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Old 04-30-2005, 10:11 PM   #1
6speedshifty
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Default Ignition control module/pick-up coil question

I was just wondering what the symptoms of a bad or failing control module would be. I have a '90 L98 with 67,000 miles and it isn't throwing any codes. The car runs fine when its cold, but after driving for a while sometimes the idle suddenly drops and occasionally dies completely. When it does this it won't start again until I let it cool down for 20 minutes or so. Would a partially plugged cat be the problem as well? I'm thinking about just replacing the module and see what happens but I thought I'd get some advice first. Also, is there such a thing as a pick-up coil on these vette's? I had someone tell me it might be the pick-up coil? Thanks for the help.
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Old 04-30-2005, 10:25 PM   #2
JAKE
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That's exactly what happened when my ignition module began to fail. I' was driving down the road and the engine cut off and wouldn't re-start. I let it sit for 20 minutes or so and the engine started as if nothing had happened. I then could drive another 5 miles or so, and the engine shut down again.

I had the module tested at AutoZone and it failed. Just to be sure (I hate to buy parts I don't need) I took it to O'Reilly's and had it tested again. Failed there too. I bought a new one at O'Reily's Auto Parts store and haven't had a problem since; well to be more accurate, I haven't had THAT problem since. LOL

BTW, the one that died one me was a DynaMod, an aftermarked High-Performance module with supposedly longer dwell time, etc.

I'd suggest you do the same and have your's tested.

Jake
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Old 04-30-2005, 10:39 PM   #3
JAKE
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Default

Forgot the pickup coil question.

Up through 89, there is an issue involving the color of the wires on the ignition coil and the pickup coil. Seems to deal with polarity.

If your pickup coil had a yellow wire then the ignition coil must have a yellow wire too. Also, if you look at how those wire are routed you will see that some distributors have the two wires cross each other and some have them running in parallel to each other.

Pull the coil cap off and look at how the coil wire plug into the cap; some cross and others are parallel. Same with the pickup coil. So as I understand it, if the pickup coil wires cross, so too should the coil wires. But just manually crossing them isn't the way to make them match; they have to be designed that way.

In older engines, the color of the wires can become faded and it's really hard to tell whether the wire is white or yellow, using the cross wire reference is a way to determine which is which.

For example, Accel sells two coils for the Vette, one with red and white wires and the other with red and yellow wires.

My engine has one of the 7 prong modules with five pins on one end of the module and two on the other. The pickup coil plugs into the two inner-most prongs on the module.

I don't know if any of this applies to the 90, but you can check the pickup coil with an ohm meter. The pickup coil can fail, but from my experience that isn't too common a problem.

I believe that mis-matching the P/U coil and ignition coil can damage either, both or maybe even the module.

Hope this helps.

Jake
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Old 04-30-2005, 11:05 PM   #4
Vett-eight-nine
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Default car looks good

Just snuck a peak at your gallery, Jake.
Is that new paint? I like the effect on the hood.
Do you have some picks of the rear? (Avatar's a bit fuzzy)
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Old 05-01-2005, 11:52 AM   #5
JAKE
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Quote:
Originally Posted by Vett-eight-nine
Just snuck a peak at your gallery, Jake.
Is that new paint? I like the effect on the hood.
Do you have some picks of the rear? (Avatar's a bit fuzzy)
Click the image to open in full size.

How' this one.

Naw, kinda big isn't it. Let me try another one.

Jake

Last edited by JAKE; 05-01-2005 at 11:54 AM.
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Old 05-01-2005, 12:17 PM   #6
JAKE
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Couldn't figure out how to make them smaller, but here's the front just in case you'd like to see it.

I painted this sucka four times - two different reds then black - before I finally ran out of gas fooling with it. If I never see another can of auto paint it'll be too soon.

Click the image to open in full size.

Jake
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Old 05-01-2005, 12:58 PM   #7
Vett-eight-nine
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Default live life LARGE, Jake

Quote:
Originally Posted by JAKE
Couldn't figure out how to make them smaller, but here's the front just in case you'd like to see it.

I painted this sucka four times - two different reds then black - before I finally ran out of gas fooling with it. If I never see another can of auto paint it'll be too soon.

Click the image to open in full size.

Jake
You did it yourself- I like that.
Good job.
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Old 05-01-2005, 05:38 PM   #8
6speedshifty
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Thanks for the advice. I just ordered a new module that should be here in a few days so hopefully that will solve the problem. Thanks for the info on the pick-up coil. I think I'll start with the module and go from there, it looks like the pick-up is more of a pain to get to and replace.

