bizarre stalling behaviour 87 4kcsq

[John Larson]

Since the mixture is continuously adjusted by the O2 sensor, and a rich 
mixture is a big factor in stalling/hunting on and after decel, I would 
hesitate to say "My car idles  fine with no O2 sensor" in a discussion of 
decel problems. I see this kind of stalling a lot here at the shop, and it's 
most often associated with a rich mixture.  Even carbureted cars do this. 
My experience (gained in 32 years of working on Audis) leads me to encourage 
the guy with the stalling problems to look into it.  Computer controlled 
engines do NOT idle just fine with their systems disabled, at least not in 
relative terms.  While earlier Audis don't have a completely integrated 
engine management system, they have enough to make them dependent on the ECU 
to run properly, and the ECU depends on the O2 sensor signal.   Cars with 
working O2 sensors also tend to exhibit better fuel mileage.  John

----- Original Message ----- 
From: "Robert M" <porter_t_dog at hotmail.com>
To: <j.d.larson at verizon.net>; <quattro at audifans.com>
Sent: Monday, May 09, 2005 8:10 AM
Subject: Re: bizarre stalling behaviour 87 4kcsq


>
>   Sorry dog- you must have me mixed up with someone else.  My car idles 
> fine with no O2 sensor.
>
>
>>From: "John Larson" <j.d.larson at verizon.net>
>>To: "Robert M" <porter_t_dog at hotmail.com>, <quattro at audifans.com>
>>Subject: Re: bizarre stalling behaviour 87 4kcsq
>>Date: Mon, 09 May 2005 08:06:52 -0700
>>
>>Since the O2 sensor is an integral part of the engine's operating system, 
>>no wonder you're having idle problems ................  John
>>----- Original Message ----- From: "Robert M" <porter_t_dog at hotmail.com>
>>To: <j.d.larson at verizon.net>; <quattro at audifans.com>
>>Sent: Monday, May 09, 2005 7:58 AM
>>Subject: RE: bizarre stalling behaviour 87 4kcsq
>>
>>
>>>
>>>  Yeah, thanks.  No sensor on my car; deleted.
>>>
>>>>From: "John Larson" <j.d.larson at verizon.net>
>>>>To: <porter_t_dog at hotmail.com>, <quattro at audifans.com>
>>>>Subject: RE: bizarre stalling behaviour 87 4kcsq
>>>>Date: Mon, 09 May 2005 07:27:01 -0700
>>>>
>>>>Robert said:  " When I clean my ISV I like to lube it a bit afterwards; 
>>>>silicone spray
>>>>or the like.  Possible it's _too_ clean?  Make sure the contacts are 
>>>>good
>>>>too- clean them and use some silicone grease to seal it up on 
>>>>reassembly."
>>>>
>>>>Per Bosch and various auto manufacturers, NEVER use silicone products in 
>>>>or around the intake system.  It kills the O2 sensor.  HTH, John
>>>>
>>>
>>>
>>
>
>