[s-cars] Non S-Car: A4 Stumble

[Brian Powell]

Paul,

thank you for the reply. I have tested the plug wires for resistance,
but, I haven't tried swapping cables around. I will try that.


On Wed, 5 Jan 2005 22:01:54 -0600, Paul  Gailus <gailus at mindspring.com> wrote:
> With a "waste spark" ignition coil that feeds two spark plugs,
> it's possible to have an early breakdown from faulty insulation
> on one side of the coil secondary winding but not on the other side.
> So one spark plug could be misfiring and the plug on the
> other side of the same coil could still be working fine.
> In fact, even if one of the coil outputs is shorted to ground,
> the other side should still have a nice spark.
> 
> If you have enough slack on the spark plug wires you could
> exchange the wires from cylinders 5 and 3 to the coil to
> see if the misfire code then moves to cylinder 3
> (confirming a bad coil).
> But they probably trimmed the wires too neatly for that ;-)
> 
> Paul
> 
> ----- Original Message -----
> From: Brian Powell <powellb at gmail.com>
> To: <s-car-list at audifans.com>
> Sent: Wednesday, January 05, 2005 3:43 PM
> Subject: [s-cars] Non S-Car: A4 Stumble
> 
> > Greetings listers,
> >
> > My wife's A4 (96 12v V6) is having a stumble under load problem that I
> > cannot trace down. I have tried Audiworld, etc. so I will try here.
> >
> > Car seems fine, idles fine, etc. Sometimes under load (accelerating
> > from 2k rpm in 3rd gear) the car begins to stumble badly. It feels
> > like a pre-detonation and drop back in timing; however, the gas is
> > what she has always used without problem. I hooked up VAG-COM and
> > sometimes an error code is logged:
> >
> > 16689 - cylinder 5 misfire detected
> > p0305 - 69-00 - cylinder 2
> >
> > (I'm not sure what that cylinder 2 part of the above message means).
> >
> > This code does not always appear after a stumble incident (if I clear
> > the code, go drive and get it stumble); however, it always comes
> > eventually. I have moved the plugs around, tested the coils, plug
> > wires, PSO, etc. and nothing has had an impact. This car has three
> > coils and one PSO so, if the coil were the issue, I should register
> > misfires on cylinder 3 also (since 5 and 3 are on the same coil).
> >
> > It doesn't ever turn on the CEL, but, sometimes does enter the above
> > error code. The misfire detection (as I understand it) will flip the
> > code if there are any slight deviations so it is only an indicator, I
> > suppose.
> >
> > I have thought about poor fuel delivery, FPR, etc.; however, any of
> > those issues should register misfires on other cylinders, not just 5.
> >
> > Anyone have any tips or suggestions?
> >
> > --
> > Cheers,
> > Brian
> > _______________________________________________
> > S-CAR-List mailing list
> > S-CAR-List at audifans.com
> > http://www.audifans.com/mailman/listinfo/s-car-list
> 
> 


-- 
Cheers,
Brian