ImportCorner

1991 240sx s13 blacktop

it runs good sounds good, but when it hit 3000 rpm it doesnt want to move out of its own way

i checked all the couplers and there are tight
i checked all the vaccum lines and tight with no leaks

any idea what the hell could be wrong?

JimmyHat

Can you rev the motor to redline? Is the timing set correctly?

TJElite

I'm no expert, but I'd lay odds on a boost leak somewhere. Just because your couplers are tight, doesn't mean you aren't leaking.

Modified mag had a piece on pressure testing the system with a compressor. Basically, you just have to block off the turbo inlet, and put about 15 psi on the pipes.

ImportCorner

i will try that thnks but it could be leaking that bad to run like a sohc neon at 3000 and up?

ImportCorner

yes i can rev to redline and timing is correct

TJElite

When the boost leaks out, the car will run rich, since the air has already been metered by the mass air. It would rev in neutral, because there is little or no boost. Boost should be starting to come on about 3k, so that makes sense.

A guy I know had the exact same problem, and it ended up being the bolts that hold the outlet pipe to the stock turbo. Or rather, the lack of bolts that were supposed to hold the pipe to the turbo.

ImportCorner

thnks make sense i will try that

Mr Takara

well check boost leak...then after that check connections to maf, etc...also check plugs and gap them right...could be alot of things..but its prolly simple

ImportCorner

what should the right gap be for plugs?

Epstein

The accepted "correct" gap is 0.028".

You problem sounds exactly like a boost leak. 3000rpms is about when the turbo starts to get moving, exploiting any leaks in your charge pipes. If you can rev higher under light throttle, then this is definitely the problem.