no fire

**Revelation** · 07-13-2017, 11:30 PM

im getting no fire whatsoever from the coil itself on my LT4. could it be the control module or just the coil itself?

**Injuneer** · 07-13-2017, 11:55 PM

Any codes?

Are you getting a signal from the PCM, on the white wire telling the ICM to fire the coil?

http://shbox.com/1/4th_gen_tech2.html#opti_test

**Revelation** · 07-14-2017, 02:40 AM

it got dark so i just came in. ill check that tomarrow. im thinking im gonna have to change that coil and module.

**Revelation** · 07-14-2017, 02:44 AM

it has new a new pcm. the car is 93 but had an engine replacement to a 97 engine so they had to change the pcm as well. but that icm...i found a crack in it and before the coil stopped firing it was jumping fire out of the side of it.

**fullforce** · 07-14-2017, 06:38 AM

Originally Posted by Revelation

it has new a new pcm. the car is 93 but had an engine replacement to a 97 engine so they had to change the pcm as well. but that icm...i found a crack in it and before the coil stopped firing it was jumping fire out of the side of it.

Jumping fire out of the side of the ICM or Coil?

Also an engine swap to a 97 wouldnt require a new PCM infact the 97 PCm was obd2 and used a different wiring harness but the engine were Identical other than the knock sensor and the 97 used a MAF and 93 was speed density.

Nice to see another west TN member

**Injuneer** · 07-14-2017, 10:59 AM

Appears he must have installed the 97 engine, complete with MAF, and also installed the 97 PCM (and likely the 97 harness). That would have caused several interface problems with the body harness connectors, which changed significantly from 93 to 97, issues with the 93 tach, which was driven directly off the coil with a filter.

Info like this needs to be provided UP FRONT with the original post, so it can be considered when offering help.

Also not clear if the spark was jumping out of the ICM (unlikely) or the coil. Need to clarify.

**Revelation** · 07-15-2017, 06:17 PM

the optispark changed between the years. the 93 and 94 where the same. the 95 up was totally different on the backside where it goes into the motor. not only did the 95 up get vented they changed the part that goes into the motor on 95 and up. and the icm are different according to the parts store. hahaha yes good to see a west TN member as well

**Revelation** · 07-15-2017, 06:23 PM

everything has been swapped over to a 97 but thats been some time ago. the car has been running fine until recently when the optispark failed now the coil. harness, pcm and all has been redone or it wouldnt run. lmao. the car started shooting fire out of the side of the coil and then the car suddenly died. after i went back outside i found the coil is cracked down the side as in a weather or heat related crack. ive never had one to do that. but yea it was the coil this time. in which its been 4 years since its had any ignition components replaced such as the coil or distributor