Boost Issues

[R32GTS4NZ]

Hi guys i have an rb26 and currently it has stopped making it's maximum boost. At wastegate pressure its only making about 5psi istead of about 7.5 at 10psi only making about 8 and 12.2 only making about 10psi also the boost is comming on late, any ideas of what the problem could be?

Other than this car appears to run fine.

Using a hks electronic boost controller and factory ecu. Wastegates have adjustable threads on them.

[R32GTS4NZ]

Have used searches and haven't been able to find the issue

[R32GTS4NZ]

Hi guys since last week have replaced blow off valve, intercooler hose clamps checked over everytrhing to make sure a hose hasn't come off. Pulled of the dump pipes to check turbo play etc and make sure the exhaust wheels were still intact and i still have the problem! using a manual bleed valve was able to get the boost gauge to read 12-13psi Anyone have any ideas on where to check next? Cheers

Edited April 11, 2010 by R32GTS4NZ

[blind_elk]

At wastegate pressure its only making about 5psi istead of about 7.5

It's either making 5psi or it's making 7.5 psi - which is it? Please clarify.

[Guilt-Toy]

clean the air filters and afm's to start with

[R32GTS4NZ]

It's either making 5psi or it's making 7.5 psi - which is it? Please clarify.

Apologies. At wastegate pressure it is meant to be making 7.5psi, with the boost controller low boost is meant to be making 10psi and high is about 12.2psi but is instead now making just over 5psi , about 8 and about 10psi on each respectively

clean the air filters and afm's to start with

I have cleaned the air flow meters using electrical contact cleaner. But not the air filters Could this be the cause of not building enough boost?

[FrangaR33]

Dodgy boost gauge perhaps? It may be making the right boost, you might not know it though

[R32GTS4NZ]

Dodgy boost gauge perhaps? It may be making the right boost, you might not know it though

haven't eliminated this option yet but it would seem odd the boost gauge would suddenly fail. Car definately feels slower

[R31Nismoid]

How do you know it's meant to be making 7psi @ the gate though?

There is no way to tell this from adjustable actuators. You have to measure it by a gauge when you make adjustments

[R32GTS4NZ]

How do you know it's meant to be making 7psi @ the gate though?

There is no way to tell this from adjustable actuators. You have to measure it by a gauge when you make adjustments

Sorry didn't mention. That is what it was running, It was all tested on dyno and I could measure boost off my gauge. Only recently has it started doing this, I have not made any other adjustments.

My boost controller has been locked (HKS evc4) and i can now only run wastegate, low or high boost (7.5,10 and 12.2psi respectively) however now am only getting just over 5 about 8-9 and just over 10psi

[R31Nismoid]

Ah ok well if things have changed then that makes it a bit different - i thought this was all being setup now.

So did it just "drop" overnight, or did you change/touch something?

Where is youe boost gauge taking the reading from? Turbo outlet or the top end near the T/B? (usually the TB, but ive gotta ask)

[R32GTS4NZ]

Nothing that i know of has changed only thing may have been a leaky bov but have a brand new hks one now. engine has only been in car few thousand kms but did about 1500 trouble free until this started. Its coneccted to a vacuum nipple at the rear of the plenum on top.