Boost Fluctuations

[Strick]

Hey guys,

Just recently bought an R34 gtr and have been noticing that when the engine is cold boost pressure is around the 1 - 1.1 bar (thereabouts). After the engine warms to normal operating temperature boost pressure on throttle only rises to between .6 - .7 bar. The only mod the car has is a Japanese exhaust system after the cat and the rest is stock. Any info on what could be causing this would be greatly appreciated

[Ben C34]

That's odd. It's also weird you thrash a cold engine to max boost. I wouldn't know how much boost my car makes when it's cold, because I don't want to kill it.

[Strick]

Of course I don't thrash the engine when its cold. The boost pressure rises as normal when the engine is cold but once the engine is warm it will only rise and the fluctuate at the .6 bar

[Got a Pulsar]

Boost leak that expands when warm?

[niZmO_Man]

As above, a wastegate line(s) has a hole somewhere?

Also, I don't rev my car beyond 3,000rpm when it's cold, so you must be thrashing it :P

[Got a Pulsar]

max 3000 rpm til warm.

agreed.

[tranman]

Check boost actuator and lines going to the actuator.