[s-cars] Re: Detonation - I think

[William Noland]

Yep, sounds like knocking. Could be bad gas. Perhaps, you could live in
California, which = bad gas. Other thing to consider, if the motor has
some miles on it, is carbon build up. Eventually, enough carbon will
buid up in the combustion chamber to raise the compression ratio
slightly. Given that the the compression ratio is already high for a
turbo motor, it doesn't take much to push it over the edge. A "carbon
wash" can be done with the motor and everything in place. I've had it
done on high compression, normally aspirated, high mileage motors with
good results.

Your knock sensors will avoid any major engine damage, in the short run,
so not to worry.

Bill Noland


>I am getting a rattling sound like dried peas being poured onto the floor -
>when there is some load on the engine (4th and 5th gears, from half to WO
>throttle). If I back off throttle, the sound disappears. As long as I use a
>light foot, there is no rattling sound. This is a first for me but it sounds
>like the way I have heard detonation described.
>
>This is something that has popped up today and I can't think of anything
>except something restricting fuel flow or low fuel pressure.
>
>1. Can this be anything other than detonation?
>
>2. How can I check flow? How much fuel pressure should I be seeing?
>
>
>Worried,
>
>Rich
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