-Mike
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Old 05-01-2005, 07:36 PM   #9
JAKE
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Quote:
Originally Posted by 6speedshifty
Thanks for the advice. I just ordered a new module that should be here in a few days so hopefully that will solve the problem. Thanks for the info on the pick-up coil. I think I'll start with the module and go from there, it looks like the pick-up is more of a pain to get to and replace.

-Mike
You can test the P/U coil by just removing the cap and rotor, but replacing it calls for pulling the distributor.

Jake
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Old 05-05-2005, 10:49 PM   #10
Photomania
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Default My 1990 six-speed would cut off after 10 minutes

Hi guys,
I just replaced the rotor and the distributor cap today in my 1990 six-speed. Finally, the car is running well again. It was cutting off intermittantly. Sometimes, I could drive it for 60 miles, and it ran fine. Sometimes, it wouldn't run more than 10 minutes.

Several guys on the CF told me that I should consider replacing the ignition control module, as well as the spark plug wires, distributor cap and rotor if I hadn't replaced those. First, I replaced the ignition module and the car still cut off after 10 minutes. It wouldn't start up until it sat for a while and cooled off, even with the new IM.

While replacing the ignition module, I noticed that the rotor had a light dusting of black particles. I also noticed pieces of metal in the bowl of the rotor. These turned out to be the disintegrated rotor contact. So, I ordered a new rotor and a new distributor cap.

While mounting the old ignition coil to the new distributor cap, I noticed that the bottom of ignition coil was covered with light rust, and I cleaned that and coated it with dielectric grease.

I drove the car 12 miles today, and it never cut off or even stumbled. I stopped and backed up repeatedly and even drove 75 mph. It did fine. Tomorrow may be a different story. But I'm hoping this has brought to an end weeks of stumbling and stall-outs and being temporarily stranded. -- Eric
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Old 05-05-2005, 10:53 PM   #11
JAKE
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I'm glad to see that you problem was fixed. Hope that's all it was, the module. I'll keep my fingers crossed for you.

Jake
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Old 05-08-2005, 04:18 PM   #12
LT1_Polo
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Default Ignition Module

I am getting ready to replace the ignition module on my '95 LT1 and was wondering if there was a specific brand anyone recommended, either for or against? Any horror stories or anyone been exceptionally pleased with a certain brand? Not looking for anything with longer dwell or higher performance right now, just want to get rid of the stumbling. Thanks...
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Old 05-08-2005, 05:42 PM   #13
86PACER
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Quote:
Originally Posted by JAKE
I' was driving down the road and the engine cut off and wouldn't re-start. I let it sit for 20 minutes or so and the engine started as if nothing had happened.


Jake
Same thing happened to me going about 55-60 MPH. Lost power steering and was barely able to coast off the side of the road into a gas station parking lot without going into a ditch. Mine never started up again, it would only crank over but not fire up. Had to get it towed back home, and it turned out to be the pick up coil inside the distributor.
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Last edited by 86PACER; 05-08-2005 at 05:46 PM.
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Old 05-08-2005, 05:49 PM   #14
86PACER
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Quote:
Originally Posted by JAKE
You can test the P/U coil by just removing the cap and rotor, but replacing it calls for pulling the distributor.

Jake
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Old 05-08-2005, 07:53 PM   #15
JAKE
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Quote:
Originally Posted by LT1_Polo
I am getting ready to replace the ignition module on my '95 LT1 and was wondering if there was a specific brand anyone recommended, either for or against? Any horror stories or anyone been exceptionally pleased with a certain brand? Not looking for anything with longer dwell or higher performance right now, just want to get rid of the stumbling. Thanks...
The one that died on me was a DynoMod so definitely stay away from that one.

I believe Accel has a module with a built-in over-heating protection circuit. Either that one or a factory module; who makes 'em AC-Delco?

Jake
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Old 05-10-2005, 12:16 AM   #16
LT1_Polo
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Default Thanks

Thanks for the heads-up on the module. Got a factory replacement, helped with the problem but did not cure. Have put a new coil and new module on, looking to do plugs and wires later this week. Anything else besides an Opti-Coil I should consider for these problems? (Stuttering, sometimes sounds like a miss on several cylinders, stumbling at random times, but not dying any more.) Thanks again...
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Old 05-10-2005, 12:16 AM
 
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