long story short... blew the motor a year ago , now the car is back togeather , it idles a little high my a/f is at 12.5-13.5 when i give it gas or just crack the throttle it goes lean 16.0 then when the rev drops back to idle it shows 12.5-13.5 . it seems like it goes lean when you give it gas and let off the gas it goes rich, the car has not hd a battery in it till 2 weeks ago , check my sig for mods, i also have an o5 maf sensor with a mafia (set at 2)hooked to it, the car is tuned with the 05 meter and mafia on it with a blow thru setup on it ....my question is, is it possible to loose a tune if it hasnt been used in a year? or is my maf bad ? (blew motor on 9-14-09 if that helps) has new o2 sensors and no exhaust leaks
runnin rich at idle goes lean when given gas
- Thread starter blksq10psi
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sorry this is kinda long but i wanted to give evry1 asmuch info as poss. i also wanted to add why im asking this question, is that i know that the "slotstyle" maf sensor (05+) algra-rythm is backwards, from the "tonsil style" (2v) that my computer was tuned to OEM (now diablo chip with 05 maf tune) thats kinda why im asking if a tune can go stale? 
wmburns
SN Certified Technician
FWIIW, one symptom of a contaminated MAF is that it overstates air at idle and understates under low. This has the AF rich at idle to lean under load.
new MAF still the same result, the tune is on a diablo chip, 03 gt with a MAFia, vmp pigtail, with an 05 slot style MAF, is it possible to loose a tune on a chip like that, after sitting for a year? im only asking that question because i know the slot style MAF is backwards from the tonsil MAF (algra-rythm), so my thinking is that since my car is going lean when it should be giving fuel, somehow the tune went stale,
wmburns
SN Certified Technician
At the risk of stating the obvious, isn't it a little naive to think that reversing the air flow through a device designed for flow in one direction wouldn't adversely affect it's calibration? It seems logical to me that the error would be related to flow and at higher flow rates the error rate would be greater. Hence it matches your symptom of rich to lean.
This would give a transform that is difficult/impossible to correct for with a tune. The PCM is really expecting the MAF function to be linear. IE, twice the signal equals twice the mass of air. What you have is almost certainly non-linear.
This would give a transform that is difficult/impossible to correct for with a tune. The PCM is really expecting the MAF function to be linear. IE, twice the signal equals twice the mass of air. What you have is almost certainly non-linear.
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