I've owned two Syncro Westys over the years, '87 and a '91, Both of them
needed this repair. The symptoms only occurred in these vans in temperatures
under 10 degrees F, felt like someone was turning the ignition off and on.
In both cases I could marginally drive if I kept the accelerator as constant
as possible, with the AFM only acting up when decelerating or accelerating.
I was told it was the potentiometer in the AFM freaking out in low temps,
and doing the business you describe. The upgrade acts like a surge
suppresser and fixed the problem instantly. However, you would have never
known there was a problem if these vans resided in a warm climate.
-Wayne

> Subject: Re: Strange problem with '91 Carat
>
> There is a factory service note on the filter capacitor that could solve the
> problem.
>
> I think the eminent Mr. David Beierl (sp) has details on the installation.
>
> In essence, the ECU receives a faulty signal from the air flow meter.  The
> nature of the signal is noise imposed on an otherwise slowly changing
> voltage.  The ECU then defaults to shutting off the injection pulses until
> the signal is less noisy.
>
> I would suspect a slightly worn or dirty contact set on the AFM but
> installing the capacitor is an upgrade that will help "tune" the AFM
> circuit.
>
>
> That factory piece is a plug in upgrade.  But it's pricey.
>
> pensioner