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Re: Flywheels: them big, round, heavy frisbe

On Mon, 13 May 1996, Dave Lawson wrote:

> Bentley manual, these 2 pins are shown as being magnetic engine
> test pins, or some such description. They aren't used for normal
> operation, but for some diagnostic test, which I haven't found a
> description for yet. They appear to be in the same location on
> each flywheel.

I thought that these pins were indeed used for normal use.  Scott?

> As RDH has figured out for a TQC, the ref mark pin signals 60 degrees
> before TDC and the computer counts flywheel teeth from the ref mark
> pin until the correct amount of ignition timing advance is achieved.

Does the ECU actually count the teeth?  It is possible, (and common on 
other ECUs) to guess at TDC after making the reference signal by knowing 
how fast the engine is turning.  The ECU merely trips a timer, and fires 
the plug at the prescribed point.

> at every speed. I am thinking of just changing the timing maps in my
> ECU by this amount to compensate for this bias. I know people have
> said before that this is well within the range for the knock sensor timing
> adjustment( ~7 degrees), but if I want to eek out that last bit of timing
> advance I probably need to adjust the ECU map. Suggestions? Thoughts?

I fully agree with changing the timing maps, since you would be chopping 
off 2.6 degrees of range from your knock sensor control.

Do you have the ability to change the timing maps?  Where are they on the 
chip?  I have spare chips....

> More than anyone ever wanted to know about turbo flywheels.....

There's more I'd like to know :-)   How heavy are they?


Graydon D. Stuckey								
Flint, Michigan   USA
'86 Audi 5000 CS Turbo Quattro, GDS Racing Stage II