Pennock's Fiero Forum
  Technical Discussion & Questions
  Rebuilt Delco Distributor installed, but...

Post New Topic  Post A Reply
Email This Page to Someone! | Printable Version


next newest topic | next oldest topic
Rebuilt Delco Distributor installed, but... by Rich Truett
Started on: 05-14-2015 09:46 PM
Replies: 23 (360 views)
Last post by: phonedawgz on 05-18-2015 03:23 AM
Rich Truett
Member
Posts: 71
From: Detroit, Michigan USA
Registered: Mar 2015


Feedback score: N/A
Leave feedback

Rate this member

Report this Post05-14-2015 09:46 PM Click Here to See the Profile for Rich TruettClick Here to Email Rich TruettSend a Private Message to Rich TruettEdit/Delete MessageReply w/QuoteDirect Link to This Post
...My 1988 Formula STILL has hot idling issues.

First, off, though, the car runs far, far better with the rebuilt distributor. The smoothness at idle in gear that was never there now is.
The car also is far faster than it has ever been.
And I don't even have the timing set properly -- I just earballed and got it close. I will time it this weekend.

So, after 15 minutes of driving and the engine up to working temperature the idling starts wandering and the ICM changes the timing to compensate, same as before, but not quite enough to make it stall.

So, nothing really has changed with the idle situation.

Again: no trouble codes.

I have not checked the fuel pressure, but I can't see how that would make the ICM adjust the idle, and the ICM can change the fuel pressure.

The last thing I am going to try before I get rid of the car is a new ECM. They are cheap enough.

I feel like I am almost there...

Rich Truett

IP: Logged
PFF
System Bot
Gall757
Member
Posts: 10622
From: Holland, MI
Registered: Jun 2010


Feedback score: N/A
Leave feedback





Total ratings: 88
Rate this member

Report this Post05-14-2015 10:04 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
The ICM can't adjust spark or fuel delivery by itself....it send signals to the ECM and the software does it......so both are involved.

Is your heat problem fixed?
IP: Logged
fierogt28
Member
Posts: 2751
From: New-Brunswick, Canada.
Registered: Feb 2005


Feedback score:    (14)
Leave feedback

Rate this member

Report this Post05-14-2015 11:54 PM Click Here to See the Profile for fierogt28Click Here to Email fierogt28Send a Private Message to fierogt28Edit/Delete MessageReply w/QuoteDirect Link to This Post
Good news, nice to hear.

I think it would be a good idea to time the engine before any comments. The factory spec is 10* advance.
You need a timing light, no question.

Don't give up...

------------------
fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. Beechwood interior, All original.

IP: Logged
Rich Truett
Member
Posts: 71
From: Detroit, Michigan USA
Registered: Mar 2015


Feedback score: N/A
Leave feedback

Rate this member

Report this Post05-15-2015 02:33 PM Click Here to See the Profile for Rich TruettClick Here to Email Rich TruettSend a Private Message to Rich TruettEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yes, I will time the car this weekend. I have a timing light, just marking the pulley and timing indicator in such tight confines is my only concern.

The car really is running well. Except for this one issue, it's good.

RT
IP: Logged
85 SE VIN 9
Member
Posts: 690
From: Harwood Heights, IL, USA
Registered: Apr 2010


Feedback score: N/A
Leave feedback

Rate this member

Report this Post05-15-2015 02:41 PM Click Here to See the Profile for 85 SE VIN 9Click Here to Email 85 SE VIN 9Send a Private Message to 85 SE VIN 9Edit/Delete MessageReply w/QuoteDirect Link to This Post
You probably don't need to mark the timing mark. You'll probably be able to see it.

Sounds like a vacuum leak. Lots of possibilities there.
IP: Logged
fierofool
Member
Posts: 11747
From: Auburn, Georgia USA
Registered: Jan 2002


Feedback score:    (13)
Leave feedback





Total ratings: 150
Rate this member

Report this Post05-15-2015 03:19 PM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
It might be easier to mark the balancer from underneath the car. But you'll still need to reach down to the degree indictor to mark it.
IP: Logged
css9450
Member
Posts: 4987
From: Glen Ellyn, Illinois, USA
Registered: Nov 2002


Feedback score: (2)
Leave feedback





Total ratings: 82
Rate this member

Report this Post05-15-2015 04:06 PM Click Here to See the Profile for css9450Click Here to Email css9450Send a Private Message to css9450Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fierofool:

It might be easier to mark the balancer from underneath the car.


