SC lt1 shuts off after 20 mins of driving...Help?
03-13-2012, 09:14 PM
#1
SC lt1 shuts off after 20 mins of driving...Help? As the title says.. My procharged lt1 shuts off after 20 mins of driving. Im thinking its a ignition issue . Has anyone had a problem like this?? Im thinking it may be coil related ,because it sits on top of the blower and thats the hottest place in the engine bay.... But thats a guess... Help thanks
03-14-2012, 02:17 PM
#5
Yea another vote for ICM, my ICM just took a ****; causing random shut downs while driving 
No codes, nothing. Had it towed and my buddy/mechanic said it started right up....so he drives it home and what do your know...dies and he can't restart it. So two tows within two days because of that damn POS ICM....it's the 3rd one that's been replaced on my car too (over 14 yrs) I'm coming to appreciate the ignition system on my other LS1 car more and more everyday...AAA is a necessity if you own a LT1 lol 
No codes, nothing. Had it towed and my buddy/mechanic said it started right up....so he drives it home and what do your know...dies and he can't restart it. So two tows within two days because of that damn POS ICM....it's the 3rd one that's been replaced on my car too (over 14 yrs) I'm coming to appreciate the ignition system on my other LS1 car more and more everyday...AAA is a necessity if you own a LT1 lol 
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03-14-2012, 09:44 PM
#9
Thanks for all the help guys.... Im sure thats it. My ICM is the one that came on the car new. So i guess it lasted pretty good huh? I drove the car close to my house today for about 20 mins and it happend again. I just think its so weird that it runs perfect and then bam..... car shuts off...
03-22-2012, 09:56 PM
#10
I put a new ICM on the car and it didn't change a thing. The car is still dying. I also went out and rented a fuel Gage to check the fuel pressure and it was fine. The fuel pressure read around 44 PSI at idle. Is there anything else you guys could possibly think of, I'm completely stumped! I even checked the coil and it checked out fine. I have a 6a MSD box on the car. Do you think the MSD box could have gone bad?
03-22-2012, 11:33 PM
#11
Few weeks ago my car did that same thing. would drive perfectly no misses no sputtering it would just die after 15-20 minutes. checked fuel pressure, checked injector pulse, fuel passed. I replaced the coil, still had the problem. Took the icm to get it checked it passed several times. I even called a buddy of mine to try another icm and it still turned off. Finally took the opti off which I had my doubts it was the problem. I noticed I had a bad opti rotor. I can't garantee you this is your problem but I hope it helps. GL.
03-23-2012, 10:09 AM
#12
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Being supercharged was there a oil pressure switch added to the system? When the car shuts off, at that moment do u have fuel pressure? Mine would run fine loose fuel pressure and die, checked fuel press. And nothing had to bypass rela behind driver kick panel. Repace relay, gotta be fuel or spark!
03-23-2012, 11:55 AM
#13
Being supercharged was there a oil pressure switch added to the system? When the car shuts off, at that moment do u have fuel pressure? Mine would run fine loose fuel pressure and die, checked fuel press. And nothing had to bypass rela behind driver kick panel. Repace relay, gotta be fuel or spark!
03-23-2012, 01:30 PM
#15
How did you check out the coil? When my ICM took a dump it took the coil out with it too somehow...replacing it with a known good one fixed my issue. Anything is possible as far as your MSD box...murphy's law....I would disconnect it for troubleshooting purposes just to eliminate it as a potential cause.
03-23-2012, 06:48 PM
#16
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I know that our cars do not come with an oil pressure switch from the factory. But if it were me i may add such a switch to stay on the cautious side, it would cut the fuel off when u lose oil pressure.
03-24-2012, 10:12 AM
#17
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I'm having a similar problem. Car starts, runs fine then out of nowhere it shuts off and won't start again. This can happen at any time, but seems to only happen around idle RPM. I thought it was the ICM, replaced it and still no change. It may still be the ICM heating up (I need to get some heat-sink paste so heat transmits to the ICM heatsink properly). It feels like an electrical cut-off, especially spark, because everything else works. It's going to take some time for me to diagnose the problem and find the cause, too busy doing other things. If anyone comes up with a solution I'll be glad to hear it.
Last edited by Speedy; 03-24-2012 at 10:18 AM.
12-21-2012, 06:19 PM
#18
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My car (97z28) runs then u turn the key off and try to crank it back up and it gets no spark. I've replaced the icm and coil. No refire during the cool down period..
12-23-2012, 03:29 PM
#19
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Mine did this and it was the opti. It would run perfect until it didn't. No misfiring, nothing. Just would die then fire back up again eventually and ran like a champ
12-23-2012, 07:53 PM
#20
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My car was doing this also. It would run perfect then just die and wouldn't restart for 30+ minutes. I replaced a Chinese ICM with no paste with an American one with paste and did the spacer mod and haven't had a problem with it since.
