ICM Issues

[Ronnie]

49 minutes ago, Ronnie said:

This is just a shot in the dark but something worth checking...

 

The only logical reason I can think of that the engine will start with the old ICM, and not with the new one, is maybe one of the pins in the ICM connector is broken off and sticking in the old ICM. That might allow the broken pin to make a connection with the old ICM plugged in but not with the new one.

After looking at a photo of the ICM this may not be the problem. Looks like the pins are in the ICM. Oh well...

[Alchemy333]

1 hour ago, Ronnie said:

If the engine will start with the old ICM and not with the ones, I don't see how the ECM could be the problem. The ECM has no way of knowing which ICM is connected to it. If you do the test properly that I recommended, I'm confident that you will find the problem. 

I was thinking maybe it is all running on a default MAP... which refuses to acknowledge new parts and sensors. I did unplug the MAF last night while running, and it didn't shut off of seem to matter at all . But, it did nearly die when I plugged it back in, if that helps.

 

And here are the new and old ICM contacts and connector. There is a missing contact 5th slot from the right. Im figuring it is a non-functioning slot by design... as there is no wire associated on the other side. Are you able to confirm? Or, am I looking at my issue... which wouldn't make sense as to the original functioning and the new one not, to me at least

Edited April 15, 2023 by Alchemy333

[2seater]

Yes, one open slot is correct. 14 pins, 13 wires.

 

When you start the engine, use diagnostics to read some of the data while it is running. Just step through them one by one and record the result. It would be odd to get bad parts over and over, although it does happen. What you really need is parts from a properly operating system. This still sounds much like the Prom failure I had where sometimes just R&R would recover only to fail again.

[Alchemy333]

@2seater im at a no start situation with new ICM. Im gonna call Blue Streak Electronics on Monday. It appears they have GM certified PROMS... flashed and up to date. They also test and reprogram ECMs and PROMs if needed.  I will run the other tests over the weekend though, at ignition on, and see what I can figure out.

[2seater]

6 hours ago, Alchemy333 said:

@2seater im at a no start situation with new ICM. Im gonna call Blue Streak Electronics on Monday. It appears they have GM certified PROMS... flashed and up to date. They also test and reprogram ECMs and PROMs if needed.  I will run the other tests over the weekend though, at ignition on, and see what I can figure out.

If the engine won't run then not much can be gleaned from diagnostics except perhaps the TPS setting. It would be good to know of a source for replacement Memcals (Proms) as the supply is pretty thin. 

The reason I mentioned the integrity of the wiring is because of what I discovered when I took two of the short jumper harnesses from the front of my 1990 LN3 and a 1995 S/C engine. Both had failing loom and as long as they were on the engine stand I pulled them out and removed the loom for replacement. In both cases, I found multiple points where the coating on the actual wires were flaky and sometimes bare for an inch or more. I don't know how long the damage existed or if it was magnified by taking the harness apart, but when two wires that are bare in the same approximate location and are parallel to each other, it gives pause. It is a short harness that connects the knock sensor, cam sensor and crank sensor to the ICM. It connects to the main harness from the firewall on top of the engine just behind the power steering pump. Looking for not only continuity, but also a short to another wire in the harness.

 

Edit: I think it is only the cam and crank sensor connection to the ICM. It is an eight pin plug behind the power steering pump.

Edited April 15, 2023 by 2seater

[Ronnie]

10 hours ago, Ronnie said:

When the engine will not start with the new ICM are the spark plugs getting spark from the coils? That is the first thing you need to know. Next thing you need to know is if the injectors are spraying fuel.

This is the first steps of any no start situation. Can you answer these two questions?

[Alchemy333]

8 hours ago, Ronnie said:

This is the first steps of any no start situation. Can you answer these two questions?

I can answer that before the weekend is through. It sounds like a timing issue to me though. I'm not sure if I can attach video in these posts. But if so I will post with both situations with each of the 2 ICMs installed... and spark/fuel discoveries.

[Padgett]

Are you replacing a Magnavox with a Magnavox or a DELCO (different coils). Does it run with one ICM/coil assembly and not another (Carquest cbj1015 appears to be a Magnavox). Pictures are good. Have you measured the coil resistance ?

 

I always remove the green pad. and tap firmly on the connector ends after screwing in.

Edited April 15, 2023 by Padgett

[Alchemy333]

6 hours ago, Padgett said:

Are you replacing a Magnavox with a Magnavox or a DELCO (different coils). Does it run with one ICM/coil assembly and not another (Carquest cbj1015 appears to be a Magnavox). Pictures are good. Have you measured the coil resistance ?

 

I always remove the green pad. and tap firmly on the connector ends after screwing in.

I havent run the tests yet. Over the weekend here i will. Ive tried three brands ICM now, and have swapped old and new coil pack on all of them. It runs with a miss with the original/old ICM... same with either coil pack, as it was my first hope in resolution. With the newest Carquest ICM, I removed the rubber spacer/seal and secured snuggly... won't even start. Aside from the misfire, I was running it just fine on side streets... but, figure i might as well get this thing top notch.

