lt1 HELP!

[NjbadSS]

I am looking for advice from anyone with knowledge of LT1 vehicles. A little about the car, it is a 96 trans am, lt1 engine, 6 speed manual trans. It has about 129k miles, brand new gm crate engine with about 6k on it now since installed in the car. The car starts right up with no problems, idles smooth but after driving the car a short distance until it warms up, it simply stalls out and will not start back up. We put a new computer in the car, opti spark, ignition module, fuel pump, but the problem continues. Does anyone have any other ideas what this might be? We have had several mechanics look it over and can't figure the problem out. It is a nice car with a new engine and transmission, we would hate to sell it because of an issue that may be simple to fix.

[sweetbmxrider]

No codes?

[Blackbirdws6]

I am looking for advice from anyone with knowledge of LT1 vehicles. A little about the car, it is a 96 trans am, lt1 engine, 6 speed manual trans. It has about 129k miles, brand new gm crate engine with about 6k on it now since installed in the car. The car starts right up with no problems, idles smooth but after driving the car a short distance until it warms up, it simply stalls out and will not start back up. We put a new computer in the car, opti spark, ignition module, fuel pump, but the problem continues. Does anyone have any other ideas what this might be? We have had several mechanics look it over and can't figure the problem out. It is a nice car with a new engine and transmission, we would hate to sell it because of an issue that may be simple to fix.

Does it start up after it cools down? If so, I had a very similar issue and replacing the ICM solved the problem. I also did the spacer mod to move the ICM/Coil unit off of the cylinder head. It sounds like you replaced the ICM already but did you also check the coil?

I would be driving down the road like nothing is wrong and the car would just stall. It would take a little bit to cool before it would fire back up. Sometimes, no issues and other times, it would stall within 10 min of driving.

Any other symptoms?

[omarcamaro]

Sounds like a coil I just had that same problem with mine

[NjbadSS]

Thanks for the help guys. A little more information. The car does not throw codes, which is another reason this is so difficult to figure out. Exactly what you said blackbird, car runs great until it warms up then doesn't spit sputter nothing, simply stalls. After letting it sit, it does start back up and you can drive it but the identical problem occurs. The icm was the last thing we switched along with the ignition inside of the car, also got a brand new key thinking maybe the sensor on the key wore out. The coil you speak of has not been been changed though. Before switching that for a new one, is there a way of testing the current one to see if it is good?

[LTb1ow]

Thanks for the help guys. A little more information. The car does not throw codes, which is another reason this is so difficult to figure out. Exactly what you said blackbird, car runs great until it warms up then doesn't spit sputter nothing, simply stalls. After letting it sit, it does start back up and you can drive it but the identical problem occurs. The icm was the last thing we switched along with the ignition inside of the car, also got a brand new key thinking maybe the sensor on the key wore out. The coil you speak of has not been been changed though. Before switching that for a new one, is there a way of testing the current one to see if it is good?

You can test it, but the test does nothing if its not hot when tested.

[sweetbmxrider]

Yeah, when it stalls and doesn't restart, pull off the coil wire and see if it sparks against some metal. Did you use thermal electric grease when you installed the icm?

[NjbadSS]

Yeah, when it stalls and doesn't restart, pull off the coil wire and see if it sparks against some metal. Did you use thermal electric grease when you installed the icm?

I will try this next time I work on the car and see if I get spark when it stalls. When we put the icm in, we did use the grease which came with it from the parts store. I will keep yas updated in what I find out when I test the coil for spark

[Blackbirdws6]

Adam stole my coil and icm which were practically new. Otherwise you could have it to test.

[sweetbmxrider]

I still got em, pm me and cover shipping and its yours

[S.J.SLEEPER]

coil

[BlackBADaSS02]

Does it start up after it cools down? If so, I had a very similar issue and replacing the ICM solved the problem. I also did the spacer mod to move the ICM/Coil unit off of the cylinder head.

This is what I did. My ICM was bad, so I replaced it, but it wouldn't start up again while it was hot. The spacer mod seemed to work.

[spina74]

Coil...samething happened to gmkidd91 and it was the coil

[RamAir95TA]

Probably coil, but...

Did you have it SCANNED for codes, or is the SES light just not coming on? There are some codes that will not set the SES light.

Another possibility could be the temp sender in the water pump.

[Pampered-Z]

Just throwing some other ideas out:

When you say warms up? how long a time? we talking 1 minute or 10 minutes? Is it stalling while moving or when you stop / at idle?

Do you have acess to a fuel pressure gauge? If not when it stalls out check the shrader valve to see if you have fuel pressure. Could be the pump or maybe the screen collapsing, clogged filter.

Also suggest using a noid light to check for injector pulse signal.

Or are you sure it's spark related?