the "0" on the flywheel

Huw Powell audi at
Wed Sep 13 22:11:59 EDT 2006

> what i'm getting at is that i believe that i'm hearing a little bit
> of pre-ignition when the guage reads 15psi.  the car is pulling just
> as hard, and according to my newly-installed air-fuel meter, it's
> running nice and rich, but i'm really nervous about this noise.
> it sounds like the sound of a hot exhaust cooling down.  as soon as i
> hear it, i change gears, or get my foot off the loud pedal.
> is this the sound of fully functioning knock sensors playing around
> with the fringes of pre-ignition?  or is my timing off by 6 degrees?

OK, we need to start distinguishing between "spark timing" and "valve 
timing" here.

I can't remember what your car is, but all that talk about boost makes 
me suspect it has an MC engine, which manages the spark timing relative 
to crank by computer, and "can't" be wrong (after starting, it uses the 
reference on the flywheel).

The valve timing issue is what I thought the worry was - you're not sure 
your cam and crank are in time.  I think if they were off by six degrees 
things would be all screwed up, but I'm not sure.

Do the #1 cylinder test for TDC and compare to the cam pulley mark.

Huw Powell

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