[s-cars] burned out plugs and leads

[Fred Munro]

Hi Mike;

Being a firm believer in Occam's razor, I'll ask this question first: are
the plugs tight? The plugs in these engines tend to loosen in use (several
listers have blown plugs out of the engine - that REALLY destroys the lead
and coil). A loose plug doesn't transfer the heat to the head as
effectively, overheating the plug. You should check the torque on the plugs
at every oil change, particularly after a new set has been installed.

If the plugs are tight, as you have mentioned a lean mixture is the next
likely cause. Install a wideband O2 sensor (or tap into the existing O2
sensor with a LED readout) and monitor the mixture during driving. This will
pinpoint any mixture problems. The ECU is supposed to detect lean or rich
mixture via the O2 sensor and adjust accordingly, but if the O2 sensor is
dead the ECU will be running open loop without mixture trim.

HTH

Fred Munro
'94 S4


-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com]On Behalf Of Michael Mulholland
Sent: December 5, 2004 1:23 PM
To: s-car-list at audifans.com
Subject: [s-cars] burned out plugs and leads


here we go again....my sons 95 s6 began misfiring this morning just as it
had done many times before. in october we greatly enriched the dealer and
lost the car for 30 days for the same trouble. this time it was spark plug
#1 that totally evaporated its core and elbow platinum connectors
(previously it had been # 2 ) it then destroys the porcelain and the lead.
the pos have been replaced along with new plugs F5DPOR, new leads and all
new coils. the other plugs look overheated and i suspect a lean mixture as
the cause. the dealer says that all is ok with the fuel.
help please
mike
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