[s-cars] Diagnosing misfire cause

[Jerry Scott]

You likely have a bad coil.  I have a new Beru 0040 100 043 coil that I will sell for $50 plus shipping. I also have a new  Bosh POS 0 227 100 043 POS for $45 plus shipping.  These are spare parts that I had left over after selling the 93 S4.

Let me know if interested.

It's not a good idea to keep driving the car with a misfire, since you are dumping unburned fuel into the non-firing cylinder.  This could burn out the cat-converter over time.  The best way to find it is to start pulling plug wires one at a time while the engine is idling. That is, if you can catch it while it is misfiring at idle.

Hope you find the problem.
Jerry

-----Original Message-----
From: S-CAR-List [mailto:s-car-list-bounces at audifans.com] On Behalf Of Tom Rodriguez
Sent: Wednesday, December 30, 2015 4:32 PM
To: s-car-list at audifans.com
Subject: [s-cars] Diagnosing misfire cause

Folks,

 

My '95 S6 is misfiring intermittently and I am trying to determine the cause.  When it misfires, it does so constantly at all engine speeds and under all levels of acceleration & boost, including at idle.  On some days the car starts well and runs well for a while, then begins misfiring once warm.  On other days it misfires when cold, and then clears up once warm.

 

I've read the technical advice provided at SJM Autotechnik on this subject, which points to either a bad ignition coil, a bad POS, or a bad fuel injector.  They also mention dirty plugs but mine look fine.

 

My problem is that every time I try to diagnose the cause, the engine refuses to misfire.  When it does misfire, I am not in a place where I can do any diagnostics.  It's very frustrating.  I'm hesitant to drive the car any long distances until I figure this out.

 

Thanks for any advice,

 

Tom

 

Tom Rodriguez

'95 S6, 267k miles

 

 

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