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turboberserker
February 16th, 2006, 11:50 AM
I'm working on a pretty agressive "lean cruise" alternative tune, but have noticed that spending any time at idle means:
1) my AFR of 15.25 for my idle cells is ignored and the truck goes to 14.6-14.7
2) spending any time at idle or in stop and go traffic destroys the gains from the aggressive fueling table (3647).

I mean when I'm sitting still and idling my instant mileage is 0!! :muahaha:

But seriously, I throw money out the window when I idle with these heads, cam and injectors (my average city mileage is 8.5 -- but it's real city -- 13-20 miles a day in 35mph zones and traffic). I've noticed that there is a open loop lean idle pid (B3607) but when I changed that to 15.5 to allow my custom table to kick in (I'm always in open loop), instead of 14.6-14.7, the truck ran at 13.5 AFR lol.

Also, my small pulse threshold (B4006) is 2.75ms and at idle, my pulsewidth is 2.4. Can I drop this threshold with impunity? For example, if I set this to 1.9 or so, will I see side-effects such as rough idling, etc.?

ChucksZ06
February 16th, 2006, 02:44 PM
I am not as far along as you but am attempting the same end result. It seems that no matter what I do the O2s keep me at 14.7. Changing the switching voltage up or down made no difference. I am wondering if there is a way to fool the pcm with modied o2 voltages?

oztracktuning
February 16th, 2006, 05:00 PM
What would the ideal compromize AFR be at idle to get good idle economy and not hurt the cats or the engine??

turboberserker
February 16th, 2006, 06:13 PM
I have no cats and have forged internals, so I am tryin 15.25-15.5 at idle.