[s-cars] Knock Sensors?

[Bill Clancy]

I just stumbled on this.   It confirms that the engine is detecting a knock.


If knocking is detected for an extended period of time, the ignition timing 
is retarded and the boost pressure is reduced. Ignition timing is retarded 
in 3° increments.

Should knock continue after timing retard, the ECU will enrich the fuel 
mixture to reduce the combustion temperature; should knock continue, the ECU 
will then reduce boost pressure to a predetermined level.  When knock has 
been eliminated, the ignition timing is returned to its normal value in 1.3° 
increments and boost pressure is returned to its normal value.

----- Original Message ----- 
From: "Bill Clancy" <clancybill at yahoo.com>
To: <s-car-list at audifans.com>
Sent: Tuesday, May 24, 2005 4:59 PM
Subject: [s-cars] Knock Sensors?



Does anyone know if there is a way to check the knock sensors?   Or is there 
a way to disable them temporarily to see how the engine runs?

I continue to get inconsistent performance.   It runs better with all the 
turbo leaks fixed and with new spark plugs... but I still feel the engine 
sort of sputter and back off a bit at WOT.    It's been suggested that the 
ECU senses a knock and backs off the timing.    I did do some road testing 
with the VAG-COM software on my laptop and I think I can correlate the power 
loss to the timing -- at WOT at @3500RPM the timing moved up to 12.8 BTDC, 
then it moved to 9.8 (I think that's the power loss I feel), and then back 
to 11 or 12.    On a good run the timing seems to stay at 12.8.   On a 
better run, sometimes I record 13 or higher.

I have another fuel/timing chip for 91 octane that Mr. Myers provided, but I 
am not yet convinced that the problem is knocking 91 octane fuel.    Or 
maybe it is.   Could it really be that simple?


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