Question about positive LTFTs at WOT

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Apr 20, 2005 | 10:49 PM

Another_User

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Question about positive LTFTs at WOT

Is there a specific set of qualifications that allows positive fuel trims at WOT? And is there some way to just eliminate positive trims in PE without forcing your trims negative?

Apr 20, 2005 | 10:55 PM

txhorns281

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From: Houston, TX

Quote:

Originally Posted by Another_User

Is there a specific set of qualifications that allows positive fuel trims at WOT? And is there some way to just eliminate positive trims in PE without forcing your trims negative?

Very good question...

Like, how does positive trimming in PE mode come to be? Do the O2s provide some kind of feedback after all? Or is there another reason this is allowed?

Apr 21, 2005 | 01:09 AM

luv2spd

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From: Newton, KS

I've always thought that you'll get positive trims in pe if you had a positive ltrim right before entering pe mode. Usually happens in ftc 15.

Apr 21, 2005 | 08:13 AM

Another_User

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Quote:

Originally Posted by luv2spd

I've always thought that you'll get positive trims in pe if you had a positive ltrim right before entering pe mode. Usually happens in ftc 15.

I have seen a lot of logs, but I don't think that is the case. I have a feeling there is something that can be adjusted for this. Hopefully something in HPTuners 2.0!!! I don't think I have ever seen a PE trim that matched the previous before PE. There has to be some sort of calculation, or limit before it adds the LTFTs.

Apr 21, 2005 | 08:22 AM

P Mack

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From: Phoenix

That's what i thought too, that it was the cell you're in when you transition to wot. What i'm really wondering is where the ftc 20 fuel trims come from?

Apr 21, 2005 | 02:17 PM

Silverhawk_02TA

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I'm not entirely sure what the exact set of qualifications are. I've only gotten positive LTFT's during PE when my other LTFT's are significantly positive as well. What I've read about the subject seems to suggest that if the PCM has learned LTFT's that are significantly positive, it adds fuel during PE as a safety measure. The only way I know of to definitely stop it (aside from getting the rest of your trims in line) is to turn off LTFT's.

Apr 21, 2005 | 02:21 PM

HumpinSS

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From: Waldorf, MD

Positive trims at WOT is the computer saying hey I know we were this far off before WOT so I am gonna add this on top of the commanded PE value just to be safe. There is no o2 feedback from the computer to come up with this value. It just uses the last known value from the PT loop for WOT fueling if your trims are +