JDM 2.0 GT Boost Problem

[Katfish]

I have been having for a little while now with a problem with my boost.

This is what happens I can not boost past 1bar, as soon as I hit one bar the car judders like mad and the boost flickers between 0.98bar to 1.02 bar and just keeps doing it even if I keep my foot down.

My air fuel gauge during this if going from rich to lean rich to lean etc

Happens both in prime and secondary.

I have changed coil packs & Prime Solenoid.

Next on my list is Fuel pump and filter.

Is there anything else that could cause this?

[Bookem]

I'm guessing it ran without the issues before? How recent has the issue came to be? What year and ecu, and is it tuned/chipped?

[Katfish]

Yes it was all good and the problem started around 2 months ago

The car is a 1995 with a 7C ecu which I have changed like for like to solve the problem made no difference.

[Bookem]

How about bov, is that stock? That could be leaking some, I'd post this over on Nasioc in the pre-2002 turbo forum.

[Katfish]

yes bov is stock.

I have some other problems with the car which may or may not be related

The engine rev hangs for about 10 secs when coming to a stop
Cold start is a problem when start car the revs are around 1400rom and drop slowly over 5 mins but when It drop is drops below 500rpm and idles there if I adjust the idle control valve to say 700rpm its all good till I turn off the car and it goes back to under 500rpm.

But when the car is warm say after 20mins driving the car idles great 650-700rpm

as said dont know if this is related

[Huffer]

I don't think you're adjusting the IACV, I think you're messing with the Throttle position sensor - which is self learning depending on vaccum changes.

Sounds to me like you have a vaccum leak around the TPS, and the car has put itself into some kind of limp mode to compensate.

[Cervantes]

what is the max rpm youre getting?