Why ping at partial throttle?

[Philip Lochner]

Hi Guys
 
Now that I've got timing working I've been road tuning....
 
However I find that at full throttle I can advance my timing MORE than at partial throttle.  In other words, if I'm doing eg 3000rpm at full throttle it does not ping but as soon as I back off the loud pedal a little (at the same revs), pinging becomes most audible which would mean that at lighter loads I may have to RETARD my timing at those rpms.
 
Is there a reason why this would be or should I have my ears tested and become a painter?
 
Kind regards
Philip Lochner

Posted by email.

[TT350chevelle]

Are your decel settings reducing fuel causing a lean condition?

Brad J.

[Ira]

At 03:10 AM 03/08/2006, you wrote:
>mean that at lighter loads I may have to RETARD my timing at those rpms.
>
>Is there a reason why this would be or should I have my ears tested
>and become a painter?

Could be going lean which could increase the chance of ping.

Ira


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Posted by email.

[jonfx4com]

I suggest you go richer through the range (re fuel) just as a test then you will know if its your fuel or your ears. My ITB's make an intake sound that is very like detonation at part throttle. It seems unlikely you would need more retard at higher vacuum, very unliklely indeed.

Jon