I've been battling a code 42 on my 87 coupe since I purchased and resurrected the car a couple of months ago. It had been sitting since 2012.
On my first drive the car gave me a bunch of codes including code 42.
I've changed the coolant temp sensor and the Manifold absolute pressure sensor and that took care of those codes.
I put in fresh plugs, ignition cables and filters when I got the car. The code 42 seemed to of been a hesitation under acceleration. Now I've changed one of the coil packs that I thought was dead and it didn't change anything. I changed the crank sensor and that didn't change anything. I changed the Ignition Control Module and that didn't change anything. Actually, it seems to have gotten worse as now it seems the be running rough when it wasn't before.
I've done as the Orgre mentions and added the silicone grease between the ignition control module and the metal bracket and I made sure to transfer the heat shield on the new Ignition control module.
I'm kind of at a loss now and I'm not to sure what to do next, Any suggestions?
I've checked and cleaned the grounds on the bolt near the ignition modules, so I suppose I should follow the wires to the ECM and see if there is a break anywhere?
I hope that is not the case however I will swap out the Ignition Control Module for the old one and test that out to make sure I didn't buy a defective Control Module.
Check/clean/fix ALL grounds in engine bay. Try Again.
Then...
Discon ECM "reset" in engine bay. Check/fix Ground screw below ECM. Unplug and re-plug ECM connectors a couple of times. That can clean the contacts. Plug Reset and try again.
Could be bad ECM or need a new PROM. See my Cave, 87-88 DIS Duke ECM If need a new PROM might be hard to get. try www.bsecorp.com to get email or call special-order dept.
------------------ 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)
After you have checked (and added to) all grounds and verified the ECM wiring is intact: I’ve had that with new plug wires still arcing to the engine and causing hesitation during acceleration. Are the original plug wire holders still in place and are you using them? Even using the original plug wire holders I’ve had to adjust the wires so they are not against any metal. To find my problem I started the car in the dark at night and looked for arcing from the wires.
Originally posted by mike-ohio: After you have checked (and added to) all grounds and verified the ECM wiring is intact: I’ve had that with new plug wires still arcing to the engine and causing hesitation during acceleration. Are the original plug wire holders still in place and are you using them? Even using the original plug wire holders I’ve had to adjust the wires so they are not against any metal. To find my problem I started the car in the dark at night and looked for arcing from the wires.
Good brands of wires won't care if wire touches or close to metal. Using OE wire loom parts are fine too when used w/ 7mm and some 8mm wire sets. If you have problem w/ new wires then return for a refund.
Good wires can go bad, some very fast, if you spill/spray oil coolant or solvents on the wires.
Ok well I finally had some free time to work on the car today, I swapped the old Ignition control module onto the car and it no longer idles rough so I guess the new module was defective. The check engine is still lit but I have yet to take it for a spin. I will report back shortly with more info.
Now I did notice that I installed BOSCH plugs and the Ogre says NO bosch plugs. I have no clue if they are platinum plus or regular plugs they were on clearance at rock auto and I figured I'd pick them up. Do you guys think I should change them for a different brand if the check engine is still lit?
The wires at the connector for the ignition control module seem fine, one of the wires on the bottom switch of the ignition module was previously repaired but when I played with it with the car running I didn't notice any difference.
I don't have the OEM ignition cable aluminum holders for the car, they weren't on it when I bought it but the wires seem fine from what I can see.
I cleaned both the grounds on the left of the ignition control module. Where is the other ground?
[This message has been edited by FieroMontreal (edited 09-15-2015).]
Between 1985 and around 1998, have always had problems with platinum plugs on GM cars with waste spark(2 plugs per coil) coil packs. And not just Bosch. Even with the dual platinum, that were supposed to do away with the problem. Either standard or iridium on waste spark coils. On GM, I insist on AC Delco, NGK or Denso. Also stay away from trend plugs(split fire, diamond fire, multispark) Have also seen issues with Ford multi pack coils with platinum. On those we get a phantom misfire code. However don't seem to have that issue with coil over plug ignition.
