NG Warm Up Stumble

[SJ]

From: "Brett Dikeman" <quattro at frank.mercea.net>
To: <audi at humanspeakers.com>
Cc: "SJ" <syljay at optonline.net>; <rggpa1 at yahoo.com>; <quattro at audifans.com>
Subject: Re: NG Warm Up Stumble


>
> Amusing anecdote: my 200q20v kept running even when the distributor
> cap was totally trashed.
>
> When it finally occurred to me to check there to solve an occasional
> misfire at idle (and I couldn't remember having replaced the cap or
> rotor...ever...) the bakelite around the center button (which was
> gone, who knows where) was cracked/chipped and scorched, > Brett
***** I forgot to mention that a few days ago, the wife's car, 90 100q, had
a slight ignition miss right after startup, and when under load.
I borrowed her car one morning and noticed the miss right away. No miss at
idle, but you could feel the occasional misfire when accelerating from a
stop. The misfire cleared up after a few minutes of driving.
The wife was aware of the problem but failed to tell me. When I questioned
her about it, she said "Oh yeah, its been doing that". "For how long has it
been doing this?" said I. She stopped to think and replied "I dont know, I
dont keep track of these things, thats your job". Grrrrrrrrrrrrrrrrrrrrr
The distributor cap was  not that old in terms of mileage.
I removed the cap, cleaned out the insides with alchohol, replaced the cap.
Problem solved.
The conditions for the miss were cooler weather and humidity. We have had a
spate of rainy weather here in NJ for the last 3 weeks.
Under certain temperature/humidity conditions, at a specific dew point,
moisture will condense inside the distributor cap and cause the ignition
miss. Under load, the spark energy will find the lowest resistance path to
ground . . .which now exists inside the distributor cap.
A few miles or minutes of driving results in enough heat being generated
inside the distributor cap to flash off any surface moisture, and the
ignition miss ends.
For the curious scientists out there, the theory for the "ignition miss unde
r load" can be found here: "Paschen's Law site:audifans.com".

SJ



-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.405 / Virus Database: 268.12.2/441 - Release Date: 9/7/2006