Ok so I have an 88 iroc z, brand new 350, has a mild cam, and It has about 500 miles on it, I changed my transmission and now it idles kinda rough, and makes a loud popping sound when I give it gas, might be backfire possibly because it comes from the intake on the tpi, it did run and idle fine before the transmission change, maybe timing issues? I'm not sure haha help!

 

Maybe the ignition wires are burned near the exhaust manifolds.
Check the fuel pressure, was the injectors replaced (305 orignanally?).
Its possible that the dist. cap got cracked while tilting the engine to get to the tranny bolts.

 

I found the problem, cracked distributor cap! thanks for the help, gonna change it out next weekend and let you know the results

 

Thats great!

 

Changed plugs, wires, dist. cap, rotor, and its still idling rough and backfiring

 

What is your base timing set to with the est disconnected ? Was your car a 350 before or 305 ? And if it was a 305 did you have the memcal reprogramed or replace and get larger 22#hr injectors ?

 

I honestly have no clue about any of that, I got the car from a friend, it was originally a 305 but he said he swapped everything over to make it work for the 350, it ran great before the trans swap, I'm gonna pick up a timing gun today, not too sure how use it but its a great day to learn haha, after I check it ill post results. how do I check fuel pressure? anything special that I need?

 

There is a Schrader valve on the rh rear part of the fuel rail. Hook a fuel pressure gauge there. The Injector should have numbers on them to identify them same thing with the memcal in the ecm. You can post pictures and numbers here and I will try to identify them for you.