Need Help 94 Ignition
Thread Starter
Burning Brakes
Joined: Mar 2001
Posts: 1,228
Likes: 16
From: Mansfield Texas
Need Help 94 Ignition
Trying to fire rebuilt LT1, new opti-spark and I'm getting fire at the coil but not at the end of the coil wire with a test light and it does not spark, no spark at the spark plug itself. I tried a 2nd coil and coil wire as a back-up and still the same. I replaced the ground strap off the harness near the coil as well. Any ideas?
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Just to be sure, you are getting spark at the coil, but nothing at the end of the wire. That's odd.
I wonder if the coil is getting enough juice to overcome the resistance. Check the various wiring to the coil and ICM. Do you have a spare ICM to swap and test with?
I wonder if the coil is getting enough juice to overcome the resistance. Check the various wiring to the coil and ICM. Do you have a spare ICM to swap and test with?
Thread Starter
Burning Brakes
Joined: Mar 2001
Posts: 1,228
Likes: 16
From: Mansfield Texas
Battery charger is on the battery so I'm getting full juice. Yes, I have a spare ICM/Coil/Coil Wire that I tried and nothing. Opti is triggering the ICM and Coil but not the cap and wires/plugs. It pops intermittently like it is getting some fire but not enough to start.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
If you are really getting proper spark at the coil wire, you should be able to pull about a 1/2 inch spark. Anything much less is not enough. Assuming you have a good spark, there is a possibility the opti is mis-aligned on the drive shaft. Even if so, the spark should come out somewhere on the wires but who knows. The opti should have just fallen on the front cover with a tink when installed. The bolts should just hold the opti in place but should not pull it to the cover. It should hit and be flush imminently. Re-check the notch on the spine to make sure it’s lined up properly.
The other thing I could think of is remove the opti cap just to make sure the rotor and cap looks OK.
If spark looks weak, I agree to check the ICM for a problem. The 5 VAC drive pulse from the PCM is probably OK since you have some sort of spark so I would not concern myself with that at this time.
The other thing I could think of is remove the opti cap just to make sure the rotor and cap looks OK.
If spark looks weak, I agree to check the ICM for a problem. The 5 VAC drive pulse from the PCM is probably OK since you have some sort of spark so I would not concern myself with that at this time.
Thread Starter
Burning Brakes
Joined: Mar 2001
Posts: 1,228
Likes: 16
From: Mansfield Texas
Ok let me check for the opti being mis-aligned. It went on with a little push but did not fit flush probably lacked a 1/4" or so but went straight on with the bolts, I will take it back off and see if I can get it to go on like you said, would that cause a weak spark at the coil? I tried (2) different ICM's thus far and the spark is the same.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
If miss-aligned, it would not cause a weak spark at the coil. But will affect the spark at the plug wires.
Turn engine till notch is at 12:00 when shaft is in engine. Then make sure notch is at 12:00 on opti and install gently. The “O” ring will give it a slight resistance, but will then release and it should hit the cover firmly. A ¼ inch is not right before bolts are installed.
Start engine before water pump is installed. Temporally install TB intake and connect pump temp sensor. Just lay on top of TB, wires will reach. Can run to make sure it’s OK, 30 seconds or so. Then put everything together properly.
Turn engine till notch is at 12:00 when shaft is in engine. Then make sure notch is at 12:00 on opti and install gently. The “O” ring will give it a slight resistance, but will then release and it should hit the cover firmly. A ¼ inch is not right before bolts are installed.
Start engine before water pump is installed. Temporally install TB intake and connect pump temp sensor. Just lay on top of TB, wires will reach. Can run to make sure it’s OK, 30 seconds or so. Then put everything together properly.
Thread Starter
Burning Brakes
Joined: Mar 2001
Posts: 1,228
Likes: 16
From: Mansfield Texas
pcolt94, you are brilliant, it all mounted up flush this time around, if I was off it was only by a spline. It fired right up, being it is a new motor I shut her off and put the water pump and everything else back together and it now fires at will broke her in for 20 minutes at various RPM's, should run like a champ, CNC heads and Comp custom cam with a fresh bottom end, expecting 370 RWHP. Thanks again, I appreciate your timely and expert remarks.
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Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
pcolt94, you are brilliant, it all mounted up flush this time around, if I was off it was only by a spline. It fired right up, being it is a new motor I shut her off and put the water pump and everything else back together and it now fires at will broke her in for 20 minutes at various RPM's, should run like a champ, CNC heads and Comp custom cam with a fresh bottom end, expecting 370 RWHP. Thanks again, I appreciate your timely and expert remarks.
Not real brilliance, just a little experience and knowledge.
Best of luck with your new engine, have fun with it.
