LT1 problems. No start.
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Joined: May 2014
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From: Dallas, Texas.
LT1 problems. No start. Hey guys! I'm new to the forums and i am hoping you guys could help me out. I have a 1993 Trans Am with the LT1. I drove it 200 miles home and all was fine. I pull in to a gas station,put some gas in the thing and IT WONT START. It cranks but does not turn on. Starter,battery,alt are all fine apparently. I even thought it was a fuel problem since it started right up with starter fluid (at first). Had to ditch the car and come back 5 hours later and it starts back up. Checked pump at 41psi. My mechanic ordered a new computer and said/thinks that it is the problem... Don't know about that. Any input guys?
Tags; camaro z28 ls1 lt1 trans am no start angry
Tags; camaro z28 ls1 lt1 trans am no start angry
More than likely your ICM (ignition control module) is faulty. When it gets hot it has an open circuit. Its located on the pass. side head,above the coil. Local auto parts can test it. Find another mechanic.
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replacing the PCM is WAY down on the list...if it is even on it for no start problem.
ICM is a "likely" suspect. they often "test" OK as they are not hot....heat affects them which is why there is heat sink paste between them and head/mounting block.
coil
opti
opti wire harness
all are WAY more likely than PCM
was the 41PSI on FP with or without vacuum?
ICM is a "likely" suspect. they often "test" OK as they are not hot....heat affects them which is why there is heat sink paste between them and head/mounting block.
coil
opti
opti wire harness
all are WAY more likely than PCM
was the 41PSI on FP with or without vacuum?
TECH Apprentice
Joined: Jun 2012
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From: Mississauga Ontario Canada
id say icm, sounds heat related. try the icm cooling mod, its free and easy check it out on shbox's website
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From: Dallas, Texas.
You guys are badass. I was thinking ICM. I'm pissed that he didn't even test the ICM. I mentioned it only 6,000 times. Now I have to wait until the new computer gets back and he "figures out" that wasn't the problem. I'm taking it to another mechanic or replacing it myself. Any chance it could be the PCM? Also how hard is the ICM to replace?
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Icm is really not that bad to replace. When you open your hood you should see on the lower right side of the block your coil. Basically i think it's unscrewing a few bolts and drilling out a rivet or two if your replacing the coil as well. But it's should only take less then half an hour.
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From: Dallas, Texas.
When I get the car back I'll check it out and take a look at it. hopefully I figure this out. I got this car a week ago and I haven't even been able to fully enjoy it because its been in the shop.. Haha. Any other possibilities besides ICM? Would spraying Freeze Spray on the ICM help diagnose it!
Staging Lane
Joined: Dec 2013
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Are you getting any spark from off the coil? If you are but your not getting any spark at the plugs the rotor side of the opti has failed. If your not getting any spark at the coil, hook a noid light up to one of your injectors and see if the light flashes. If it flashes that means your optical sensor on your opti is working and again it would mean its something between your coil to the plugs and since you've done plugs and wires that would probably mean its the coil. Have you checked the VATS?
Thread Starter
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From: Dallas, Texas.
Thats exactly what is going on. No spark to plugs. I bought a new rotor for it and they are putting it in today or tommorow. The original opti is in there hence making it 21 years old lol. Hopefully that fixes it. This has been a nightmare.
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I am at my wits end with this hunk of junk. I have replaced the coil,new optispark,rebuilt computer, icm , spark plugs,wires,knock sensor,coolant temp sensor. Still just turns and wont start... i am getting pulse to the injectors with the new opti but no spark to plugs. ANY input would be great
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From: Dallas, Texas.
Did your Formula do the exact same thing? I took it to a new shop and the guy is a lot more knowledgable. He fixed my wiring to the coil. The last shop had two solid colors wired from the coil to two STRIPED wires. It made things worse and drained my battery. I was furious. Apparently he says it is the Opti,my ecm rebuild was crap,or that the two shorted wires fried my ecm. Whatever it is, it is not letting my car get spark to the plugs. This is my first V8 fbody. My other two were 3800 sixxers.
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From: Dallas, Texas.