I can't follow what you are doing with the piston stop by your description and tape. The stop doesn't stop the engine at TDC so touching the stop and making a mark means nothing by itself.

You put the stop in and rotate the engine clockwise until it touches and make a mark. Then, rotate the engine counterclockwise until it touches and make another mark. TDC is in between these 2 marks.

The computer does not compensate for the timing. 2* advanced means the timing is always 2* advanced compared to the programmed timing curves.


Quote Originally Posted by Fast355 View Post
If the 02 sensor was cooling off the engine would run rich, not lean.
When I learned the 1-wire O2 doesn't work in the collector of long tube headers, the engine went badly lean at idle. It would start working correctly again once the rpm's were brought up to the 1500+ rpm range.

The engine also tended to run a little lean at cruise in the 1500-2000rpm range, but that was a lack of adjusting the loop for the headers since it still occurred with a heated O2 sensor. At cruise I could hear the engine pitch slightly change every time the O2 sensor voltage went low. Some integer delay and O2 switching point adjustments were required to fix it.