Why am I getting positive LTFTs in PE cells?
06-21-2016, 03:16 PM
#1
Why am I getting positive LTFTs in PE cells? I had my truck on a dyno at power tour and had the opportunity to scan and log the runs. After the first run, I uploaded a tune with 2° more timing because I knew timing was conservative, but they didn't give me time to adjust the VE table so I didn't even look at it.
After getting home and looking at the runs, both were rich compared to my tuning logs, mid 11afr vs mid 12 afr. I looked a little further and see that it logged +4 LTFT in the PE cells. I have never seen this before, generally they stay zero. I just imagine that is what is causing the rich condition.
I will have to check my PE enable parameters, but I think they are pretty much stock 02 Camaro stuff.
Anyone have any idea the cause?
This is a 6.0 6 speed with 0411 pcm running 02 Camaro tune as a base.
After getting home and looking at the runs, both were rich compared to my tuning logs, mid 11afr vs mid 12 afr. I looked a little further and see that it logged +4 LTFT in the PE cells. I have never seen this before, generally they stay zero. I just imagine that is what is causing the rich condition.
I will have to check my PE enable parameters, but I think they are pretty much stock 02 Camaro stuff.
Anyone have any idea the cause?
This is a 6.0 6 speed with 0411 pcm running 02 Camaro tune as a base.
Last edited by Bowtie316; 06-23-2016 at 08:08 AM.
06-21-2016, 09:02 PM
#2
Here is the tune and log if anyone cares,
dyno 2.hpl
Studebaker 6.0 6spd wideband VE tuning REV13 CLOSED LOOP ENABELED +2 degrees timing.hpt
dyno 2.hpl
Studebaker 6.0 6spd wideband VE tuning REV13 CLOSED LOOP ENABELED +2 degrees timing.hpt
06-23-2016, 04:02 PM
#4
I just read this on another forum, could it be true?
tblu92-Remember---If you have a Negative LTFT number (rich) just before going to WOT the trims will lock on "0"--However if you have a Positive LTFT number(lean) just before going to WOT it will lock on that number-adding that % amount of fuel to your WOT fuel ratio.That is why it is always best to get the LTFT's either "0" or slightlt negative.
tblu92-Remember---If you have a Negative LTFT number (rich) just before going to WOT the trims will lock on "0"--However if you have a Positive LTFT number(lean) just before going to WOT it will lock on that number-adding that % amount of fuel to your WOT fuel ratio.That is why it is always best to get the LTFT's either "0" or slightlt negative.
06-23-2016, 04:20 PM
#5
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I just read this on another forum, could it be true? tblu92-Remember---If you have a Negative LTFT number (rich) just before going to WOT the trims will lock on "0"--However if you have a Positive LTFT number(lean) just before going to WOT it will lock on that number-adding that % amount of fuel to your WOT fuel ratio.That is why it is always best to get the LTFT's either "0" or slightlt negative.
06-24-2016, 07:04 AM
#7
Okay so just to clarify, it could pick up the fuel trim from the last cell it was in prior to going into PE and carry that through even if there is no fuel trims in the PE cells?
If that's the case I will just go back through the VE table and make sure all the trims are a little negative.
If that's the case I will just go back through the VE table and make sure all the trims are a little negative.
