[s-cars] STILL fighting ignition problem

[Bruce Mendel]

I have experienced PSO failures on four different S-cars.....in three of
them, the failure developed slowly and was intermittent, and then eventually
went to full-time. Replacing the PSO in question solved the problem
completely.

So I don't think it's a binary problem.

Bruce
----- Original Message ----- 
From: "Robert Myers" <robert at s-cars.org>
To: "Brian Powell" <powellb at gmail.com>; <s-car-list at audifans.com>
Sent: Tuesday, November 23, 2004 9:02 PM
Subject: Re: [s-cars] STILL fighting ignition problem


>
> Brian,
>
> In my extended investigation of a somewhat similar miss I discovered
> something.  I had believed, like you, that the PSO acted to provide a
> signal to the coil in order to inductively fire the plug.
>
> WRONG!!!
>
> +12 volts is present at the firewall connection for the coils and the PSO
> is located on the ground side of the coil.  The PSO does not provide a
> signal it provides a ground path for the coil primary as a result of
> receiving a signal from the ECU.  I was surprised to discover this but
> that's the way it is.
>
> IME, a PSO is either good or bad.  If it is bad you will have a full time
> miss.  Period.
>
>
> At 02:30 PM 11/22/2004 -0700, Brian Powell wrote:
>
> >Thanks to all who responded last week on ways to test my coil packs.
> >To revisit, I have hesitation (misfire) under boost. I have new plugs
> >and coil boots. I tested the coils with the spark gap tester up to
> >about the 42,000 volt mark and all coils sparked similarly (if
> >sporadically) at that length (around 1"). I then tested the resistance
> >of the coil packs themselves (thanks S. Eiche), and they are all
> >within reason at ~13 MOhms.
> >
> >So, by both tests, all coils are performing similarly. Thus, what
> >next? I look to the POS. Possibly, the POS isn't allowing enough
> >through to create a spark? The POS failure has been reported to be bad
> >under boost in rare cases.
> >
> >My wife has a 96 A4Q (12v V6) which has a POS (strange system: only
> >one POS for the V6), but built by Hitachi not Bosch. The part number
> >for the POS on the A4 and the POS for the S6 is the same, but, the S6
> >has an "A" appended and (as I said) is made by Bosch. Both have a 3
> >wire and 4 wire connectors with the same wiring layout.
> >
> >My first question is: can I swap in the A4 POS to use as a tester for
> >the S6 without blowing the Hitachi?
> >
> >Second, any other suggestions for a high boost (20+ psi) misfire?
> >
> >Thanks in advance.
> >
> >--
> >Cheers,
> >Brian
> >_______________________________________________
> >S-CAR-List mailing list
> >S-CAR-List at audifans.com
> >http://www.audifans.com/mailman/listinfo/s-car-list
>
> Bob
> Random Bushism: "That's why I went to the Congress last September and
> proposed fundamental - supplemental funding, which is money for armor and
> body parts and ammunition and fuel." - Erie, Pa., Sept. 4, 2004
> _____
> Robert Myers  304-574-2372
> Fayetteville, WV
> '95 urS6 - Cashmere Grey
> _____
>


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