[s-cars] Partial Throttle Surging

[Russ Panneton]

On Mon, 26 Aug 2002 11:48:25 -0600, "mlp" <mlped at qwest.net> wrote:

>
>In my car I when boost gets to @ 12 psi (a number suspiciously close many
>waste gates  reputed "default" base spring pressure), then will begin an
>increasingly aggressive swing, pulse between 12 / 18+psi as seen on,
>reputably reliable, digital boost gauge.  By "aggressive" I mean one will
>see almost instantaneous pressure swings from the base 11 to 12 up to 18~20,
>13, 14, 15 & 16 etc. don't get to play much if any part in the natural
>progression of events.
>

I believe our boost controller has at least a couple of different boost maps
to choose from.  Is it possible that one of the knock detectors hears
something and the ECU switches to a less aggressive boost map?

My 95.5 S6 mit RS2 and Lehman stage 3 firmware and 3 bar MAP sensor also
surges a wee bit only now but only at very small throttle openings.  I have
also seen the Check Engine light come on under very light trailing throttle
(gentle downhill road) but go back off the instant I touch the throttle.  The
ECU stores only an intermittent  "2413, Mixture Adjustment, Adaptation limit
exceeded" code.  My cats also smell stinky when this happens so I believe the
"running too rich" suggested symptom.  I'd suspect the O2 sensor but it's only
a one year old generic Bosch three wire sensor.  I'd suspect a sticky injector
but the car idles very smoothly.  Can anyone venture any other suggestions?
Do our fuel pressure regulators ever get flakey and not regulate well?


Russ
Guessing away in Nederland, CO
--
Russ Panneton                          russ at s-cars.org
Nederland, CO              "Too bad ignorance isn't painful"