92 eagle talon turbo question

i am looking at a 92 eagle talon tsi. it runs very rich, emitting a black puff of smoke when i shift it and leaving the bumper black above the exhaust. it has a 16g turbo on it that was taken off from an eclipse. it also has a non stock exhaust, although im not sure what it is. at about 4000rpm's, the engine stutters. however, when the wastegate on the turbo is wired wide open the whole time, it doesnt do this until 6000rpm's and it runs a lot better. i was told that it does this because of the larger turbo and the more powerful exhuast giving more power to the engine than the computer wants. i dont believe this however, because it doesnt explain why it runs rich. the timing belt and valves were just recently changed. any help would be appreciated. thanx.

anyone?

I am going to copy this to the forced induction forum to see if that helps.

ok since you changed a lot in the engine i would say those are the problems that i can see resulting in black smoke

ecu overcompensating

bad valve timing and you have a lot of overlap.

maybe the ingnition is too retarted

Maybe he just needs a tuneup so his engine doesnt stutter, like you know, spark plugs wires etc... and the running rich my car did that too , the bumper was gettin smoke reidue on it, the only thing i can suggest is a catalytic converter?

if by studdering, u mean FUEL CUT, i wouldnt bother with the car. its annoying and u will hate driving it. u can fix it with some work, but i'd keep looking around if i was u. also, with the TDO5H-16g on there (big or small whatever u have), its not gonna hit its full performance with minimal mods. u'd work out ur piping (preferably 3" all the way through, complete a few free modifications and maybe clip some of the blades on the wheel to reduce turbo lag). i'm a little curious about the timing belt and VALVES being changed recently, kinda sounds like the timing belt snapped, did some damage to the valves, may have damaged more, but the owner just replaced the valves to have it run and is trying to sell it. i'd run a carfax and see what u find, but do not by that car without getting some more information.