Lately my 1985 GT 2.8 has developed a random no-start issue which acts like a bad ICM (no spark or tach signal). Sometimes it will do it on a cold start, other times if the engine has already been running. At first I thought I was eating up ICMs for some reason, but then sometimes it will then start up again. I've even seen it crank for a second with no tach signal, then suddenly catch and fire right up. Sometimes I've fixed it by swapping in a known good ICM, which will fix the problem until next time, but I've swapped in ICMs which I had thought were bad from a previous case of this happening, and it fired right up. And once it's running, it never cuts out. The only thing I can think of is it might be the 2 wire connector between the coil and the ICM. The ignition coil and pickup coil are only a few months old. As noted above, the ICM is one of a few new or good ones I've put in it recently.
ECM can be "dead" and still look good. Bad solder joints anywhere can make engine not start/run but won't set "Codes" because thinks no problems. Example: L4 TBI driver "transistor" can have problems and not turn on even tho ECM command this to happen and won't set codes. Related: See my Cave, ECM Heat
Suggest you clean/fix all ground in engine bay and more and coat ends w/ brake or silicon grease. See my Cave, Wire Service
------------------ 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)
Have you checked the clutch interlock switch? It's near the bend in the clutch pedal. I think you can jumper the yellow and purple wires together to by-pass the switch. BE CAREFUL. CAUTION. DANGER, WILL ROBINSON, doing this will let the car start while in gear.
[This message has been edited by Mike in Sydney (edited 01-23-2021).]
In order for the OP not to get confused by various suggestions, I think it's worthwhile to clarify that the engine is turning over but randomly not starting. This rules out safety switches in Park (with autos) or with the clutch pedal (on manuals).
quote
Originally posted by PatrickTRoof:
Lately my 1985 GT 2.8 has developed a random no-start issue which acts like a bad ICM (no spark or tach signal)... I've even seen it crank for a second with no tach signal, then suddenly catch and fire right up.
I've recently replaced the 4 pin connector to the ICM, as well as the grey connector to the coil (white and pink wires). Next I will replace the white and pink wire connector from the coil to the dizzy, because I just checked it and the white wire has cracked insulation, and it is a replacement.
I just received a Matco ICM tester, and decided to try it on a "bad" ICM (no start or tach signal), but it tested good. I'm really scratching my head now.
Have you checked the clutch interlock switch? It's near the bend in the clutch pedal. I think you can jumper the yellow and purple wires together to by-pass the switch. BE CAREFUL. CAUTION. DANGER, WILL ROBINSON, doing this will let the car start while in gear.
The clutch safety switch only interrupts the starter solenoid trigger signal. Everything else would work, but no crank.
I dealt with a similar issue on my 88GT for a few years and chased a few different things down with no luck.
I eventually replaced the distributor and all my problems went away. (Crosses fingers and knocks on wood) How old is your distributor, cap, rotor?
I replaced the distributor with a newer one that a PFF member sent me a while ago, maybe within the last two years. It only had a few miles on it because he did a 3800SC swap. It's in decent shape. The cap and rotor are less than a year old, as I did my usual tune up recently. I may end up getting a brand new distributor if this keeps up.
Update: the car had been doing fine for a while, though I hadn't been driving it much. Then yesterday it started acting up again. It didn't want to start on the first try, then fired right up on the second.
I drove around doing some errands and it seemed fine. Later I picked up a buddy and we went to work on his Fiero. Leaving there it didn't want to start again. We swapped in the coil connector from his car, with no luck. Put the other one back in and it eventually started.
Later on it wouldn't start at all. I tested the ICM and it was good. So I took a small screwdriver and bent the metal tabs in on the pickup coil connector to make them fit more tightly, and it fired right up.
I don't know if I fixed it or if it just decided to work again. We'll have to see. Next step would be a new dizzy.
PatrickTRoof, Before getting a new dizzy listen to my story. I have a 86 2.8 SE 4spd with a little over 55k at the time of my trouble. It always started but on occasion it would just shut off while driving along in 4 gear but it would always start right back up and run perfectly. I did all the usual checks just short of spending any money and all components of the ignition were okay. I suspected a bad connection between the ICM and the ECM. I started at the ECM harness. With engine running I used a non-conductive item and began poking at each wire on the ECM connectors. At this stage I wasn't even sure what wire(s) were responsible for the ignition. Then it happened, I push against a wire and the engine hesitated but kept running. I teased it some more ever so slightly and was able to stop the engine from running. BINGO!!! I believe it was a white wire on one of the ECM connectors. I pulled the wire from the connector and strengthen up the pin by bending it to fit tighter. Repeated the test and end of problem. That was back in the early 2000's and never had a problem since. A few years ago I did the 3800sc swap and made my own harness so I'd at lease learn a lesson on how things work..
Spoon
------------------ "Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut
I dealt with a similar issue on my 88GT for a few years and chased a few different things down with no luck.
I eventually replaced the distributor and all my problems went away. (Crosses fingers and knocks on wood) How old is your distributor, cap, rotor?
Well, I replaced the distributor and so far the problem has not come back! Thanks for the tip. Now the car fires up immediately, every time, with just a tap of the key. And it sounds better too! The snap crackle pop when I shift gears is so satisfying. Upon closer inspection of the old dizzy, I found metal shavings stuck to the magnet rotor of the dizzy shaft, so that can't have been good. The new distributor has a heavy cast metal magnet rotor and stator, rather than the old stamped metal factory one.
I got one of those new design distirbutors too on ebay. The module was garbage and died within a week, but I replaced it with my good GM one and the distributor has been perfect since.
I got one of those new design distirbutors too on ebay. The module was garbage and died within a week, but I replaced it with my good GM one and the distributor has been perfect since.
Yes, one of the first things I did was put in a good GM module BEFORE it had the chance to fail!
Now I need to replace the 4 pin plug (AGAIN) because it's messed up from changing the ICM 100 times thanks to the old dizzy making me think they were bad! (see my other thread //www.fiero.nl/forum/Forum2/HTML/144919.html )
It never ends...
[This message has been edited by PatrickTRoof (edited 03-23-2021).]
I had intermittent issues that sound exactly like what you are experiencing. I bought new connectors with pigtails to make new cables going to the IGN control module and to the IGN coil.
And these, get the AC Delco ones for these, I had bad luck with aftermarket ones as these are a funky shape and need THICK pins that aftermarket ones are lacking:
I didn't actually end up needing both IGN module connectors, I just needed the ones that go between the ignition coil and the ignition module. I included the 2 pack in the event you need both.
Making the new cable with new connectors solved my intermittent issues for good. I tried multiple solutions first like bending the pins as you have. It really needed new connectors to fully fix the issue.
[This message has been edited by zkhennings (edited 03-26-2021).]
I had intermittent issues that sound exactly like what you are experiencing. I bought new connectors with pigtails to make new cables going to the IGN control module and to the IGN coil.
And these, get the AC Delco ones for these, I had bad luck with aftermarket ones as these are a funky shape and need THICK pins that aftermarket ones are lacking:
I didn't actually end up needing both IGN module connectors, I just needed the ones that go between the ignition coil and the ignition module. I included the 2 pack in the event you need both.
Making the new cable with new connectors solved my intermittent issues for good. I tried multiple solutions first like bending the pins as you have. It really needed new connectors to fully fix the issue.
Thank you for the feedback. I have already replaced all of those same connectors on mine. The new dizzy did the trick for me!