How to check 84 Coil (Page 1/1)
ascii23 JUL 24, 01:24 PM
So I think my coil failed, I believe my ICM Works, I have a check engine light, and the pickup coil reads good on a multimeter, but I still have no spark, I took the coil out, and I think the coil fails the tests set out in previous threads, the coil output stud reads open to any of the contacts on the connector, but I'm not sure because I know the 84 coil is different from the 85+ coils.
Patrick JUL 24, 03:12 PM

quote
Originally posted by ascii23:

I know the 84 coil is different from the 85+ coils.



Although the connections are different on the '84 coil, I believe internally it's no different than the later coils. The same tests/results should apply.
theogre JUL 24, 04:58 PM
Not sure exact 84 coil test but HEI and DIS coil testing w/ any standard meter can pass GM tests and still be bad.
Primary Ω test is under a few Ω and most can't read that reliably. More so w/ digital meters that won't allow you to 0 out the probes etc.
High Volt can short out many winding and still read ok to any normal meter.

Example: Many book list all HEI from 1981-90
Primary Ω is 0 - 2 Ω
Secondary is 6,000 to 30,000 Ω

Plus many have crap plugs, plug wires, etc, that can cause HV to blow thru coil insulation inside. Many will test ok but is dead and can kill ICM etc too.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

ascii23 JUL 24, 08:15 PM

quote
Originally posted by Patrick:

Although the connections are different on the '84 coil, I believe internally it's no different than the later coils. The same tests/results should apply.



Okay, I bought another coil because they are cheap, I'll see if that fixes my no spark issue.
ascii23 JUL 24, 08:16 PM

quote
Originally posted by theogre:

Not sure exact 84 coil test but HEI and DIS coil testing w/ any standard meter can pass GM tests and still be bad.
Primary Ω test is under a few Ω and most can't read that reliably. More so w/ digital meters that won't allow you to 0 out the probes etc.
High Volt can short out many winding and still read ok to any normal meter.

Example: Many book list all HEI from 1981-90
Primary Ω is 0 - 2 Ω
Secondary is 6,000 to 30,000 Ω

Plus many have crap plugs, plug wires, etc, that can cause HV to blow thru coil insulation inside. Many will test ok but is dead and can kill ICM etc too.




Ok, but it failed one of the tests, can it fail the test and still be good?
CSM842M4 JUL 24, 09:19 PM
I believe you would be far more likely to see a false "good" than a false "bad". In other words, like theogre stated, you can have a coil "pass" an ohm test and still be bad, whereas if it fails an ohm test, it's not likely to perform differently (better) when installed. Just my $0.02, your mileage may vary.