1994 Camaro 3.4 V6 ODB1 TunerPro RT Moates Xtreme ALDL

No... I have not changed the ICM. I was under the impression that the ICM was primarily used during starting, with ignition control being passed to another module above 400 rpm. However, in hindsight the ICM must continue to be an integral part of the process as much of it remains in circuit after startup.

I'll replace the ICM and report back.

Thanks

Update: Ordinarily I try to support my local parts supplier but they (Advance) wanted over $130 bucks for a part I can get online for half that price. I ordered the ICM for $65 bucks and free shipping. I'll have it in 2 days and I'll report back after I install it.

You can use a spark tester in series with the plugs to determine whether or not you have good spark before you replace the module. You can buy a nice one that makes a nice, crisp "snap" sound with each spark. Or you can open a stock plug to .100" to make one. Here's the tester I prefer:


http://www.chevelles.com/techref/hei_files/image010.jpg

beware cheap knockoff ignition control modules, they can leave you stranded, or be dead right out of the box! 65 bucks is certainly a cheap knockoff.

The ICM I bought is about the middle of the road as far as price. It's a "Standard Motor Products" which may not be up to OEM standards (although they claim to be) but it's also nowhere near the $180 to $200 price tag of an original AC Delco part. I'm not even certain that the ICM is the problem but to be honest, if it turns out that it is the problem I wouldn't hesitate to buy the $200 brand and consider the $65 I already spent to be a troubleshooting fee. Why not? I've already dumped enough money into this car that I could have bought another car.

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Originally Posted by Jyuma

It's a "Standard Motor Products" which may not be up to OEM standards (although they claim to be) but it's also nowhere near the $180 to $200 price tag of an original AC Delco part.

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i wouldn't trust that as a sound diagnostic measure either.

i've had tons of standard motor products things fail in short order.

a good parts store can bench test an ICM. napa or whatever. make them test it repeatedly so it gets nice n stressed out.

if you drive there and the engine is already flaking out by the time you get there, as long as you move quickly enough to pull it off of the car and onto the bench, that should be enough to find out in one test.

Well... no joy. I received the ICM I ordered online and it showed up damaged in the box. I returned the part for a full refund and went to my local parts store and shelled out the $150 bucks. Same thing with the new ICM... runs fine when cold but as soon as it warms up it starts to run like crap... like at least 1 cylinder (possibly 2) isn't firing.

Any ideas? I've replaced everything in the ignition circuit short of the crank sensors.

http://www.gearhead-efi.com/Fuel-Inj...ll=1#post55747

hmm..... I've seen crank sensors do something like this before, but generally it would show up in the datalog as wildly swinging RPM values, along with usually showing up on the tach.

Quote:

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Originally Posted by 1project2many

http://www.gearhead-efi.com/Fuel-Inj...ll=1#post55747

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I fully understand your message and will follow your lead. Like I said earlier, I may be getting a bit too analytical with this problem which can sometimes result in overlooking the obvious. Having said that... I already replaced the 3 coils, the ICM, all the plugs, and the wires. Still... your advice is sound.

I'll let you know.

The spark test is important. If you have replaced all those parts and you are still getting no spark then there's likely a problem on the control side of the ICM. If you have plenty of spark you can give up diagnosing a working ignition system and move on to fuel and / or mechanical issues.

It probably doesn't matter now, but I buy Standard and AC Delco parts on a regular basis depending on what's cheaper that day. I've found that many of these parts only differ in the exterior packaging. I don't know that it's the same for all of their parts, but I suspect that Standard is either the original manufacturer or both they and AC Delco buy from the same supplier.

Some folks don't realize tha ACDelco is nothing more than a brand name these days. Delco doesn't make parts, they buy them from a manufacturer.

Problem solved... well, the major problem solved, I've still got problems... like a surging idle... but the major problem of running like crap after warm up is gone.

Turns out at least one of the new plug wires was bad. How do I know? Because I pulled the plug wire off the plug in cylinder 3 and the connector stayed on the plug but the wire was in my hand. That's all I had to see, I went right to the parts supplier and bought another new set of plug wires (better quality).

Anyone who has ever changed passenger side plugs on a 94 Camaro knows what torture is like. You can't even see a few of the plugs on the passenger side let alone get a plug socket on them. So while I was changing the plug wires anyway I also pulled all the (new) plugs and gave them a good inspection. The plug from cylinder 3 was badly carbon fouled, so that leaves little doubt that #3 wasn't firing right. The other plugs all looked pretty good but did show signs of a rich mixture. The other plugs were not bad enough to have been the cause of my problem but #3 definitely was.

So one problem solved but another took it's place. I now have a rough idle with surging. It's probably another sensor or two. I'll let you know.

Thanks for the help.

I know it's five years later to hear this: but, check your engine coolant temperature sensor. It could be 'working' but giving the ECM an incorrect temperature. It sounds like once the o2 sensors warm up enough to allow the engine to go into closed loop and the PCM begins to adjust the pulse width of the injectors to be more efficient, and relys on an accurate reading of the engine's coolant temperature sensor that could possibly be functional, but askew. Just a thought because countless times the: "runs great at first, but runs like crap once it warms up" symptom is usually a ECT sensor or o2 sensor that doesn't fully fail but becomes, 'lazy' or, 'lies' to the ECM