[s-cars] STILL fighting ignition problem

[Robert Myers]

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
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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
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Robert Myers  304-574-2372
Fayetteville, WV
'95 urS6 - Cashmere Grey
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