Unstable boost

[Gonza]

Evening all,

Done lots of reading now and none the wiser so thought I would give this a go...

Fairly recently had a few tweaks on the car (02 WRX)

VF35
STi pinks
Ported headers
De cat up pipe
Sports cat downpipe
Fuel pump etc
ECUTEK

In 3rd gear, 4th and 5th, when half throttle the boost fluctuates between 10 psi and 19psi from about 3.5k right up to 6k. However, it will not do this if full throttle, only half?? Its like it spools, then gets pulled back etc etc. Even if I stay half throttle and it fluctuates, if I plant my foot full throttle during the fluctuating boost it will rise up to 18/19 and stay there...??

I've read plenty about pipes etc, and have pressure tested all small pipes around the turbo, boost control solenoid etc. No leaks, splits etc. Have also cleaned the BCS. All clamps are tight etc, dump valve holding fine too.

I'm running out of options now and not sure if anyone else had anything similar? During mapping the duty was pulled back a touch as the temps were getting up due to my standard I/C, so will be looking out for an STi one soon to make the most out of the mods, but would like to sort this first.

Any help would be great...

Many thanks,

Rich

[Scott.T]

Mention it or take it back to your mapper quite simple to fix as long as you can find a stretch of road where it can be repeated.
It's got too much boost duty or too little boost target for part throttle.
Car is trying and is capable of boosting but goes too high so ECU pulls it back because it breaches the set target boost.
It then tries again hence the oscillation.

Quite a common fault after mapping, more so for Rolling Road mapping as they don't often run it at a part throttle scenario or even use a generic map and just tweak the full throttle settings.

There are quite a number of similar questions where people experience this on the long motorway drive home from wherever they got it mapped.

[Gonza]

Thanks for the response, I'll have a chat. Have to admit it's been pretty much since day one, but thought it may be mechanical so would try and look at it myself to save hassling the guy.

Will give him a call I think.

Thanks again.

[Gonza]

Problem solved!!!

Turned out that the turbo was spooling quicker than what the rest of the set-up was ready for, so had to be reigned in a touch (I hope that's the clearest explanation).

Scott, spot on!!

Thanks to all who responded...