achieve an rpm of 800-850. The car idles noticeably rougher now. The idle speed behaves as stated above only its 500-600 half the time and 900 the other half. It's also a bit harder to keep running when cold and smells richer. Checked codes this morning when I got to work. Still getting #35 (IAC) and #44 (O2 sensor/lean condition) I did clear the codes prior to each change of settings.

Next I plan to try the 3rd procedure I read stating to set the throttle stop to 125 rpm below the desired rpm (900) and see what that gets me.

I have never been able to get this car to start without applying some throttle and keeping the throttle depressed until it is warm. On the other hand, my old 1983 toyota pickup that looks like it rolled end over end down into a canyon, starts right up and idles fine in any temp as does my 1988 Fiero GT.... its just this '87 that is such a big mystery.

BTW, I got a reply from the Fiero store regarding the brand of O2 sensor they sell.
It's made by "Standard Ignition" Does anyone know how this compares to AC Delco (better worse, crap)?

Thanks

[This message has been edited by perceptionist (edited 10-13-2009).]

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Report this Post10-14-2009 10:35 PM Click Here to See the Profile for HudiniSend a Private Message to HudiniDirect Link to This Post
The one time I had to crack the throttle before the car would start it was a bad wire at the IAC connector. I found it when I removed the IAC and put the car in diagnostic mode. (Keep your finger over the pintle or it will shoot into outer space) Now when I turned the key to ON the IAC should have vibrated as the pintle is driven fully out (closed). On mine the vibration was intermittent as I moved the IAC in my hand. About that time one of the 4 wires came loose and I found my problem.

Earlier you wrote you replaced the IAC connector along with the IAC. How sure are you that the wires are correct and secure? The wires must be on the correct pins for the stepper motor to work.
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Report this Post10-14-2009 11:14 PM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
"(Keep your finger over the pintle or it will shoot into outer space)"

This is good to know in case I need a weapon if I am ever carjacked,

"Earlier you wrote you replaced the IAC connector along with the IAC. How sure are you that the wires are correct and secure? The wires must be on the correct pins for the stepper motor to work."

Well, I did buy a new pigtail and replaced each wire one at a time to ensure they were correct. As I am typing this, I wondered if the previous wire positions were wrong, but there was a time when I bought the car when it started and ran fine. Actually it was still running fine when I decided to put a fresh engine in it.

My reasoning was that it was my only vehicle and I had just moved up to Washington and didn't know anyone. It had high miles so I just wanted security of piece of mind since I knew I would be keeping it. Ever since the new motor went in, I never got it quite right even after all the troubleshooting.

When I do the procedure described above putting the car in diag mode and turning on key, I can feel the IAC vibrating non stop, I wait like 30 seconds then disconnect IAC, take out of diag, then start and adjust screw. I will try this with IAC removed to see if it is actually doing it's job.

I remember my old IAC pintle popping out a couple years back when it was off the TB which is mainly why I replaced it since I read somewhere that if you allow it to come all the way out, the IAC should be replaced, is this true? It would be good to know in case it happens again.

I did manage to get the pintle back in the old one to where it "appeared" to function properly, but I'm no expert.

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Report this Post10-14-2009 11:26 PM Click Here to See the Profile for HudiniSend a Private Message to HudiniDirect Link to This Post
If you found and replaced the pintle it will be fine. I was lucky too and found mine after a bit of searching. The main thing is pressing in on the pintle to seat it a bit so it does not bottom out when you reinstall it. You can bend the shaft if it's out too far although the '87 has the newer style IAC with 2 screws holding it so bending the shaft is not likely.

Another test needs a helper. Remove the IAC, reconnect the connector, hold it in one hand with your finger over the pintle. Use the other hand to place a finger over the IAC hole in the throttle body. Now have your helper start the car. Use your finger over the IAC hole to control idle air flow. You should feel the IAC pintle working back and forth in response to the idle changes as it tries to control idle air. Make sure your helper can quickly turn the car off if the idle gets too high.

[This message has been edited by Hudini (edited 10-14-2009).]

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Report this Post10-14-2009 11:56 PM Click Here to See the Profile for perceptionistSend a Private Message to perceptionistDirect Link to This Post
 
quote
Originally posted by Hudini:

Another test needs a helper. Remove the IAC, reconnect the connector, hold it in one hand with your finger over the pintle. Use the other hand to place a finger over the IAC hole in the throttle body. Now have your helper start the car. Use your finger over the IAC hole to control idle air flow. You should feel the IAC pintle working back and forth in response to the idle changes as it tries to control idle air. Make sure your helper can quickly turn the car off if the idle gets too high.



Ok now here is where I always get confused because no one has yet specifically explained which hole they mean when referring to "the IAC hole".

When the IAC is off the TB, there is the largest hole in the side of the TB that the IAC covers when installed, then there is the smaller hole in the back which get covered by the tip of the pintle when it's extended.

Then there is another hole inside the (first mentioned) large hole along the bottom, and yet another if I remember correctly to the right as you are looking in the large hole. (I will try to get a picture)

Now for the finger over the hole test, will covering the largest hole alone work, or does it need to be just the small pintle tip hole ONLY, or a combination of any of these....?

Sorry to over think this, but I think it would make a difference since air flow between two or more of these holes should matter right?

[This message has been edited by perceptionist (edited 10-14-2009).]

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Report this Post10-15-2009 12:18 AM Click Here to See the Profile for PatrickSend a Private Message to PatrickDirect Link to This Post
 
quote
Originally posted by perceptionist:

Now for the finger over the hole test...



With the IAC valve in place, (while the car is running) put your finger over the hole which is apparent when the rubber air filter snorkel has been removed. It'll try to suck your fingertip into the hole. Don't let it. The engine should stall.
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Report this Post10-15-2009 08:04 AM Click Here to See the Profile for HudiniSend a Private Message to HudiniDirect Link to This Post
I'm talking the hole where the pintle would normally seat. I don't have my 700 TBI in front of me to see how easy it would be to stick your finger in there, especially on the car so use your best judgment if it's safe. Your finger is taking the place of the pintle moving in and out. The other holes don't matter for this short test.
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Report this Post10-15-2009 03:00 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickDirect Link to This Post
Just realized you were talking about the duke. I was referring to the V6. Oh well, probably the same procedure.

 
quote
Originally posted by Patrick:

With the IAC valve in place, (while the car is running) put your finger over the hole which is apparent when the rubber air filter snorkel has been removed. It'll try to suck your fingertip into the hole. Don't let it. The engine should stall.

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