Aargh...
Yesterday Connie and I took the C5Z out to Apalachicola and St. George Island to meet up with Mike and Donna for lunch. Car ran just fine. Up till we stopped in at Myway Seafood to stock up on some shrimp. When we were getting ready to leave, I kept getting Reduced Engine Power faults at startup. Had to try it several times before the error would go away.
Anyway, I went and made some adjustments in the tables that do the comparison of actual airflow to predicted airflow (C6101 and C6102) and raised the values 30 percent. The car started up fine after flashing the new tune, but obviously I need to run it for a while to see if that fixed the problem or not.
There is another value I need to fiddle with that controls the conversion of throttle body stepper motor steps in relation to the amount of airflow per step. Changing from the stock throttle body to the 90mm LS2 version changes this formula and there is a value (B4349) that is used to enter a scaler value. Stock is 0.0255. I have mine set at 0.0330. Some people say the value should be SMALLER for a larger TB, like 0.192, but when I use that value, the engine will not stay running after I blip the accelerator.
Since this REP is happening at startup, it's possible that the airflow values at that time are not correct, triggering that fault. Or it could also be an actual hardware intermittentcy. The only error code I can pull up is a P1516, which indicates a throttle position mismatch between commanded and actual throttle blade position. So it's possible that the throttle body blade position sensor might be flaky instead of something programmable in the tune. I guess I need to find a description of exactly what the PCM is testing upon startup to get a better feel for what this is telling me exactly.
Ah well, guess I don't want to get too bored with everything running perfectly on the car....
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