I just swapped a T5 into my car and did intake gaskets, did the timing got it timed just above 6* runs pretty good, but still a little hesitation and a little misfire under load in 3rd gear, also it idles high until warmed up. WOULD me buying a new ECM for a manuel trans car help? since my computer still thinks its an automatic? ANY ideas or help would be greatly appreciated

 

your computer should not be thinking its an automatic if you have the VSS hooked up. i just did the swap myself and everything is fine since i left the engine alone, minus the fact that 5th gear is outta wack.

 

I agree. It's not the ECM. My opinion is that you need to diagnose the problem that is causing a miss in 3rd gear, high idle, and hesitation -sounds like a possible vacuum leak so far. Under those conditions, the ECM should really "care" if it's an auto or not.

 

Are you guys absolutely sure? because ive had a friend with an 89 tpi trans am and he had the same problem where idle isnt dropping to normal till after the car is stopped he thought it was computer too. which vacuum lines should i check? all of them are connected or patched for the most part and the timing is perfectly 6*. any chance the o2 sensor is going bad and the incorrect amount of fuel is being sent to the throttle body?

 

well, to tell the truth, with out me actually self diagnosing it, i cant tell you the problem. mine sometimes runs a little high, sometimes a little low. she is temper mental. my idle is typically 550 RPMs, but i have seen up to 1150 RPMs in between shifts, but if i let it out in neutral for 3 seconds, it drops back down to 550. but if yours is constantly going crazy, its not the timing, and its not the fuel. almost every car has its gremlins.

I would make sure all the hoses are connected to the TBI or TPI system. If there is a leak, you should hear a distinct hissing sound when you rev it up to 2500 or 3500. any higher than that you are not going to hear it.

also check the spark plugs if its misfiring. i had a 79 camaro and the spark plug wire had melted to the headers, so it some times grounded, causing a build up of fuel in the cc. then it would later spark when i floored it, causing a loud misfire and the car would shutoff for a second.

the whole high idle thing, i sometimes just turn on the A/C or heat on low, and watch those RPMs sink.

but you should check all ignition wires for sure as well as all vacuum hoses. and is yours tpi or tbi?