Absolutely. The balancer has three marks, each 120 degrees apart. By raising the car and looking underneath, its much easier to tell which one is which (you want to mark the WIDE one), as opposed to peering down from above where you have just a tiny, narrow little view.

IP: Logged
Rich Truett
Member
Posts: 71
From: Detroit, Michigan USA
Registered: Mar 2015


Feedback score: N/A
Leave feedback

Rate this member

Report this Post05-15-2015 10:02 PM Click Here to See the Profile for Rich TruettClick Here to Email Rich TruettSend a Private Message to Rich TruettEdit/Delete MessageReply w/QuoteDirect Link to This Post
I marked the proper section of the pulley tonight on the pulley and set the timing.

I followed instructions and connected the terminals on the ADL

While shining the timing light on the pointer, I noticed the timing mark was not steady, that is it was jumping around. Hmmm. I've not seen that before.

Anyway, I set the timing on 10 degrees.

Holy cow is that car running well now fast and very smooth on acceleration.

But the same old problem still there. It runs like **** when hot and idling. Rough, feels like the engine is missing.

This car will not idle smoothly when it gets hot.

Something is causing the ECM to adjust the timing to compensate for whatever is going on.

Could it be a fuel pressure issue?

IP: Logged
fierogt28
Member
Posts: 2751
From: New-Brunswick, Canada.
Registered: Feb 2005


Feedback score:    (14)
Leave feedback

Rate this member

Report this Post05-15-2015 11:30 PM Click Here to See the Profile for fierogt28Click Here to Email fierogt28Send a Private Message to fierogt28Edit/Delete MessageReply w/QuoteDirect Link to This Post
Rich, by how much RPMs is the idle fluctuating from 900RPM?

What shape is the harmonic balancer on this fiero? Make sure the rubber insulation is not cracked
or dry rotted away. The balancer can't be loose or rotate clockwise and counter-clockwise. (back n forth)

Fuel pressure spec on the fiero 2.8L is between 40.5 to 47psi. You can check this by access to the
Schrader valve with a gauge on the fuel rail next to the thermostat housing. I have a fuel gauge mounted
on my fuel rail, and honestly I like the idea of having it. I can monitor the pressure when the deck-lid
is open / engine running, and see the pressure when the engine is stopped.
IP: Logged
fierogt28
Member
Posts: 2751
From: New-Brunswick, Canada.
Registered: Feb 2005


Feedback score:    (14)
Leave feedback

Rate this member

Report this Post05-15-2015 11:40 PM Click Here to See the Profile for fierogt28Click Here to Email fierogt28Send a Private Message to fierogt28Edit/Delete MessageReply w/QuoteDirect Link to This Post
BTW, the ICM has nothing to do with the fuel pressure. The fuel pump builds the pressure and the fuel pressure regulator
controls the fuel psi to the factory specs.

The ICM is an electrical module for ignition control.

------------------
fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. Beechwood interior, All original.

IP: Logged
Rich Truett
Member
Posts: 71
From: Detroit, Michigan USA
Registered: Mar 2015


Feedback score: N/A
Leave feedback

Rate this member

Report this Post05-16-2015 12:33 AM Click Here to See the Profile for Rich TruettClick Here to Email Rich TruettSend a Private Message to Rich TruettEdit/Delete MessageReply w/QuoteDirect Link to This Post
The harmonic balancer looked fine tonight. I see nothing abnormal there.

The idle goes like this:

Smoothly at first 850 900 RPM in gear, foot on brake.

When the engine is hot...

The idle starts to wander, down a bit, then up to 1,000-1,100, then it starts slowly sinking, when it gets to 750, it jumps back to around 1400 and then starts down again. I have a small exhaust leak and I can hear the tone of the engine change to very labored running, as if the timing was too far advanced or retarded. Then the idle gets slightly rough as the engine gets hotter. Then idle sinks into the 600 to 700 range. The lower it sinks the more the timing changes to bring the idle back up.

I am convinced the timing is jumping around when the engine is hot. When the engine is at normal temp I can see the tacho needle getting jumpy. It seems an electrical issue related to the ignition.

