Originally posted by dougie2
Matt, Surely you mean that your idling with 7 degrees of advance, not 7 degrees BTDC. I have also noticed that the leaner mixtures want less timing. I don't have to worry about emissions, so I tune my engine richer with more timing and my engine seems to like that the best... at idle and cruise. On the engines I've tuned that have to pass emissions, a good compromise has been ~14.5:1 AFR and 17-19 degrees of TOTAL ignition timing... and the cars pass with flying colors. It's interesting that moving the lambda sensor closer to the head helped the response time and thefore injector pulsewidth stability. I never could understand why some of you guys had such bad luck getting the idle pulsewidth stable, but this makes sense. How far from the turbo is your lambda sensor now? I also shoot for ~24 inches.

Well 7 degrees advance is technically 7 degrees BTDC, referring to crank degrees..at least thats how i've always looked at it...Also too, i noticed it idled really nice with a richer mix and more timing at idle, but it tends to foul out the plugs easier and blackens them much faster as well..not to mention getting more carbon buildup on the wideband sensor..Leaner idle wiht less timing creates a little higher EGT, around 900 F, which helps with minimizing carbon buildup too.

Right now i'd guess the distance from the turbo outlet to the sensor is approx 20-24". My o2 sensor settings are 24 samples per ignition event, 1% steps. I used to run 16 samples, but the A/F was more jumpy at idle, when the sensor was farther away. Moving it closer let me run more samples, with a less jitter of the A/F. I just seem to still get a slight lean missfire at any A/F over 14.5 or so, just a littl stumble or burble out the exhaust..I think if i can get my cams zeroed out like stock, it would run perfect at idle..Its still a street car, so im a little "idle anal" lol