[s-cars] Low boost when engine is warm- please help!

[TM]

Calvin-
Thanks for the advice- I think it has come to the point where
I have to throw in the towel and give the car to my mechanic to
diagnose and fix- I don't have a 'scope and do not know enough about
how to use one in order to get any sort of meaninful info from one.

I have not checked the WGFV, although it does click when doing the
output tests via the 1552.

Taka

-----Original Message-----
From: calvinlc at earthlink.net [mailto:calvinlc at earthlink.net] 
Sent: Sunday, September 05, 2004 12:29 AM
To: TM; s-car-list at audifans.com
Subject: RE: [s-cars] Low boost when engine is warm- please help!


Taka,

With a hard problem like this I guess I would try to get ahold of a
portable oscilloscope or a multimeter that measures duty cycle and tap
into the wastegate control signal.  Compare the duty cycles when you are
cold and everything is working properly to when you are warm and boost
isn't getting up to full.  You could then isolate between a problem not
allowing the car to get to full boost mechanically or a problem with the
computer not commanding it to full boost.  If it is the computer then
check each and every sensor's signal with the O-scope while driving (two
person job preferably).  If it is not then I would start by swapping the
WGFV with a known good one.  Good Luck!

--Calvin



-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com]On Behalf Of TM
Sent: Saturday, September 04, 2004 12:32 PM
To: s-car-list at audifans.com
Subject: [s-cars] Low boost when engine is warm- please help!


Any further help on this problem?

Quick recap:
Car runs fine when cold, drops to 10 psi peak when warm, can see short
peaks above 10psi, but they quickly get throttled back. This ONLY
happens when the engine is warm- past the 2nd hash mark from full cold.

I replaced the multifunction temp sensor on the water manifold and the
engine coolant sensor on the back of the head- nothing has changed
either time. Previously, I had an engine coolant sensor fault code.

Now that I've checked codes, there are none.

For the duration of the testing, I'm running Sunoco Ultra 94.

Car has sat with the battery disconnected for about a week at a time
between testing.

I'm going to look at the wastegate frequency valve and the throttle
potentiometer next.

This problem is driving me nuts- all the more reason to get a C5 Vette,
soon!

Taka
150hp turbo quattro, used to be 265hp

_______________________________________________
S-CAR-List mailing list
S-CAR-List at audifans.com
http://www.audifans.com/mailman/listinfo/s-car-list