I just replaced my Cat which was fried in hopes that that would solve my hesitation problem that starts around 2500-3000 rpm. The cat was melted indicating a lean mixture(the spark plugs grey/white color also verify this). Anyway, It helped a little, but the car is still hesitating.

The turbo starts to kick in really early, like around 1700-2,000 rpm and spools, but the car doesn't go really fast and then the turbo continues to stay spooled even at low speeds while not pushing hard at all. I have to back completely off the throttle to get the turbo to stop spooling; then give very light throttle so that the turbo doesn't spool up in order to accelerate. If the turbo spools then the car hesitates. Could this be my T25 going bad?

Help please!

bump

have you noticed a drop in VAC pressure at idle?

I don't know. How do you check this?

i guess you don't have a boost gauge. i know that you have an apexi AVC-R. doesn't it display boost? what does it read at idle? if it displays numbers in Hg this would be VAC. according to my mechanic, if your VAC pressure starts decreasing and stays that way your turbo is going bad.

Yea, I feel dumb. At idle the AVC-R reads -445 mm Hg. I think this has gone down over the past year, but I can't remember exactly what it was a year ago. Does this number sound low to anyone???

if the VAC has gone down considerably this could be a sign. :(

I took off the Distributor cap today and found that the cap electrodes and rotor are worn badly and coroded. This is good news to me, because it means that is probably my hesitation problem and its a cheap fix. I have never replaced the cap and rotor so this makes sense.

At idle, my nx has 20" of vacuum, which converted from your number in mm = 17.8" of vacuum (roughly). That number seems a little low to me. Could you possibly have a vacuum leak somewhere?

Doesn't this also depend on the AAC valve setting? Maybe I need to close that valve a bit.