Originally posted by FieroMontreal: Now I did notice that I installed BOSCH plugs and the Ogre says NO bosch plugs. I have no clue if they are platinum plus or regular plugs they were on clearance at rock auto and I figured I'd pick them up. Do you guys think I should change them for a different brand if the check engine is still lit?
Just check RA paper or Pull a plug to check # of plug. Bosch +2 and +4 are known to have problems because thin center electrode when used on GM DIS engines.
quote
Originally posted by cmechmann: Between 1985 and around 1998, have always had problems with platinum plugs on GM cars with waste spark(2 plugs per coil) coil packs. And not just Bosch. Even with the dual platinum, that were supposed to do away with the problem. Either standard or iridium on waste spark coils. On GM, I insist on AC Delco, NGK or Denso. Also stay away from trend plugs(split fire, diamond fire, multispark)
I use normal Autolite and AP666/APP666 "double platinum" plugs for years w/ no problems. (APP has nickle plated Shell that won't rust and 5y warranty. AP is 3y warranty.)
Splitfire got sue by FTC for BS claims. Many others are making same BS claims now.
Just check RA paper or Pull a plug to check # of plug. Bosch +2 and +4 are known to have problems because thin center electrode when used on GM DIS engines.
I looked at the Rock Auto invoice, it just mentions "BOSCH 7576 SUPER". When I click the info button it says "v-profile nickel chromium ground electrode" so I assume I am ok on that front.
[This message has been edited by FieroMontreal (edited 09-16-2015).]
Should be... New plug(s) could be bad or Iffy plug wires or coils. (Bosch discontinued 7576 SUPER.)
DTC 42 is mostly problem w/ ECM/ICM connections or ground(s).
Crappy parts on high volt (secondary side) of system often don't cause DTC 42. Bad Coil(s) might if it shorted between primary and HV. That can "fry" the ICM too. See http://www.wellsve.com/advantage_dis.html
Bad plugs or plug wires can kill the coil then bad coil can kill the ICM. This is why when you think a coil has problems then always replace the plugs wires and plugs. (HEI cap and rotor too.)
Ok well I took the car for a test drive for the first time since writing this thread.
When I plugged in the old Ignition Control module the check engine went away. I changed the plug wires for a 2nd set ..just in case.
I went back for a drive today and the check engine came back.
The car idles well, no more problem there. The car does not drive well. Feels heavily under powered and hesitates a lot.
So to resume. New Plugs, New Wires (again), 1 new coil.
I'm thinking of ordering another new coil to replace the 2nd one... and possibly another ignition control module since the other new one was defective I never really got the chance to see if a new one would solve the issue.
I don't have an autozone near me, is there a way I could test the control module myself with a multimeter or check for resistance like an injector?
I know you keep mentioning grounds in all the topics I read but the two grounds next to the ICM seem fine, I did clean them too. You did mention a 3rd ground to the ECM, where is this one located? I saw one near the decklid but it looked more like an engine ground.
The plugs on the ICM seem ok too but other then play with them I'm not sure what else I could do to make sure that they are ok. I have plugged them in and out several times.
[This message has been edited by FieroMontreal (edited 09-17-2015).]
I installed new plugs in the car and went for a spin on the highway for the first time. The car died even though it was driving fine, I believe the coils over heated as the car started up again about 20 minutes later.
I installed 2 brand new standard motor coil packs. The car purrs like a kitten but still has a code 42.
When cold I have a serious hesitation at low RPM around the 2000rpm as if I had a moment without power and then it comes back all at once. It feels like when you are about to stall the car and it only happens when you take off and the engine is cold. As soon as the car is warms up, it runs perfectly at all RPM ranges.
So to recap the current set up
New Autolite copper plugs 2 New standard Motor Coil Packs A new set of BW ignition cables A new old stock ACdelco Ignition control module New Coolant sensor, MAP and MAT and Crank sensor
The ground on the engine block was cleaned up and is good. I have no clue where the second ground should be. The car did develop a small coolant leak from the quick connect on the intake, that was resolved as soon as I saw it.
I have taken the car on long rides with the new Coils and it has not died on me like it did with the previous coils. It seems there's something that doesn't want to work well when it's cold, I'm just not sure what.
