Reading the crank and OBDII (Camaro)

[Peter Wales]

>I was reading the service manual for a '95 Camaro the other day, and saw
>something that looked weird. For the LT1 engine (5.7 liter V8), it seems
>they use TWO crank triggers. One low resolution, and one high resolution.
>If I recall correctly, the low resolution was 4 pulses per crank revolution,
>and the high one was 180 pulses per revolution.
>
>Does anyone know the reason for this? Is it some sort of failsafe, ie
>if one sensor failes, the engine runs in  'limp home mode'?

My guess is that they wait for the 4 tooth one to pass to identify 90 deg
BTDC and the count the 180 one to get within 2 degrees of the correct timing
then set the  counter off to delay until the timing comes correct.

Also, I would start charging the coil up at 90 deg BTDC and use a variable
dwell angle


 
Peter Wales
President Superchips Inc
Chairman Superchips Ltd        "Timing is everything"