Thu Nov 20 11:46:45 EST 2003
There can exist situations where the ECU is letting the turbo spin right up
prior to modulating the WGFV.
At this point you are in the condition what I perceive as 'overboost'. It
will allow the turbo to spin up very fast to get things moving.
Then the WGFV steps in... if the spring is wound in too tight, there can be
too long of a lag between when the WGFV admits boost to the lower chamber
and when the WG opens. I don't have hard numbers to through around, but I
would think that the ECU would not just SLAM open the WGFV to correct this
overboost. I have seen it on my boost gauge as you all have I'm sure.
3rd gear pulls at WOT the boost builds to 25 PSI (in my case) then gradually
comes down to about 22 PSI.
With my current TAP stage 3 ware, I had a problem of overboost heat and
If I pinned it I would build very good boost, but after about 5 seconds of
sustained overboost the ECU would shut it off.
The WGFV slammed open, boost dropped to 1.2 to 1.5 BAR (ABS) and would stay
that way until I did a 100 MPH reboot of the ecu (shut off the car). After
talking to Igor (Ivor ?) finally he stated that in the box where
instructions that said to crank back the WG spring perch to 2 1/2 turns from
contact with the perch.
This has allowed the wastegate to respond faster to the limited WGFV opening
values. The results is the boost rolls back much smother and in time to
stop the ECU from shutting the fun down.
Take this all as subjective advice on the workings of the WG and WGFV. I did
not dissect the code of the ECU nor did I design the WG plumbing. I have
just seen the results of how the spring compression can affect the boost
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