[This message has been edited by FieroMontreal (edited 10-26-2015).]
Originally posted by FieroMontreal: the silicone grease between the ignition control module and the metal bracket and I made sure to transfer the heat shield on the new Ignition control module.
It's supposed to be heat sink compound, not grease. Some ICM's come with a little tube of white heat sink compound, but if it didn't, get some at a computer supply store, such as Microcenter or Frys.
But if you have an 87 duke, I don't think heat sink compound is required on those. For one thing, there's nothing for the heat to be transferred to. The metal plate between the ICM and the coils is a magnetic shield, not a heat sink. It has to be there, or you will have trouble.
Check the connectors that go to the ICM. If they are corroded or dirty, that could be your problem.
Sorry I forgot to mention that I purchased the proper grease and installed it between the bracket and the NOS Ignition control module however not between the shield and the Ignition control module
[This message has been edited by FieroMontreal (edited 10-26-2015).]
The mounting tray is the heatsink of the PIM. (Later versions have fins.) GM install ICM Dry. I use a bit of silicon grease to keep water/dirt/salt away from this area.
Heatsink grease can cause problems... Main reason is the area where two parts meet is huge. Most compounds won't squeeze out the excess for this reason.
You must use a very thin coat of grease.
DTC 42 likely still have wire/ground problems in ECM-ICM wires or you need a another PROM in the ECM. Reread post above...
I will ONLY run AC-Delco plugs in a GM car, it is what the engine is designed on. Code 42 you get is an odd one, sounds like a break in wire, and as heat/cold contracts and expands wires, I could see this, I have had where the ground wire was loose in the ring terminal, I have had where spark plug wires were fine cold but once heated up the boots leak spark, at night, in the dark, look for arcing, mist the plug wires with water from a spray bottle as it will amplify spark leak. Have someone try to put a load on the engine and look again. Cheap plug wires will leak spark right out of the box, I use Taylor wires now (since Jacobs went under) Coils rarely go bad, I even had a coil with a break in one of the windings work perfectly fine. There is no way to test an ICM with out a machine to test it. That is all the questions I remember reading in this post.
OK never saw you post if you had checked or replaced you pickup coil, I think it was code 42 I got intermittently when I had that go. Look at it and see if the tape around the coil is worn and the wires are rusted or if where they connect is broken. Mine would run great on sunny days and if it was high humidity or raining it ran like crap. But even on a sunny day if I hit a small bump it would also run like crap, hesitation.
Check that out, it may be that.
Steve
------------------ Technology is great when it works, and one big pain in the ass when it doesn't
I've checked and cleaned the grounds on the bolt near the ignition modules, so I suppose I should follow the wires to the ECM and see if there is a break anywhere?
I had this problem with a broken wire. The engine would be purring fine and when I press the clutch the car would stumble and set a code 42. I was perplexed until I realized that the clutch arm was causing a wire bundle to move just a little. I could wiggle the wire and have it stumble on command.
OK never saw you post if you had checked or replaced you pickup coil, I think it was code 42 I got intermittently when I had that go. Look at it and see if the tape around the coil is worn and the wires are rusted or if where they connect is broken. Mine would run great on sunny days and if it was high humidity or raining it ran like crap. But even on a sunny day if I hit a small bump it would also run like crap, hesitation.
Check that out, it may be that.
Steve
There is no pick up coil, it is DIS
quote
Originally posted by jscott1:
I had this problem with a broken wire. The engine would be purring fine and when I press the clutch the car would stumble and set a code 42. I was perplexed until I realized that the clutch arm was causing a wire bundle to move just a little. I could wiggle the wire and have it stumble on command.
Sound advice, shake the entire harness, roughly, while idling and see what happens.
[This message has been edited by sardonyx247 (edited 10-28-2015).]
Summer season is back and I've woken up the car again. I still have the same issue with the car. I replaced the ICM again for the 3rd time and it's a no go.
I've been looking for a PROM chip. The only possible source I found was CARDONE however after lengthy discussions with their techs directly at cardone they no longer offer the PROM that I require. They initially told me they offered it but when it came time to order it they came back to me a few days later saying it is no longer available.
