Re: Re: rotor for 20v turbo engine

[C1J1Miller@aol.com]

In a message dated 11/5/98 11:29:44 PM, wallace@remdesign.com wrote:

>But that would be the fault of the ECU and/or the distributor itself,
>not the distributor rotor, as I see it. The job of the rotor is to make
>sure there's a good easy path to whichever plug is going to be fired; if
>you have a narrower rotor, you make that path a little more difficult in
>the case of extreme advance, but you don't succeed in preventing
>it--which, at any rate, would result in a misfire. 

I'm not sure if we're talking about the same thing... 
cheap ascii art follows:


 [-------]             [   ----   ]
    [     ]                    [     ]
    [  o  ]                   [  o  ]

10v rotor             20v rotor

As I understand a coil, it builds up the voltage, then discharges.  Not
instantaneous, but takes some time.  The longer metal piece (-) will get close
to the spark plug wire before the shorter 20v rotor will and the spark will
occur first.

The ECU says to the coil when to fire; with the longer than expected 10v
rotor, the coil may fire to the cylinder before the ECU thinks it will.  The
ECU doesn't measure when the spark occurs, just knows when it _should_ occur.
It advances/retards ignition timing based on 3D maps in the computer memory,
and on ignition knock, temp, rpm, load.  But it doesn't have an inductive
pickup for when the spark actually occurs.
chris