Hey up lads (and lasses).
Over the past week my 1998 uk turbo has been overboosting at nearly 1.5 bar (indicated by my boost gauge), and in doing so the 'Fuel Cut' has kicked in and backs everything off till i let off throttle. Does anyone know why its now boosting to 1.5 bar instead of the usual 1.0 bar indicated on boost gauge, and how to cure it.
Only mods to car are panel filter,full de cat,dump valve,STI intercooler and Samco hose.Have had these for ages and never no probs.

Cheers in advance.

Oggy

 

It could be new clutch time, as mine started overboosting when mine was on it's way out.

 

Just had new clutch fitted last weekend cocker and was doing it a day or 2 before and still doing it now.

 

mines did the same turned out to be a sticking dump valve, strip down and regrease with castrol lm grease worked a treat back to 1.2

 

1.5bar?? I thought the fuel cut was lower than that for UK cars, about 1.2???

Ns04

 

Fuel cut is way lower than 1.5bar! 1.27 rings bells but don't quote me.

Also, 1.5 bar is really dangerous territory on a TDO4 - you don't want to let it do that too often. I overboosted to that once very briefly on my MY99 and absolutely bricked it!

 

if teh car doesn't feel any different and its not hitting boost cut then bet you've got a duff gauge.

 

Clean out the small vacum pipe that connects between the turbo and the actuator. there is also a t-piece inserted in this pipe that runs to the boost control solenoid. clean that out as well. best to use carb or brake cleaner spray (Not WD40)

It could be that the pipe is partially blocked with oil as there is a small brass restrictor in the hose between the turbo and t-piece. If this is reduced in size by oil/fod boost will increase.

 

stuck waste gate actuator arm?

 

Cheers lads.
I'l clean out vacuum pipe as mentioned and check others
for splits while i'm at it. Changed the dump valve earlier in
the week cos thought that might cure it but dint.

 

I'm sure i had this once on a MY99.

two weeks later, before I had a chance to take it to PE i melted a piston.

Turned out to be a dirty MAF sensor.

DON'T mess about trying to fix it your self, take it to an expert.

Mine cost me a lot of cash (£2k+) because i didn't act quick enough.


Go on:

Pay someone who knows

 

Maf failure has crossed my mind but thought it was really only an issue on
my99 models. Also wondering even the the Check Engine Light hasn't come on wether there'd be and fault codes to possibly diagnose,and if so how do i find out the reset ecu?

 

MAF failure is an issue with all of them - usually in conjuction with an induction kit. However 99-00 MAFs are particularly feeble. So thats why you hear about MY99s alot

Cheers
Steve

 

have you changed the oil lately