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how to test coils


no1kicker

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I have my coils / ICM off now. I know I have to check for resistance. Can someone explain the procedure? Like which is the primary / secondary side?

 

:?

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Don't let anybody bull shit you. The only way to test coils is to repalce one at a time to find out which one is bad. Resistance cold dosent mean anything. Coils break down with heat and cannnnnnnnooott be tested with resistance, period.

 

Resistance can tell you if it is flat out dead but can't tell you under operating conditions. So screw the resistance replace one at a time. You only need one known good one to do this.

 

Jesse do a search. Surely you have seen this before. You have been here long enough. It's been posted several times. :roll:

 

Yea this subject pisses me off.

:evil:

Jud

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All my coils are belong to you :( :P

 

:lol:

 

 

Jud if the resistance thing is true, than I won't bother. I'm getting the ICM tested this week so I can rule that out. If that's fine then I'll just replace the coils. (assuming the spare ICM / coils make the car better.) I did a search but all I found was "I think they should be this" and the likes. In the factory book it doesn't say either. I just remember the TA repair book shows you which pins to measure from, and what it should be.

 

This subject pisses me off too. Especially that 3rd bolt on the bottom of the coils. :evil:

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Yeah you may want to consider not putting that 3rd bolt back in.. :lol:

 

When you have the ICM tested have them do it at least 3 times, maybe more to make sure that it doesn't fail intermittently or when it gets hot.. but Jud is right, the best way to test coils is one at a time by replacing them. I tried that method, had a bad coil, didn't show anything when testing resistence. Are you having issues with misfiring or skipping?

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All my coils are belong to you :( :P

 

:lol:

 

 

Jud if the resistance thing is true, than I won't bother. I'm getting the ICM tested this week so I can rule that out. If that's fine then I'll just replace the coils. (assuming the spare ICM / coils make the car better.) I did a search but all I found was "I think they should be this" and the likes. In the factory book it doesn't say either. I just remember the TA repair book shows you which pins to measure from, and what it should be.

 

This subject pisses me off too. Especially that 3rd bolt on the bottom of the coils. :evil:

 

Leave the bolt out you don't need it.

 

You can check resistance but it may not tell you if its bad. :cry: Coils break down more frequently when there hot and under load, that's why I said replace one at a time. This will tell you the exact bad coil and save you $65. You can just let the icm and coils hang so you can get the coils off eaiser to change one at a time. (position it so you don't burn the wires or it gets in the fan. Its got its own ground. Drive the car and repeat the condition it missed before.

 

If its missing at an idle constantly you can check with a timing light, spark tester or probe.

 

Regarding your question about checking. primary(side that plugs in to your icm .50-.90 ohm's, Secondary(plug wire side) 5000-10,000 ohm's. Eaist to use a tester with auto range.

 

When you check the icm be carefull they make there money selling parts and there expensive. When you have yours checked and they say it failed have them check a new one. Also have them test it several times to warm it up good. I have two icms that failed on thoes machines. I didn't believe it so I went to another store and the tested ok. Saved $120. I still have the orginial one on my car but I have been through about 8-10 coils.

 

Good luck.

 

Jud

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how to test coil packs:

 

1: pick up suspect coil

2: find your Scientific wall of learning (preferably made out of brick)

3: fling coil pack as hard as you can at wall

4: look at broken coil, observe its brokeness

5: you have a broken coil

6: replace broken coil

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Cool. Thanks for the info. My car was sluggish and sounded like it was backfiring. Friday it started to run on 4 cyl's. I put the spare ICM and coils in and the car is 100% now. But the spare is Tony's (gutless). One of the coils looked like it wasn't firing when I took it off, the one on the left.

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I'm going to have the ICM tested. I called advance auto and they said they test "some". I'm hoping this is common enough to be able to be tested there.

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should be, they do them here in town.. also try Autozone or maybe even Carquest/Napa. These are fairly popular ICM's as they went in many different GM cars.. hell I think I saw the same thing in a Honda SUV today.. :shock:

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  • 2 months later...

With the DOHC, what's the best way you all have found to get to the coils and replace them? I have some replacement MSDs I wanna throw in (got them VERY cheap, hence why i'm putting them in) but since they're by/behind the starter and in front of/blocked by the exhaust manifold..i'm kinda stumped. What size bolts to remove them? Sorry to hijack the thread by the way :oops:

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