[urq] Knock sensor ?

[Claus Vegener]

Remember the purpose of knock sensors:
The ECU advance the timing until knock is heard an back up a bit.
Advanced timing normally gives most power and economic.
 So with high octane fuel you automatic are running more advanced.
If a less sensitive sensor is used, the risk is knocking because it don't 
hear the knock's until a piston is gone !
So the problem is not fault-codes or not. It is the life of engine.
Claus

----- Original Message ----- 
From: "Louis-Alain Richard" <larichard at plguide.com>
To: "'Tony Hoffman'" <auditony at gmail.com>; <dgraber460 at aol.com>
Cc: <seiche at shadetreesoftware.com>; <urq at audifans.com>; 
<quattro at audifans.com>
Sent: Monday, October 27, 2008 6:12 PM
Subject: Re: [urq] Knock sensor ?


> Non expert here. A knock sensor is a mike that listen the engine. While 
> they
> are all the same electrically, I guess that each different unit is tuned 
> to
> listen to some specific frequencies, different from engine to engine. That
> could explain the different part numbers, and explain also why some units
> work perfectly on different engines : you can install a less sensitive 
> knock
> sensor on a smooth engine, but the opposite  will trigger some codes more
> easily I guess.
>
> My 0.02,
>
> Louis-Alain
>
>
> -----Message d'origine-----
>
>
> I've done it before, on a V8Q. Had a bad one, used a known good one
> from a 5000TQ. It cleared the code, so I'd assume there's not a
> problem with switching them. Since they are all basically a
> piezo-electric crystal designed to generate voltage at a given
> frequency, I don't see why there would be a difference.
>
> However, without a dyno (before and after runs) I can't be 100% sure.
>
> Perhaps someone out there has more info, but until then, I'd certainly
> swap them out and see if that clears the code. It can't hurt anything.
>
> Tony
>
>
> On Sun, Oct 26, 2008 at 6:01 PM,  <dgraber460 at aol.com> wrote:
>> Any experts (or non experts) know if knock sensors can be exchanged 
>> across
> engines?
>> I'm trying to diagnose why I'm getting a sporadic check engine light?in 
>> my
> recent 20V 3B motor in my URQ. The knock sensor with a suspect wiring at 
> the
> block has a part number of 077-905-377A (& 0261-231-040).
>> The code stored earlier, and cleared was "00540 003 - Knock sensor (KS)
> 2-G66 No signal".
>> A sensor I picked up yesterday at the breakers [an MC engine I 
>> believe]?is
> 034-905-377A (& 0261-231-004).
>> Can these be interchanged?
>> Yes - the one on the motor was torqued to spec.
>> TIA
>>
>>
>> Dennis Graber
>
> _______________________________________________
> Audifans urq mailing list
> Send posts to: mailto:urq at audifans.com
> Manage your list connection: http://www.audifans.com/mailman/listinfo/urq
>
> North American Celebration of the 25th Anniversary for the urquattro: 
> http://www.urq25.com/
>
> Pictures/Polls/Database at: http://autos.groups.yahoo.com/group/urquattro/
>
> You can help keep the audifans site running by shopping at 
> http://audifans.com/shop/