LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

LT1 missfire.

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Old Aug 1, 2008 | 11:28 PM
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LT1 missfire.

Well my 1995 camaro 383 le2 setup keeps breaking up after about 6300rpm the thing is it only does it when the car is hot, rev limiter is set at 7150, if i let it cool down it runs great. I been fighting this problem for about 3 months i have now replaced the pcm,iat,tps,map,maf,opti 2 times,Icm,plugs,wires, Any ideas?? Also if its really hot out it will shut off and not restart till it cools down..
Old Aug 1, 2008 | 11:55 PM
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Longshot here, but I'll give it a try. I'm going to guess that you have headers. If your wires are routed in the stock location, they may be getting too hot, even though no signs of burning may be showing on old wires. You could mount them over the valve covers and wrap or otherwise heat protect them with 1000* or better protection at the boot and where it is close to the header tubes. This could make sense because it only happens when hot, and I'm going to guess you're not getting any codes.

Possibly 02 sensors?
Old Aug 2, 2008 | 04:05 AM
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Do you have a cooler thermostat and a fan switch you can turn on and off when needed?
Old Aug 2, 2008 | 07:12 AM
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Originally Posted by MarcR94v6
Longshot here, but I'll give it a try. I'm going to guess that you have headers. If your wires are routed in the stock location, they may be getting too hot, even though no signs of burning may be showing on old wires. You could mount them over the valve covers and wrap or otherwise heat protect them with 1000* or better protection at the boot and where it is close to the header tubes. This could make sense because it only happens when hot, and I'm going to guess you're not getting any codes.

Possibly 02 sensors?
sorry i forgot it has new o2s also, no codes,last night i tired the icm spacer mod so far its working.
Old Aug 2, 2008 | 07:13 AM
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Originally Posted by mrmint69
Do you have a cooler thermostat and a fan switch you can turn on and off when needed?
yea car has a 160 T-stat and doesnt run hot at the most it will see is 195 maybe 200.
Old Aug 2, 2008 | 05:40 PM
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The icm spacer mod is a good idea. If it has a lot of miles on it, a replacement might be a good idea. Once the part starts to have problem from my experience it just a matter of time before it goes out. I payed about $40 for mine and it was well worth it since I didn't have to worry about it again.
Old Aug 3, 2008 | 07:18 AM
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ok go drive that car and let us know how the spacers work or not i this case.
Old Aug 3, 2008 | 11:27 AM
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well drove the car and it started acting up after about a hour of driving, so i then replaced the icm and drove the car for about 2 hours and no problems so i think its fixed ill let you guys no how it goes tomarrow.
Old Aug 3, 2008 | 02:52 PM
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cool. well anyways, after you spaced the icm out, it would take a couple hours of driving to act up? before it would act up as soon as the eng. got to operationg temp? is that accurate?
Old Aug 3, 2008 | 03:38 PM
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Originally Posted by IrocSS85
cool. well anyways, after you spaced the icm out, it would take a couple hours of driving to act up? before it would act up as soon as the eng. got to operationg temp? is that accurate?
before i spaced the icm it took about 30mins of driving to act up or so yea about operating temp, then after the spacer it took about a hour to act up then i replaced the icm and kept the spacer and everything seems fine.
Old Aug 6, 2008 | 01:56 PM
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well hte car is doing it again now with code 42 IC grounded..
Old Aug 6, 2008 | 02:43 PM
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How old is your coil?
Old Aug 6, 2008 | 05:52 PM
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Originally Posted by GMRL
How old is your coil?
3 weeks old
Old Aug 6, 2008 | 07:52 PM
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Be glad you're getting a code. There are who knows how many of us that have or are currently chasing misfires and are given no codes.

I'm going to try spacing the ICM myself now because of this thread.
Old Aug 7, 2008 | 12:34 AM
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appears to be electrical/ignition from what is being typed here but also make sure the rockers are ONLY 1/16 to 1/8 of a turn past zero lash or it can cause the engine to lay over or break up at high RPM.

Lloyd



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