 

One of my concerns, before I decided to start upgrading engine parts and attempting codes, was the battery had died. I used one of those pocket sized battery jumpers to start the car. It eventually started... but, certainly wasn't happy about it. I feel I may had shorted something out. Being no Ecodes, is one of the reasons I keep leaning towards the ECM. Thoughts? Is there another factor I should be looking at as something that could have been messed up as a result... causing all this confusion?

 

To rehash the work done... new harmonic balancer, air temp sensor, alternator, crank and cam sensor, oil preasure sensor, water pump, radiator, belt, WSS's, BCM pads, front struts, rotors, coil pack, and now we are messing with the ICM and ECM swaps. Reg. Tags 2008 before Nonop... sitting outdoors in a California desert till I grabbed it. Been working on paint correction and repainting the bumpers while waiting on parts and figuring this out.

Edited April 16, 2023 by Alchemy333

[DAVES89]

I would check or replace the crank sensor. I know it's new, but still look at it.

[Padgett]

Are you replacing a Magnavox with a Magnavox or a DELCO (different coils). Does it run with one ICM/coil assembly and not another. If a Magnavox do not gap plugs over .045".

[Alchemy333]

5 hours ago, Padgett said:

Are you replacing a Magnavox with a Magnavox or a DELCO (different coils). Does it run with one ICM/coil assembly and not another. If a Magnavox do not gap plugs over .045".

I see what you are asking. Im running the magnavox setup. I bought Pregapped plugs. After swapping out new plugs, wires and coil, it seemed to run exactly the same... with original ICM. I'll pull a plug and see what they are gapped at though. I already tossed the old guys, which looked factory for any comparison.

[Padgett]

Manual says .060 but Magnavox ICM and coils is not reliable over .045. All of my 3800s have Delco ignitions.

[Alchemy333]

3 hours ago, Padgett said:

Manual says .060 but Magnavox ICM and coils is not reliable over .045. All of my 3800s have Delco ignitions.

Ok. I just got the crank sensor off again. It's under warrantee so grabbing a new guy tomorrow. Seal was also leaking, so that will be replaced. I'll reinstall the new Carquest ICM and re-gap the plugs and report back. Thanx!

[Alchemy333]

Orielly's autoparts had the wrong crank seal in their system (seems to be a thing with the reatta). Had to order the correct one online... so gonna be a while.🤷‍♂️

[2seater]

I went back over the two different but related threads. It appears the apparent issue keeps shifting but some things have never been answered, primarily the crank sensor test now that it was in a no start condition, or simply is fuel or spark lacking? Since the car sat for many years, I would guess there are some items that haven't yet failed or have been masked by apparent ignition issues. Basic things like fuel pressure to start with. Long term storage without being prepped could lead to sticking, non operative or poor spray pattern from the injectors. I would guess it is pretty frustrating to change parts, supposedly new and improved, and yet have worse operation, or none at all. Remanufactured parts should be better than new, but they are made from something that was suspect in the past. That ECM hasn't been produced new for decades. You really need a proven ECM and ICM/coil package to swap in if this continues. It doesn't have to be Cali compliant just to rule out or confirm we are looking in the right place.

[Padgett]

Is a whole diagnosis tree in the Factory Service Manual on "Cranks but does not run".

[DAVES89]

1 hour ago, 2seater said:

I went back over the two different but related threads. It appears the apparent issue keeps shifting but some things have never been answered, primarily the crank sensor test now that it was in a no start condition, or simply is fuel or spark lacking? Since the car sat for many years, I would guess there are some items that haven't yet failed or have been masked by apparent ignition issues. Basic things like fuel pressure to start with. Long term storage without being prepped could lead to sticking, non operative or poor spray pattern from the injectors. I would guess it is pretty frustrating to change parts, supposedly new and improved, and yet have worse operation, or none at all. Remanufactured parts should be better than new, but they are made from something that was suspect in the past. That ECM hasn't been produced new for decades. You really need a proven ECM and ICM/coil package to swap in if this continues. It doesn't have to be Cali compliant just to rule out or confirm we are looking in the right place.

2seater you were at Kendalls with me when we fired up the Red after the engine rebuild. We decided to use the 5000 mile fuel rail and injectors instead of the Red's original fuel rail and injectors. Car would barely run and start. Swapped out the 5000 mile injectors and installed the Red's. Should have done the rail as well as I dealt with dirty injectors for some time after that as the rail was also gunked up.

A lot of issues can be "hidden" from a car that has been sitting...

[Alchemy333]

While I am waiting on the crank seal to arrive, im gonna go ahead and yank the fuel rail and test/clean the injectors. Probably yank the EGR and IAC for thorough cleaning as well. Picked up some MAF cleaner too. Then I will regap the plugs to the .045 spec. too. Im gonna reinstall it all with the new ICM first and take it from there. I'll report back my findings.

 

Edit: when I changed out the fuel filter, there wasn't any sentiment present and the lines were clean. So I hadn't really been overly concerned. Definately worth being run through though.

Edited April 18, 2023 by Alchemy333

[Alchemy333]

Ok... got everything put together again... used the new ICM... regapped plugs to .045... 2nd new crank sensor...starts up for a second rough, spits and coughs, then shuts off. I finally got the E Code E042H. I haven't swapped it out again with the original ICM yet... and would rather not. Im leaning towards the ECM and/or PROM at this point. Thoughts at this point?