2000 LaSabre not start when hot

[razzbarry]

My LaSabre does not start when the engine is hot. I drove it 120 miles and it ran great, no apparent problems. It was about 70 degrees outside. Immediately after I turned it off I tried to start it a couple of times and it started fine each. However, 30 minutes later I tried again and it would not start. The engine would crank and it sounded like it wanted to start but it also sounded like it was knocking. I tried it after another hour and it started. right up. I had a similar trouble on another LaSabre and it was the crank sensor. But that car would not start right after it was turned off but would start after about 30 mites. That was the crank sensor.

It seems that after something in the engine compartment has time to hat up it doesn't work correctly once it gets hot. I assumed that the crank sensor was not the problem because it is bolted to the block and should have been as hot as the block. Something else needed time to get hot with no air running into the engine compartment after I turned the engine off.

What could cause it not to start when hot but would take time to heat up once turned off?

I connected an OBD2 reader to the port after it finally started but there are no error codes. Would a crank sensor failure generate a code? Would the ignition control module generate a code if it failed. It is weird that nothing is generating codes if the engine won't start.

How can I eliminate the different components that are hot sensitive. It would probably be cheaper to just replace the parts until the problem goes away rather than take it to a repair shop. That is if I can find a logical order to replace the parts. Any ideas on how to proceed?

Thanks

 

[IMSITINGINYOURCHAIR]

Sounds like a failing ICM. when those go they tend to go in the summer.

 

[gnhbodyguy]

To test the ICM, take it off when the car won't start. Put it in refrigerator for 10 minutes or so. Install it and see if it starts.
If it does it could be the ICM.

 

[jcc3inc]

Sir:

I have had (2) crank position failures in 3800's. One quit running when the engine was hot, and the other refused to restart after being shut off hot for a few minutes. BOTH restarted after they sat for a while, and replacing the crank sensor solved both problems. My engines were 97 LeSabre ans 91 Reatta. Both were around 100,000 miles.

JCC