advise on where to start correcting tune issues
05-16-2013, 07:25 AM
#21
The VE table is a measurement of airflow, so is MAF frequency, they are not direct fueling tables. The pcm uses these values and multiplies them with the expected afr ratio amongst other things to set base fueling. Then, when in closed loop, adjusts fuel with STFT and LTFT to get to stoich.
With what I have read about the subject, your first step in tuning a new combination is to input a good estimate of what the target afr should be with the fuel you will be using. Most say that E10 should be at 14.1 afr but most pumps give between 5% and 8% ethanol, and a good starting point is 14.3 or 14.4 target afr. Using these values, your fuel trims should be closer to zero to start off with and would require less tuning.
I believe it's another one of those things that can make tuning easier or faster, but you can still get a good tune without adjusting it.
As the others have mentioned, the wideband needs to be adjusted for the fuel you are using, or you need to tune in lambda for it to be accurate.
With what I have read about the subject, your first step in tuning a new combination is to input a good estimate of what the target afr should be with the fuel you will be using. Most say that E10 should be at 14.1 afr but most pumps give between 5% and 8% ethanol, and a good starting point is 14.3 or 14.4 target afr. Using these values, your fuel trims should be closer to zero to start off with and would require less tuning.
I believe it's another one of those things that can make tuning easier or faster, but you can still get a good tune without adjusting it.
As the others have mentioned, the wideband needs to be adjusted for the fuel you are using, or you need to tune in lambda for it to be accurate.
05-16-2013, 12:51 PM
#23
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ok, i went back to the 14.4 to be safe then as i have no idea exactly how "safe" the tune is in other places.
cam is comp xer273hr-14 it specs at 224/230 @.050 .581/.588 lift 114LSA says it has very aggressive lobes. i like it, it runs good now that the o2's are working. i think i've lost a little power some where, but i will find it as i work my way through HPT.
cam is comp xer273hr-14 it specs at 224/230 @.050 .581/.588 lift 114LSA says it has very aggressive lobes. i like it, it runs good now that the o2's are working. i think i've lost a little power some where, but i will find it as i work my way through HPT.