But if the fuel pressure is dropping slightly when the car is hot, would that cause the ECM to make the engine run faster by adjusting the spark timing?

Rich

[This message has been edited by Rich Truett (edited 05-16-2015).]

IP: Logged
PFF
System Bot
Patrick
Member
Posts: 30131
From: Vancouver, British Columbia, Canada
Registered: Apr 99


Feedback score: (1)
Leave feedback





Total ratings: 442
Rate this member

Report this Post05-16-2015 01:09 AM 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 Rich Truett:

I am convinced the timing is jumping around when the engine is hot.


I suppose a simple test for that is to jump the A B terminals in the ALDL port to lock in the base timing when the engine is good and hot... and see what the idle does.

[This message has been edited by Patrick (edited 05-16-2015).]

IP: Logged
Csjag
Member
Posts: 3170
From: Ocklawaha,Fl, USA
Registered: Dec 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post05-16-2015 12:48 PM Click Here to See the Profile for CsjagClick Here to Email CsjagSend a Private Message to CsjagEdit/Delete MessageReply w/QuoteDirect Link to This Post
How many miles on the engine? Is it possible that there is too much slack in the timing chain and when the oil heats up it causes the timing to jump around?
IP: Logged
Rich Truett
Member
Posts: 71
From: Detroit, Michigan USA
Registered: Mar 2015


Feedback score: N/A
Leave feedback

Rate this member

Report this Post05-16-2015 03:13 PM Click Here to See the Profile for Rich TruettClick Here to Email Rich TruettSend a Private Message to Rich TruettEdit/Delete MessageReply w/QuoteDirect Link to This Post
the car and engine have 55,000.

Next new part to go in is a rebuilt AC Delco ECM.

Rich
IP: Logged
phonedawgz
Member
Posts: 17009
From: Green Bay, WI USA
Registered: Dec 2009


Feedback score:    (23)
Leave feedback





Total ratings: 290
Rate this member

Report this Post05-16-2015 03:48 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
When scanning the engine when it is hot, does the scan show the ECM is receiving the correct temperature data, or does the ECM receive a temperature that is way off cold or hot?

Does the MAT/IAT temperature look correct?

No OBD1 scanner - http://reddevilriver.com/aldl.html

It's unlikely to be a bad ECM. Could be but unlikely.

You can also then look to see what the ECM is commanding as far as spark advance when this happens.

Try this also - Engine hot idling at the correct speed - Unplug the IAC. Does that 'freeze' the idle speed? If so your idle speed variations are not coming from timing changes/

[This message has been edited by phonedawgz (edited 05-16-2015).]

IP: Logged
Rich Truett
Member
Posts: 71
From: Detroit, Michigan USA
Registered: Mar 2015


Feedback score: N/A
Leave feedback

Rate this member

Report this Post05-16-2015 04:58 PM Click Here to See the Profile for Rich TruettClick Here to Email Rich TruettSend a Private Message to Rich TruettEdit/Delete MessageReply w/QuoteDirect Link to This Post
The rebuilt AC/Delco ECM was only $69 on fleabay. So, it can't hurt.

I have tried unplugging the IAC; it makes no difference. I'm convinced it is the timing jumping around.

I don't have a scanner.

R
IP: Logged
Csjag
Member
Posts: 3170
From: Ocklawaha,Fl, USA
Registered: Dec 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post05-16-2015 08:12 PM Click Here to See the Profile for CsjagClick Here to Email CsjagSend a Private Message to CsjagEdit/Delete MessageReply w/QuoteDirect Link to This Post
I apologize if I missed this, but have you cleaned the existing grounds and added ground straps?
IP: Logged
Rich Truett
Member
Posts: 71
From: Detroit, Michigan USA
Registered: Mar 2015


Feedback score: N/A
Leave feedback

Rate this member

Report this Post05-16-2015 10:41 PM Click Here to See the Profile for Rich TruettClick Here to Email Rich TruettSend a Private Message to Rich TruettEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have not cleaned the existing grounds, but I have tried adding an additional ground from the battery directly to the engine.
Makes no difference.

Tinkered with it tonight.
I reinstalled the factory EGR valve.

That has helped a bit.
She's really running well except at hot idle. Now it won't stall, but the speed drops and it runs roughly, almost like it is missing.

