Ok this ls1 conversion in 87 chevy truck. Truck was running for about week. My questions are is there any ways vats can reappear in pcm after being removed. Truck kinda backfired while running and now wont start. When I attempt to start it seems to back fire from intake? Any info please

 

When engine,harness pcm, were purchased. I was told from the guy the pcm was tuned and vats were removed.

 

Backfire sounds like some coil connections are wrong or your CAS was dieing and is now dead.

 

what you mean by cas?

 

Crank Angle Sensor. Common problem.

 

i'd vote crank sensor, its right above the starter. Check and make sure none of the wires burned against the header/manifold.

 

ok i will ck that!! thanks