I have a 95z that I bought with a knocking engine. I bought a 93 engine from a buddy with 40k on it. So I used the 93 bottom end, opti and heads ect, and the 95 manifold/injectors ect, and put it in the car. My question, is the tune with the 95 opti vs 93 opti different? It runs perfectly smooth until it warms up then seems like it loads up and kinda has some back fire noise or crackling like there is unburnt fuel. I also tried swaping it out with another 94 and under opti that I knew was not bad, still does the exact same thing. Just seeing if anyone has any ideas, also no codes being thrown. Thank you, Paul.

Also tried a different coil and icm.

 

Using the earlier long block should not necessitate any change in tuning. It's virtually the same.

 

Thanks, thats what I figured. Well now another question, when the car is cold it starts right up, revs nice and sounds great. After about a minute or so of idling or driving, it begins to chug and run very rought, and then dies. It barely starts back up, but if you let it sit for a few hours go out and try to start it again it starts right up and repeats. Just wondering if anyone else has had the same type of problem, Thanks, Paul.