When It was at this point, I tried:
Disconnecting the IAC -- no changes
Unplugging the MAP -- no changes
Connecting the ALDL -- no initial change, but then when I undid the ALDL, the RPMs increased from around 800 to 1300 and the engine smoothed out; in a few seconds it settled into a nice, smooth idle at 950. But it couldn't hold that, and then eventually started idling roughly again.

There is one code: 44. But I do have a small exhaust leak.

Rich
IP: Logged
fierogt28
Member
Posts: 2751
From: New-Brunswick, Canada.
Registered: Feb 2005


Feedback score:    (14)
Leave feedback

Rate this member

Report this Post05-16-2015 11:32 PM Click Here to See the Profile for fierogt28Click Here to Email fierogt28Send a Private Message to fierogt28Edit/Delete MessageReply w/QuoteDirect Link to This Post
Rich, if you have code 44 set, check the following...

The ECM will set code 44 when the ECM detects a low voltage from the oxygen sensor and the system is operating in Closed Loop (conditions must exist for longer than 20 seconds).

Check the wires of the oxygen sensor, making sure they are not in contact with the exhaust manifold.

Check the oxygen sensor and replace if necessary.

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

Check for lean injectors.

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

Check fuel pressure. If pressure is too low, the system will be lean.

Check for exhaust leaks. An exhaust leak can cause air to be pulled into the exhaust and past the sensor.

If you have spark knock, check the EGR system.

Hope this helps.

------------------
fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. Beechwood interior, All original.

IP: Logged
fierofool
Member
Posts: 11747
From: Auburn, Georgia USA
Registered: Jan 2002


Feedback score:    (13)
Leave feedback





Total ratings: 150
Rate this member

Report this Post05-17-2015 12:22 AM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
Was the car up to operating temperature when you actually set the timing?
Did you have the parking brake set and the car in gear when you set the timing? By your statement that "in gear, foot on brake" it's an automatic?
IP: Logged
Csjag
Member
Posts: 3170
From: Ocklawaha,Fl, USA
Registered: Dec 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post05-17-2015 08:37 AM Click Here to See the Profile for CsjagClick Here to Email CsjagSend a Private Message to CsjagEdit/Delete MessageReply w/QuoteDirect Link to This Post
The V6 has a lot of small plastic vacuum lines that could have a small crack and start leaking when warmed up and the cruise control also has vacuum lines that could leak. If you have already checked these good, otherwise I would. The exhaust leak does also affect the idle and what the ecm thinks is happening.
IP: Logged
PFF
System Bot
Shho13
Member
Posts: 820
From: North Jersey
Registered: Feb 2014


Feedback score: (5)
Leave feedback

Rate this member

Report this Post05-17-2015 07:09 PM Click Here to See the Profile for Shho13Click Here to Email Shho13Send a Private Message to Shho13Edit/Delete MessageReply w/QuoteDirect Link to This Post
Out of curiosity, did you change the plugs and wires when you changed your distributor? The heat may be causing weird continuity or resistance issues as the temp goes up. Does it sound like it's misfiring? Also, How are your electrical grounds? You should add an extra ground to wire from your engine block to the body as seen in this thread.

------------------
"Discord"
Red 1988 GT under restoration!

( ͡° ͜ʖ ͡°)

IP: Logged
Rich Truett
Member
Posts: 71
From: Detroit, Michigan USA
Registered: Mar 2015


Feedback score: N/A
Leave feedback

Rate this member

Report this Post05-17-2015 09:47 PM Click Here to See the Profile for Rich TruettClick Here to Email Rich TruettSend a Private Message to Rich TruettEdit/Delete MessageReply w/QuoteDirect Link to This Post
The complete ignition system is new now.
Plugs: AC/Delco
Wires: Fiero store red
Cap/rotor: BWD
ICM: AC Delco
Coil: Standard
IP: Logged
phonedawgz
Member
Posts: 17009
From: Green Bay, WI USA
Registered: Dec 2009


Feedback score:    (23)
Leave feedback





Total ratings: 290
Rate this member

Report this Post05-18-2015 03:23 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Unplug the O2 sensor and see if the problem remains.
IP: Logged

next newest topic | next oldest topic

All times are ET (US)

Post New Topic  Post A Reply
Hop to:

Contact Us | Back To Main Page

Advertizing on PFF | Fiero Parts Vendors
PFF Merchandise | Fiero Gallery | Ogre's Cave
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock