[urq] stumble at high boost/full throttle

[fdekat]

> ------------------------------
> 
> Message: 6
> Date: Fri, 20 Feb 2009 10:17:55 -0800 (PST)
> From: Gary Brown <gmbchef at sbcglobal.net>
> Subject: [urq] stumble at high boost/full throttle
> To: urq at audifans.com
> Message-ID: <538.30029.qm at web82105.mail.mud.yahoo.com>
> Content-Type: text/plain; charset=iso-8859-1
> 
> Hey all-
> ?
> ?Car is running great, but.....
> ?
> At full throttle over 14 psi, car stumbles and my A/F gauge goes to lean.
> ?
> ?Checked throttle switches...both good.
> ?
> ?Check CPR hoses....all good.
> ?
> ?No vacuum leaks.
> ?
> ?If I back off just a bit, I get stoich/rich.
> ?
> I've read it could be ignition related. Plugs are new (maybe 2500 miles).
> ?
> I checked the wires....I have?two that read " 0", two that read " 5.xx" and
> one that reads "11.xx" 
> ?
> Idle is great and highway driving is great, just this high rpm boost issue.
> ?
> Gary?
> 
> ------------------------------


May or may not be related to your problem:

As reported by the O2 sensor, a miss makes the O2 senesor "think" lean (as ,
the sensor sees all of the 'unburnt' oxygen as way more than normal).


I've heard of an S4 motor getting toasted that way: 
Coil pack was bad/flakey, so O2 sensor thought 'mixture lean'. ECU richened
mixture accordingly. (So, now, mixture is really WAY too rich for all the
firing cylinders but OK as an 'average' mixture as seen by the O2 sensor.)
Extral fuel was really washing down the cylinder with no spark. Oil
eventually got too thin from being diluted with  all the gas, and main
bearings spin.. :-(

=Frank=