[s-cars] Need Diagnostic Help

[chad clark]

Bob, I must add that while you are sure it's not a failing coil pack, I
would like to relate my experience. I had an opportunity many years ago to
help a friend diagnose a sudden and abrupt power loss during WOT in a
chipped '93 car. As soon as boost came on, massive stalling/bucking. But, as
soon as you backed off the accelerator and ran through the rpms with out any
boost, no bucking was felt. Eventually he swapped a new coil pack cylinder
by cylinder, went for a test drive and sure enough, coil 4 was toast.

Try the simple things first as others have mentioned = clean contacts and
such. It could be many things. Just wanted to add another experience with a
failing ignition coil. HTH,

Chad 


on 12/12/03 1:30 PM, Bob Rossato at bob.rossato at att.net wrote:

> Hello fellow S-heads,
> 
> A friend of mine is having some intermittent cutoff problems on his S4.
> It happens during wide open throttle.  He states that it is not like a
> misfire, it's more like a hard cutoff such as hitting the rev limiter,
> though he's nowhere near the rev limit.  Has happened a handful of times
> over the last few weeks.  When it's not acting up it pulls strongly, so
> I wouldn't suspect the usual ECU boost line coming off as it wouldn't
> reseal it self.  And besides, he's adamant that it's not just a loss of
> boost, it's a complete loss of power.  Again, only during WOT.  Ease off
> on the throttle and the engine comes back.  I also wouldn't suspect the
> POS or coils as I would expect that to be more of a misfire, not a
> complete loss of power.
> 
> We checked the codes today and got the following 3 codes:
> 
> 00519 - Intake Manifold Pressure Sensor (G71)
> 06-10 - Signal to High - Intermittent
> 00561 - Mixture Adaptation
> 14-00 - Adaptation Limit (Add) Exceeded
> 00544 - Maximum Boost Pressure Exceeded
> 27-10 - Implausible Signal - Intermittent
> 
> The 00561 mixture adaptation I've seen before on my car and others but
> I've never noticed anything wrong performance wise so I don't think
> that's the first thing I'd chase down.  The 00519 & 00544 are more
> relevant I think.  Is this an indication of a problem with the WGFV?  We
> will be checking the line to the ECU and water trap, as well as boost
> hoses anyway just to make sure.  Any other thoughts?
> 
> The car is a '94 S4 with ~53k miles.  Completely stock.  And let's see,
> what else... oh yeah, it's Pearl White if that helps.
> 
> Bob
> 
> 
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