I had a look at the Bluestreak website as it was previously mentioned on the forums but they don't have a listing either.
Try this... get your hands on a used ignition module unit (entire unit) and coil packs. Beg, borrow, purchase. Install those. If problem persists, start car and start yanking on wiring as it is running. If you think it is the computer, just beg, borrow, purchase a used computer. Swap out known good parts and see where that leads. If problem goes away, you have your issue.
Otherwise, take it to a shop and they can scan it while running to get some data and work from there.
I replace the PROM with another PROM with the same part #. Although the car runs smooth at idle I still have the hesitation and struggle around the 2000rpm mark and when the car is cold. When it's cold it literally feels like everything cuts out when I give it gas, if I let it warm up or hit the gas pedal a couple of times before leaving it's better.
I still have one pigtail to replace on the ICM. I will hopefully do that soon.
My tach stopped working today on my drive to work, no clue what could cause that to happen either.
[This message has been edited by FieroMontreal (edited 07-20-2016).]
On the tach, could be another intermittent wire (groan). Mine will cut out, but if I rap on the housing hard it just starts working again. I can also rap on it and make it stop working. Imagine that.
This generation of ECM is prone to shrinkage of the circuit board coating, which basically rips off the components' metallisation. The shrinkage is microscopic, so you can't see it.
I've had the same problem on my 87 L4, and the cause was a filter capacitor in the EST circuit losing its metallisation. AFAIK GM never officially acknowledged this problem, they only got as far as "if you tap on the case and it sets a code, replace ECM". But some rebuilders explain this is why they remove the conformal coating and replace a number of components. It was common when GM switched to surface mounted components in the mid-eighties.
Like I said, I had the same problem, replaced the ECM, and bang - Code 42 gone.After knowing it's the ECM, I further looked into what sets the code (there are two separate reasons for a Code 42 in the ECM program, one being no pulses from the DIS module, the other being extraneous pulses from the DIS module, which is what happened in my case. Then I took a closer look at the filter circuits, located the capacitors and started to resolder them. One of them immediately lost its contact metallisation as the solder melted. Replaced it with a 100nF capacitor, and the ECM has been working again without Code 42 after that!
If the problem is the PROM... Replacing w/ same # won't work. Try phonedawgz tk etc that make/made PROMs to find update PROM. You don't want any "performance changes," just update code in connect EPROM. (Correct # is 27x128. x can be 1-2 letters. ref: http://www.exatorq.com/ludi.../p4xref.html#1227748 )
"Prom code ACMH 9544" then you need 3563ATBS as posted in my cave link above. AC/GM part # 16143453 https://www.google.com/#q=GM+part+16143453 have many listings but not in stock
quote
Originally posted by fieroluke: Have you replaced the ECM?
This generation of ECM is prone to shrinkage of the circuit board coating, which basically rips off the components' metallisation. The shrinkage is microscopic, so you can't see it.
I've had the same problem on my 87 L4, and the cause was a filter capacitor in the EST circuit losing its metallisation. AFAIK GM never officially acknowledged this problem, they only got as far as "if you tap on the case and it sets a code, replace ECM". But some rebuilders explain this is why they remove the conformal coating and replace a number of components. It was common when GM switched to surface mounted components in the mid-eighties.
Like I said, I had the same problem, replaced the ECM, and bang - Code 42 gone.After knowing it's the ECM, I further looked into what sets the code (there are two separate reasons for a Code 42 in the ECM program, one being no pulses from the DIS module, the other being extraneous pulses from the DIS module, which is what happened in my case. Then I took a closer look at the filter circuits, located the capacitors and started to resolder them. One of them immediately lost its contact metallisation as the solder melted. Replaced it with a 100nF capacitor, and the ECM has been working again without Code 42 after that!
Is called "Conformal Coating" and GM did had problems w/ many ECM because of this. Actually the problem was cause by CC Swelling for interaction w/ Moisture in the long term and breaking parts of the board. (Worse near the oceans etc.) Very old Cardone TSB cover this but can't find a copy right now.
