[s-cars] Pauls' problem (with car)

[Calvin & Diana Craig]

Paul,

You said it stumbled after it started.  I don't believe this is symptomatic
of a CPS since it is only used to start the car; once the car is started,
probably a threshold in code set by a set number of rpms, the crank position
sensor takes over and the cam position sensor is taken along for the ride.
At least this is the way it is coded in 99.9% of all the car ECU's I have
seen.  The motronic is probably the same.  The only way I can see the CPS
causing this is that it caught enough to get the car somewhat started but
the rpm's weren't over the threshold to stop looking at the CPS sensor and
it started going flaky again.  If your rpms were over 600-700 during the
stumbling event and the Motronic works the way I think it does, there is
almost (I'll never say never with Audis) no way it can be the CPS.

The stumbling, to me, indicates a fuel starvation problem.  Maybe fuel pump
or FPR.  I still stick by the fact that the first thing I would do is spend
$35 for the FPR and replace it.  Especially since your codes did not reveal
any CPS abnormal activity, which is very unlikely if it is the CPS.  You
could satrt with the Fuel pump or CPS, but both of those are going to be
about $100 in parts and hours of labor.  I always start with the easiest
(cheapest) and work from there.

--Calvin



>Cross referencing them now, will post results later when I know what they
>are.  Interestingly, when dumping (hot start, shut off, repeat), car
>"hardstarted", meaning, crankcrankcrankcrank, stumblestumble grudgingly
>starrrr...starrr... started.  Is that also symptomatic of a fail(ing) CPS?
>Or signs of trouble elsewhere?