weird ltft issue

[articzap]

Car is a turbo lsj with blow thru maf. Narrow band and wide band sensors less then a year old.

From a hot start, the car will show +5 ltft on average. After about 15 minutes of driving, ltft make a subtle swing towards -6 on average. This makes it damn near impossible to tune the maf. With fuel trims off, the wideband shows the same trend of lean to rich given enough time.

What are somethings to check and look at?

[cobaltssoverbooster]

first are you starting your recording directly after start up?
if answer is yes, you need to drive the car some first to garuntee your recording is in closed loop. then you may find this is a bit different.

[Iam Broke]

Intake tract air leaks if the above post doesn't help. Wait until it's warmed up before you start logging.

[articzap]

Intake tract air leaks if the above post doesn't help. Wait until it's warmed up before you start logging.

These are fully warmed up restart, but I'll wait longer.

[06cobaltss/sc]

Do you have any logs you can show us? If you don't have a large enough sample than things can appear skewed when they are not. For example if you only have say 5 hits in a certain cell it could be off a lot, while the cell that was hit 500 times is only off by 1%.

If that didn't make sense to you what I am trying to say is to log for an extended period of time. When I first start my logs, especially if I am stopped when I start them, the logs will show I am off by 5% give or take and then several mins later everything reads zero's =D

[articzap]

Do you have any logs you can show us? If you don't have a large enough sample than things can appear skewed when they are not. For example if you only have say 5 hits in a certain cell it could be off a lot, while the cell that was hit 500 times is only off by 1%.

If that didn't make sense to you what I am trying to say is to log for an extended period of time. When I first start my logs, especially if I am stopped when I start them, the logs will show I am off by 5% give or take and then several mins later everything reads zero's =D

I usually log until I see over 500 count in the cells I'm trying to tune. I think the issue is just trying to start log to early.

[cobaltssoverbooster]

everytime you turn the car on it has a open loop cycle even if its warm already. obviously when warm already it doesnt stay there as long but like i said the few mile drive garuntees its closed loop

['09SS]

drive 100miles for the tune to settle in before making changes otherwise you may be chasing your tail.

[cobaltssoverbooster]

well he does that by changing only the cells that have had over 500 hits