Fiero ECM have heat problems because of location and console insulation. See https://www.fiero.nl/forum/Forum2/HTML/138143.html Remove the console to test may help but if it does... Still need to replace ECM because damage can/will come back. Tapping ECM w/ fingers may help too (Tapping to vibrate iffy parts on the board.) but if it works, same thing... need new ECM.
CARDONE Corrects GM ECM Surface Mount Problem Application: G.M. Electronic Control Computers with surface mount technology. Original part numbers are:16156647, 1227165, 1227303, 1227727, 1227730, 1227748, 1227749, 1228253, 1228321, 1228547, 1228706, and 16149396. (1227748 For 87-88 Fiero 4 cyl) Problem: Engine misfire, hesitation, and intermittent check engine light and stalling. And bogus DTC. (Error/Sensor Codes) Cause: The original conformal coating applied by G.M. swelled, causing movement of the electronic components and cracking of critical solder joints. Solution: In 1994, a new process was introduced into production by CARDONE. The original conformal coating is removed, then the components on the printed circuit board are resoldered and tested. Finally, a new formula conformal coating is applied to seal the circuit board to complete the process. Note: CARDONE Electronic Control Computer part numbers with the updated process are: 77-6647, 77-7165, 77-7303, 77-7727, 77-7730, 77-7748, 77-7749, 77-8253, 77-8321, 77-8547, 77-8706 and 77-9396.
Older copy of above or maybe old stories in Motor! and other trade rags said CC would swell over time for moisture absorption.
[This message has been edited by theogre (edited 07-21-2016).]
On the tach, could be another intermittent wire (groan). Mine will cut out, but if I rap on the housing hard it just starts working again. I can also rap on it and make it stop working. Imagine that.
The Tach fixed itself on the way home from work so it mut be a bad connection.
quote
Originally posted by fieroluke:
Have you replaced the ECM?
This generation of ECM is prone to shrinkage of the circuit board coating, which basically rips off the components' metallisation. The shrinkage is microscopic, so you can't see it.
Thanks for the info I was not aware. I only changed the PROM however the replacement prom did come with a ECM. I will but the PROM back in it's ECM and give it a go that way!
If the problem is the PROM... Replacing w/ same # won't work. Try phonedawgz tk etc that make/made PROMs to find update PROM. You don't want any "performance changes," just update code in connect EPROM. (Correct # is 27x128. x can be 1-2 letters. ref: http://www.exatorq.com/ludi.../p4xref.html#1227748 )
"Prom code ACMH 9544" then you need 3563ATBS as posted in my cave link above. AC/GM part # 16143453 https://www.google.com/#q=GM+part+16143453 have many listings but not in stock
TheOgre, I am not following.
If the original PROM from the factory is ACMH 9544 and it is now faulty, shouldn't I replace it with another ACMH 9544 that will have the same original programming without the fault in the chip?
As I mentioned earlier in the topic, I have tried getting a new prom through various sources, GM, blue streak, cardone etc and no one makes or has any more of these so my only option was used.
[This message has been edited by FieroMontreal (edited 07-21-2016).]
Originally posted by FieroMontreal: 1. TheOgre, I am not following.
2. If the original PROM from the factory is ACMH 9544 and it is now faulty, shouldn't I replace it with another ACMH 9544 that will have the same original programming without the fault in the chip?
3. As I mentioned earlier in the topic, I have tried getting a new prom through various sources, GM, blue streak, cardone etc and no one makes or has any more of these so my only option was used.
1. Re-Read this entire thread and my cave links. 2. NOT the PROM is "bad." The "Program" in it is "bad" and PROM w/ same # likely won't help. 3a. If you ordered a new PROM from ACdelco etc You Would Get 3563ATBS. They only carried update PROMs. 3b. Names right above and Darth Fiero are just 3 PFF members that make PROMs. They might have updated PROM files and could make one for $. How much? ask them. AC, GM Dealers, etc, would get $30 or more.
When you switch ECM might fix the problem or not. If not then get 3563ATBS PROM. Still have problem then at least you know is not a PROM. Remove some console insulation over ECM too as said in above link and my cave.
[This message has been edited by theogre (edited 07-22-2016).]
