Ok, so I have some weird issues going on and I'm trying to see what else could be going on.

First off, last week, we decided to do some regular maintenance because it had been a while. I ended up replacing all the coil packs, new re-gapped AutoLite 103 plugs, new Duralast ICM. We also have a new SFI balancer set to go on but didn't get it on in time. Decided to drive it as is to the car show and it did great. All was well, parked it over the weekend, came back on Monday to move it and it started acting funky. Was missing out, backfiring, running like junk and the idle was very erratic like shaking at 1,000 or something. I checked the codes and it popped up with a P0336 code. So we figured since we were going to replace the Balancer with the ZZP one and also go ahead and replace the Crankshaft Position Sensor while we were down there. So we did all that, got the new balancer put on and replaced the sensor, start the car runs great. We decided to do the CASE learn the next night and left the car at the shop. Next day, come to start the car, same thing, runs like crap, idling all messed up same 336 code popping up. Now we are stumped.

Question is, we traced the wires, checked the Crankshaft sensor's ground, and the 18x signal going to the ICM with no issues. Next thing could it be a bad or faulty ICM from the parts store? And if so would it still pop up the same Crankshaft code? Do you guys also think it's possible the Camshaft sensor might have took a dump? I'd like to think it's the ICM because it happened before we changed the Crankshaft sensor and it's still popping up after. I'm kind of leaning towards the ICM.

Any thoughts or ideas? Sorry for the long story, but wanted to be sure I explained what was going on.


Thanks guys,
Amir

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Hope this helps. Straight from the GM service manual.

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You said you replaced the ICM, Where is it located on the 1997 3800sc ? Thanks

quote Originally posted by Lou6t4gto: You said you replaced the ICM, Where is it located on the 1997 3800sc ? Thanks

Same place it's located on all the other L67's.

with an engine all tore apart and nothing to "LOOK AT", it is located WHERE ? Thanks

Great Question as I purchased a car with a 3800SC and have no manual on the engine.

I would lean torward a bad coil...I have had more failures from coils on swaps then anything else. Put the coils u pulles off back on and see what happens. Even though u used new parts they can be bad oit the box.

quote Originally posted by MstangsBware: I would lean torward a bad coil...I have had more failures from coils on swaps then anything else. Put the coils u pulles off back on and see what happens. Even though u used new parts they can be bad oit the box.

Yeah we are going to try that and see what happens. The really strange thing is I just got back from the parts store, and my Old ICM that we pulled off was bad. Never even knew and busted off a 11.8 pass with that on there apparently. It never had any starting or any issues misfiring, etc and not even any DTC codes. I am with you on the coils. We are going to pull the new ones off and try the old ones. Is there a way to test them at all or does a parts store have the right equipment to double check them? I had never even replaced them before as the originals were on there or something fairly old. Weird that my car ran fine at the 30th with a faulty ICM the whole time and never popped up a error code.

quote Originally posted by Rare87GT: Yeah we are going to try that and see what happens. The really strange thing is I just got back from the parts store, and my Old ICM that we pulled off was bad. Never even knew and busted off a 11.8 pass with that on there apparently. It never had any starting or any issues misfiring, etc and not even any DTC codes. I am with you on the coils. We are going to pull the new ones off and try the old ones. Is there a way to test them at all or does a parts store have the right equipment to double check them? I had never even replaced them before as the originals were on there or something fairly old. Weird that my car ran fine at the 30th with a faulty ICM the whole time and never popped up a error code.

There is nothing wrong with that ICM and it is not bad or the car would not run as well as it does. The testing they do at the parts store is iffy and most the time is wrong. So hold onto that ICM as my bet is it is still good. Swap back the old parts and go from there. Also stay away from Autozone electrical parts as they seem to have a higher failure rate.

quote Originally posted by MstangsBware: There is nothing wrong with that ICM and it is not bad or the car would not run as well as it does. The testing they do at the parts store is iffy and most the time is wrong. So hold onto that ICM as my bet is it is still good. Swap back the old parts and go from there. Also stay away from Autozone electrical parts as they seem to have a higher failure rate.

Not sure how it worked, but it was tested 3 times on their machine and same result. The new ICM is good and we found that the connection into the grommet was sticking out and not making full contact with the connector. We are going to try it again tonight making sure it has perfect contact. I'll have an update soon. I thought the same thing how in the world did my car even run with a faulty ICM.....

Looks like we figured out the problem. It was the connector going into the ICM. The connector had the grommet sticking out not making good contact with the ICM itself. When we pulled it back apart the grommet got wedged in front of the connector itself. Glad we got it figured out. What a pain. All to install the new SFI Balancer on my car!! Should be back up and going soon. I did however find out my Meiziere electric water pump is leaking slightly, so I'm sending it in to get rebuilt. Should be all back together within a week or two.


Thanks for all the help!