Fw: Re: Still Surging

[rguzz@mindspring.com]

-----Forwarded Message-----
From: rguzz at mindspring.com
Sent: Aug 23, 2005 9:04 AM
To: Taka Mizutani <t44tqtro at gmail.com>
Cc: 20020v at audifans.com
Subject: Re: Still Surging

Taka,
I rarely drive this car hard. Surging is most noticeable at 3k RPM say in third. I'll have to put the boost to her and see what she does...my mechanic and friend, without investigating, thought the chipset might be at fault, as you suggest. There is a stiffer WG spring with this TAP set maybe it needs adjusting? In a bit too far?
Boost gauge sits on 16 PSI under full throttle, never goes higher. When it's surging the car isn't under boost at all.
Is there a fuse or relay to the ECM? I changed the 02 sensor and was told sometimes the ECM needs to be re-set if it doesn't sense the change from the new sensor.
The list of possibilities is long...but ECU seems up there, unfortunately. Perhaps a swap to see if that fixes anything ...
Other ideas?
Also did the fuel filter, pump is quite new.
Rich


-----Original Message-----
From: Taka Mizutani <t44tqtro at gmail.com>
Sent: Aug 23, 2005 8:17 AM
To: RGuzz <rguzz at mindspring.com>
Cc: Audi 200 20v Mailing List <200q20v at audifans.com>
Subject: Re: Still Surging

Rich-
Can you describe the surging in terms of what it looks like on your
boost gauge (hopefully you have one)?

With the Lehmann chipset in my old car, I would have full boost of
19psi in 4th and 5th gear, but it wasn't completely without hiccups-
stomping on the throttle in 3rd would result in a quick boost to
19psi, then an immediate dip (I think the ECU was pulling back timing
each time), then a more gradual climb (but within 1-2 seconds tops) to
about 16psi. Rolling on the throttle resulted in a much less
noticeable dip in boost- the car just felt a bit slower to respond, no
real feeling of loss of power, but the boost gauge told the whole
story- a moment of dip, then 16psi.

I've never experienced boost surging in the 200, I think it would be
the result of poor software tuning. I have experienced it in our old
A4 1.8T- max boost, then surging- back and forth from 12 to 15psi. It
would only happen in the winter with oxygenated gas.

Throttle position sensor- I don't know if you would have surging when
cold with a bad TPS, though.

Taka