[V6-12v] Pinking under light throttle

[Tom Christiansen]

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.

Tom


On 8/28/06, James Whitehouse <james_whitehouse1 at yahoo.co.uk> wrote:
> Another one for your perusal:
>
> I have some light 'pinking' under light throttle. It appears to be at a very
> specific point of throttle pedal travel, just past idle, and will not occur
> when you accelerate a little harder, or at WOT.
>
> We may find, while stripping down to do those head gaskets in a few weeks
> time, that everything is 'coked up', but I'm dubious as I always use premium
> grade 'super unleaded' fuel and regularly run a fuel system cleaner through.
> Plus the spark plugs were still perfect when checked recently, after 30,000
> miles, so I'm thinking the combustion chambers are probably all good.
>
> Anything else that can cause this? Dodgy knock sensor, etc?
>
> Cheers,
> James
>
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