[s-cars] Re: Knock sensor failure?

[Mihnea Cotet]

Mike,

I hate sounding like I like to disagree with everyone, but I've never 
experienced lower boost with detonating mixtures, ever.

I know most of the stuff the Audi publications say, but my job is 
programming these 20vt ECUs and I can say for sure, boost isn't lowered 
when an engine detonates, nor is the mixture enriched. BTDT lotsa and lotsa 
and lotsa times.

HTH,

Mihnea

At 06:53 1/04/2004 -0700, Michael Wakefield wrote:

>For what it's worth, the following is from an Audi publication I have 
>(WSP-521-218-00). It describes the function of the knock sensors, and more 
>importantly says that the only
>way it will throw a code is for no signal. Unfortunately, it does not 
>address installation torque issues.
>
>"Cylinders 1, 2, and 3 are monitored by knock sensor I (G61), and
>cylinders 4 and 5 are monitored by knock sensor II (G66).
>
>Signals from the knock sensors are used by the Motronic control module
>for cylinder selective knock control.
>
>The ignition timing of an individual cylinder can be retarded if knock
>is detected. If knock continues, a richer fuel mixture will be used and
>the charge pressure is reduced.
>
>Knock control is adaptive, which means that the system will adapt to
>fuel quality and driving conditions.
>
>Self-diagnosis recognizes one fault which is "no signal".
>
>If a fault develops with either of the two knock sensors, the ignition
>timing will be retarded by 11 degrees and the fuel mixture will be
>enriched."
>
>Mike Wakefield
>Highlands Ranch CO
>93S4
>97Cab
>
>On Apr 1, 2004, at 4:36 AM, Mihnea Cotet wrote:
>
>>Phil, I must say I don't agree. I've BTDT in a few cases where the knock 
>>sensors had been overtorqued and the only effect this had is that the ECU 
>>wasn't seeing any knock activity when the engine was pinging like a 
>>churchbell. There are a few maps that the ECU is using in case of knock 
>>sensor activity in a 20vt ECU and I'm sure I know where they are and what 
>>they mean, and the ECU didn't give a damn about them although you could 
>>hear the engine pinging very audibly even in 3rd gear (where the load is 
>>a lot lower than in 6th gear for instance).
>>
>>Just my 0.02,
>>
>>Mihnea
>>
>>At 09:08 1/04/2004 +0200, Phil Payne wrote:
>>
>>> > I'm sure that knock sensors have failed from time to time but I would
>>>expect that the normal failure mode would be that it simply stop putting
>>>out a signal.  However, has anyone experienced a knock sensor failure in
>>>which the knock sensor becomes overly sensitive and reports knocking to the
>>>ECU when none is actually happening?
>>>
>>>Yes, if it's overtorqued.
>>>
>>>--
>>>   Phil Payne
>>>   http://www.isham-research.com/quattro
>>>   +44 7785 302 803
>>>_______________________________________________
>>>S-CAR-List mailing list
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>>>http://www.audifans.com/mailman/listinfo/s-car-list
>>
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