Open Loop Fueling Changes Over Time

[Exley]

I was wondering if anyone had some experience with if/how the 2005-2010 Mustangs carried their long term fuel adjustments into WOT. I've been having trouble with my 2007 3v 4.6 Mustang where the air fuel in open loop will progressively get richer or leaner over time. If I disconnect the battery or flash the car, it will go back to what I was originally targeting.

I would rather not disable LTFT all together. The only things I have seen to adjust were "Fuel WOT Adaptive" Which was already disabled in my stock tune and "Learning MAX TPS" witch I changed from 100% to 60% but didn't see any change. Any help is really appreciated.

Attached is my current tune. 93Oct_20.hpt

Edited post to try a make a little more sence. Was frustrated when I posted the first time

[Exley]

Ok to follow up a little bit. I did some logging today. Both positive and negative fuel trims do seem to be applied to WOT. For now I turned off my LTFTs. Does anyone know of a way to keep Long Term Fuel Trims from being applied to open loop? I've read about being able to do it on the older ford PCMs

[Eric@HPTuners]

Ok to follow up a little bit. I did some logging today. Both positive and negative fuel trims do seem to be applied to WOT. For now I turned off my LTFTs. Does anyone know of a way to keep Long Term Fuel Trims from being applied to open loop? I've read about being able to do it on the older ford PCMs

Are you seeing LTFT correction at WOT on the scanner? If so, post the logs and tune file.

[Exley]

Yes. My tune is attached. Sorry I didn't save the log. I had a histogram plotting LTFT over MAF. It looked like it grabbed the last cell before I went into Open loop. For example -4.5% and that would be plotted accross the rest of the MAF table while at WOT. during the pull my air fuel was about that far off as well. As soon as I flashed the car my fueling was dead on again. Sorry I don't have a log. I'll work on getting one

[Exley]

I found an older log that shows it. if you go to frame 3127 I do a pull. It looks like it's adding 5.1% This log wasn't with the posted tune but it illustrates what i am talking about.

log2.hpl

[Exley]

Bump. Any useful information in that log? If not I can turn LTFT back on and post another log once they populate.

[Exley]

Wanted to bump this up for conversation again. I've installed a Whipple ford racing kit on my car and am experiencing the same symptoms again. Had a solid .78 lambda through WOT pulls. This is what I am commanding in my Open Loop fuel table. It has started to get progressively leaner. Saw .83 on a pull yesterday. I will try to get another log to verify. I have attached my current tune.

[caniggia]

I wrote this in another thread. 05 Mustangs are wrong from factory in this case, it's related to intake temp and fuel pressure vs temp. V6 are much more crazy than GT in this case.
The more heat, the leaner it goes up to 20% lean. Then when you start cold you are 20% to rich because ltft were learned.
To cure this problem air temp sensor must be installed in the intake or fuel vs temp compensation disabled (all cels filled with same value), both method works on GT, but only first works on v6 or pressure compensation vs temp should be more adjusted, but then it goes out of range.

[Exley]

I wrote this in another thread. 05 Mustangs are wrong from factory in this case, it's related to intake temp and fuel pressure vs temp. V6 are much more crazy than GT in this case.
The more heat, the leaner it goes up to 20% lean. Then when you start cold you are 20% to rich because ltft were learned.
To cure this problem air temp sensor must be installed in the intake or fuel vs temp compensation disabled (all cels filled with same value), both method works on GT, but only first works on v6 or pressure compensation vs temp should be more adjusted, but then it goes out of range.

Just to specify this isn't over the course of a few pulls with the car heat soaking. It is over a period of a few weeks or a month as the LTFTs settle.

[ZeroAviation]

Can you post up your logs?

-Matt