Test Turbo -- Limited boost

[mark_sarah]

Can anyone help me with the best way to test my turbo?

Its a 1999 A3 1.8T sport with 150010 miles on the clock.

My boost is limited to 3.5psi. I have replaced my MAF sensor, and tested my N75, so i know they are not the problem.

I have used Vag com, but no faults were listed.

There is no distinctive colouring coming from the exhaust, however i have just noticed the turbo is wet with oil.
Would that suggest a seal has gone? And would that restrict/stop the boost?

I have seen on here in the past, it is possible to purchase a turbo core, to replace the damaged bearings and seals. Is this an easy fix? And where would i purchase this from?

Cheers in advanced.....

 

[Welly]

If the turbo is cream crackered then a seal kit is possible.

See here:

http://cgi.ebay.co.uk/KKK-K03-K04-T...arParts_SM?hash=item4a9eb50749#ht_2269wt_1165

 

[mark_sarah]

So there is no way of testing the turbo?

 

[badger5]

if you disconnect the pipe to the actuator so it does'nt and cant open, and take a veyr carefull drive and ease onto the throttle and seeif you get more boost (it is uncontrolled boost like this) then it will confirm if the turbo itself can deliver more.. if it cant its faulty. if it can, check for n75 valve being connected electrically, no broken wires, plumbing to and from it is ok etc etc etc


REMEMBER, CAREFULL ON THE THROTTLE WHEN TESTING.. if turbo does work its uncontrolled boost so dont drive it like this, just see if it can spool up more, then refit the pipe

 

[mark_sarah]

With pipe disconnected it boosts to 15psi which is about right. I know the N75 valve works fine, so i have no idea what to try next.

Thanks for your help with the Turbo test..

 

[Welly]

Yeah, that is about spot on from a K03 turbo boosting against a large port head.

Sounds like it may be limp mode related? The N75 valve may work spot on, but if the ECU is putting the car into limp mode the N75 valve will remain open, meaning you only get actuator pressure.

 

[mark_sarah]

How do i get it out if limp mode..?

 

[badger5]

only 15psi? what rpm does it spool that boost?

 

[Welly]

only 15psi?

That was all my AGU would make with a K03 IIRC....

 

[badger5]

it shoudl spike more than fall away to that sort of level.. and where it starts to spool this pressure is significant.
i have had agu's with shagged turbos which spool slow like a bt, and dont make much boost... worn out

 

[mark_sarah]

Problem solved.. It was a leaking injector seal.

Cheers for all the help..

 

[Welly]

Problem solved.. It was a leaking injector seal.

Cheers for all the help..

Thats a new one! LOL. Good find!!