i just got this 88 IROC, rebuilt engine(read the sig) and rebuilt trans, now when i floor it from a dead stop the thing flies, but as the RPMs reach 3000-3500 it feels like a limiter kicks in and it doesnt shift until i come off the gas. my question is why would it do this? should i disable the VSS switch, or does he car need to be checked for an off firing cylinder?, a leaky vaccum/hose, or could it be that the engine is running to lean at higher RPMs or opposite, cause i am totaly lost here, thanks for any help.

 

I dont know much other than it really shouldnt be a misfire...or off-firing cylinder as you call it, because that would create problems thruout the powerband.

If I were you, I'd do a compression test anyhow. Check your plugs for any kind of fouling, deposits, damage. EDIT: When you complete your compression test, there should be no more than a 15% difference between the cylinder with the highest compression and that with the lowest compression reading.

1 more thing, invest in a prom reader.....run you about 100 bones give or take, but well worth it. I've used it many many times, very useful.

Your problem could be caused by more than one thing, faulty sensor, rich/lean. The reader will categorize the errors for you, and some sites list possible solutions to rid yourself of the codes.

gl

-blain