[V6-12v] Pinking under light throttle

[Chris Thorp]

On Aug 29, 2006, at 10:17 PM, Tom Christiansen wrote:

> James,
>
> Pinging happens when the fuel/air mixture is ignited at TDC of the
> piston. Reasons for why this could happen (my speculation).
>
> 1) Low octane fuel.
> 2) High compression (wonder what happens if coolant seeps into the
> cylinder through the cracked head gasket).
> 3) Crank sensor is getting sick. Can't sense TDC properly.
> 4) Incorrect fuel/air mixture I suppose. The knock sensor should take
> care of this.
>
> I believe both the crank and knock sensors will throw a trouble code
> if they become ill.
Check the ECU for fault codes.  The ECU has measurement blocks for  
knock counts and can switch between a couple timing maps.  (At least  
on my '95 A6)  If the ECU isn't seeing the knock, then maybe the  
sensors are bad.

-Chris