Losing boost st 4500 rpms

Henry A Harper III hah at alumni.rice.edu
Tue May 20 16:52:27 EDT 2003

That is a "feature" resulting from the engineering decision made by Audi in
selecting the "small" K24 turbo - unless it's going back down to no boost?
Boost is controlled to decrease at high rpm in order to keep the turbo from
overspinning. See http://www.sjmautotechnik.com/200tqbst.html for a graph
of what you should be seeing (and probably are?). Exactly how much is it
decreasing, and keep in mind the dash computer is not particularly known
for accuracy. Are you reading the 1.7 off the dash computer, or have you
scaled that by 2.5/2.0 to reflect your chip mod (actually pressure sensor
swap w/chip mod)?

Henry Harper
http://www.henry-harper.com  hah at alumni.rice.edu
1991 200 quattro, 118k, Hoppen chip
1988 GTI 16v, 236k, what's a chip

On Monday, May 19, 2003 7:54 PM, Alilio, Allan
[SMTP:Allan.Alilio at nasdaq.com] wrote:
> Is there anything that cuts back at 4500 rpms.  I can hit 1.7 bar then
when i get to around 4500rpms the boost will slowly decrease.  I changed
bypass valve to hyperboost valve and it helped a little.  Checked
Wastegate, Wastegate Frequency valve, knock sensors, mass air flow all
hoses and boots and still boost drops on me.  Please someone help.  I have
taken it to 2 Audi shops and they cannot figure it out as well.
 Compression test was done and 170 across the board, turbo was also checked
and it is good.  Mods on car are K&N filter, hyperboost valve, straight
through exhaust no cats, Hoppen chip.
> Thanks,
> Allan
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