LTFT Pulling fuel even while Lean and difference in bank 1/2

[[email protected]]

Hey everyone,

I've looked all over the forum and google for an answer to this question but cant seem to find it anywhere, so if its a repost I apologize.

I'm running MAF only closed loop, have a wideband but am mostly using the LTFT's to gauge how close my tune is to being correct. I am consistently running 1.04 (approx) lambda, but my LTFT's are pulling 2-4% fuel.

I'm also adding fuel to one bank and pulling from another in some cases.

My questions are:
1. Do LTFT's always pull fuel to create a lean condition?
2. Is there a way to adjust the target AFR so I wouldn't pull so much fuel?
3. Is the difference between LTFT's in Bank 1/2 normal?

June 11 log.hpl
Tune for LTFT questions.hpt
original.hpt

[gtstorey]

Making a different thread for each question or step in the tuning process just causes confusion and doesn't allow people to build on and follow up on previous advice.

[Cringer]

Hey everyone,

I've looked all over the forum and google for an answer to this question but cant seem to find it anywhere, so if its a repost I apologize.

I'm running MAF only closed loop, have a wideband but am mostly using the LTFT's to gauge how close my tune is to being correct. I am consistently running 1.04 (approx) lambda, but my LTFT's are pulling 2-4% fuel.

I'm also adding fuel to one bank and pulling from another in some cases.

My questions are:
1. Do LTFT's always pull fuel to create a lean condition?
2. Is there a way to adjust the target AFR so I wouldn't pull so much fuel?
3. Is the difference between LTFT's in Bank 1/2 normal?

June 11 log.hpl
Tune for LTFT questions.hpt
original.hpt

1. Do LTFT's always pull fuel to create a lean condition?
One viewpoint of LTFT, is that their job is to keep the short terms at 0%. This means long terms may be negative, positive, or zero to achieve that goal.

2. Is there a way to adjust the target AFR so I wouldn't pull so much fuel?
Yes there are a few things you can do here, but don't. Don't focus on if they are pulling fuel. Rather you need to tune your MAF and VVE. Most people want the fuel trims to be slightly negative so they err on the side of rich.

3. Is the difference between LTFT's in Bank 1/2 normal?
There will always be a few percent difference, that is normal.

FYI You would probably be better off disabling LTFT and running STFT only.

[Alvin]

Hey everyone,

I've looked all over the forum and google for an answer to this question but cant seem to find it anywhere, so if its a repost I apologize.

I'm running MAF only closed loop, have a wideband but am mostly using the LTFT's to gauge how close my tune is to being correct. I am consistently running 1.04 (approx) lambda, but my LTFT's are pulling 2-4% fuel.

I'm also adding fuel to one bank and pulling from another in some cases.

My questions are:
1. Do LTFT's always pull fuel to create a lean condition?
2. Is there a way to adjust the target AFR so I wouldn't pull so much fuel?
3. Is the difference between LTFT's in Bank 1/2 normal?

June 11 log.hpl
Tune for LTFT questions.hpt
original.hpt

The fuel trims are meant to swing lean. This is so there is left over oxygen to burn off stuff in the cat. There is no o2 left in a stoich mix. So the average of it swing from Stoich to lean for the cats averages bit lean on your wideband. This isn't a problem. Completely normal.