1997 z28 6 speed (not the one in sig)

when i turn the key off it will run on doing that sputtering thing fro about 1-3 seconds depending how long it was run for.

timing is my guess but i though all that was done electrically

also has lag during acceleration but when held at a constant rpm it runs fine

need help

 

Timing has nothing to do with when the key is off. Sounds like you have a couple of issues. Probably a large build up of carbon and the throttle plate is probably adjusted open too far to compensate for a poor idle.

This is the only stuff to put in the engine.


Only available at dealers.

 

I know on one of my other vechiles i had run on I believed caused by high compression and hot cylinder temps...but that is prolly a bit different

 

Although I agree with speedy. I feel that it is probably a leaky injector. Reason being is nothing will happen without sufficient fuel and air. You can get plenty of air through the tb at stock setting to fire a single cylinder a couple of times. But it can also be from poorly adjusted throttle blades. Carbon and too hot of a spark plug will do it also.