fluctuating boost

T

Tango

Sunday Drivers
Hi There.

first off the car is a 99 classic uk turbo, only mods are itg panel filter and a rear section exhaust. so i have no gauges, the cat is still in etc.

what the boost appears to be doing is coming in at 2500rpm, backing off, coming in at 3500rpm, backing off coming in at 4500/5000 rpm again. as the car is new to me im not going to take it to 7k rpm just yet, want to get a few miles on it before i abuse it!

its not violent, just a subtle variation in the acceleration.

the car idles fine, and has been very good on juice.

i'm thinking an issue with the standard DV, as sometimes when i close the throttle i hear compressor stall instead of the regular recirc DV noise.
or is it a solenoid issue?

help appreciated i just want to enjoy the car without fear of breaking it!
 
[quote author=BazGF8 link=topic=40382.msg460361#msg460361 date=1389745336]
Problem is boost control , is the car remapped
[/quote]

standard map.

what would that point towards, too little preload on the actuator?
 
could be a waste gate problem, this happened my legacy TT , it was diagnosed as a wastegate problem, but turned out the gasket around the blow off valve was leaking air slightly, this was causing the boost to raise to high , too fast, then the wastegate was kicking in and releasing the boost, then the boost was raising too high again, it wasnt violent, it was a very smooth transition, but you could hear the wastegate opening each time, does this sound like it could be the issue??
 
that does sound like a similar issue, the boost does feel to be slightly peaky and then holding back. only got the car on saturday, hopefully i'll get a chance to have a poke around the hoses/mating surfaces tomorrow before work. the car is unmessed with, so i'm less afraid of their being something done incorrectly, more likely a worn part failing, like a gasket.
 
after a bit of poking around i think i have found the issue, there is a small tear in the intake pipe at the mouth of the turbo, my guess is as the turbo spools the draw of unmetered air increases, messing up the AFR. new hose will hopefully sort the issue. she wont be driven till its sorted.
 
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