Any Vw/Audi experts on here, got a 1.9tdi with boost problems

[Jamie.T]

Hi guys, wondering if anyone can help me.

Got a 2004 plate VW Touran 1.9tdi 105 with intermittent boost problems.

I know that they have a common fault of sticking veins in the turbo, but the actuator and operating arm is all moving freely and showing no signs of stiffness.

Fault codes came up with boost pressure sensor and intake air temp sensor which is the same unit. Ive replaced this unit and the turbo is now boosting a lot more often than it was, but 50% of the time ill start up and drive away and no turbo boost at all.

Ive also unplugged the MAF which made no change at all, could this be a sign of a fault?

Any help would be appreciated.

[mattr]

If disconnecting the MAF makes no odds, its could well be that thats causing the issue, its possibly knackered, or dirty, try cleaning it (IIRC brake cleaner works). Failing that have you checked all the hoses and the EGR, that can get gummed up. Might need to do a VW forum to find out where it is and how to get into it.......

[Jamie.T]

Thanks for that, i gave the MAF a spray with carb cleaner last night, but it also made no difference. Also the EGR is approx 1 year old and still looks like new.

I always thought that if you disconnected the MAF and it made no difference that it was ok, but if it made the car better then clearly it was at fault, not sure if im correct tho.

Will also be checking all the vacumn hoses later on as ive read on a few forums that is common.

[Chequered Flag Racing]

I use http://www.vwaudiforum.co.uk/

[super__dan]

Originally Posted by thomj316

I always thought that if you disconnected the MAF and it made no difference that it was ok, but if it made the car better then clearly it was at fault, not sure if im correct tho.

That's also mys understanding (on pugs anyway) as it defaults to a 'limp mode' that ignores the missing sensor and uses a basic map which will drive OK but not be optimised.

[mattr]

Yes, will depend on what the strategy is for a missing/incorrect MAF signal. But it sounds like you've covered all/most of the intake issues.
I have no idea beyond that

[andyroooo]

Silly question but did you clear the codes after you read them and replaced the sensor?