fuel trims

[droppinbottom]

I have been reading over alot of posts concerning fuel trims and am a little confused. My settings on the afc II are lo throttle 30% and hi throttle 80%. My points are set at
1k, 2k, 3k, 3.4k, 3.8k, 4.2k, 4.6k, 5k, 5.4k, 5.8k, 6.4k, 7k. Currently I have everythig set at -7% across the board for the low throttle and I want to get my fuel trims as close as I can.

On my logger it shows my loft 81 midft 81 and hift 81. I read over the thread about how to adjust things but I am still unclear. What rpm range do I want to drive at to adjust for my low ft and around what rpm does it change over from low to mid? Sorry guys for the questions but I want to be able to learn and do this myself. I am not too worried about my WOT pulls as I have a lm-1 to help me adjust my hi throttle settings. Any help would be appreciated.

My current mods are
255lph(hig pressure)
afpr set at 38psi
fmic
lucas 550's
3" turbo back

 

[droppinbottom]

Wow no thoughts from anyone? Not even someone telling me to use the search button?

 

[ThunderValley]

Weather must be nice everyone is gone? Anyways, you are running rich with low fuel trims, you need to lean out the mixture a small amount at a time. It takes quite awhile of driving for the ecu to make any fuel trim changes. That is what I have run into with my 90 TSI anyways. Low FT is under 88hz, Mid FT is 88 to 188hz and HI FT is over 188hz. That is in airflow(hz). You can watch that on your data logger while you are driving to see the fuel trims change. I have had it take as long as 20+ miles for the trims to change.

 

[droppinbottom]

just a rough guess but the low fuel trims would probably be below 2k rpms and I should only be adjusting my 1k and 2k points to have a effect on low fuel trims? Would letting the car idle be a good way to try and adjust the low ft since driving that slow would be almost impossible for a extende period of time?

 

[BaddAssGst]

To add to this thread, the trims are not actually RPM dependable. The way I've always seen them is done by airflow (hz). Low fuel trims are anything from 0-125hz, mid fuel trims are 100-175hz, and high fuel trims are 175hz +. That is how you can determine which "range" you are in.

 

[droppinbottom]

Thanks for the help. Took about a 50 mile trip today and made alot of adjustments while driving and I have got the low trim at 97% mid trim at 94% and the high trim at 104%. This is about the best I could get things to adjust out evenly

 

[herostar]

-7% accross the board is not enough for 550cc injectors.

You should be tuning more in the -15% to -20% range.

 

[BaddAssGst]

Thanks for the help. Took about a 50 mile trip today and made alot of adjustments while driving and I have got the low trim at 97% mid trim at 94% and the high trim at 104%. This is about the best I could get things to adjust out evenly

Your a little rich at idle-ish and a little lean in your high trim. You could probably take out 1 or 2% of fuel (leaning) in your cruising range and add maybe 1-2% (richen) from 4500 and up to get it to zero. Your not bad at all, the closer to 100%, the better.

-7% accross the board is not enough for 550cc injectors.
You should be tuning more in the -15% to -20% range.

Yes and no. Alot of cars are different and may only require it leaned out 7% across the board. I didn't check his mod list but perhaps there is a hacked MAF, 2g maf, etc.

 

[droppinbottom]

Sorry guys -7% was not my final settings. I am at -10% @1k, -12% @2k, -13% on all the rest.

Currently on stock maf.