new to OFT and ecu tuning. Help with trims

[derka-derka]

hi guys,
just started looking into trims after getting my OFT last week.
my trims seems weird.

http://www.datazap.me/u/derka-derka/...0&data=1-10-11

Currently runing:
OFT Stage 2 EL
Catted EL headers
hiflow cat FP
blitz catback
perrin 2.75 cai

why are my stft all over the place.
Previosly running stage 1 and my LTFT were crazy negative high. somwhere like -14. its usually 0 when 3000rpm+, then decel or under 2k rpm would got to -14 ltft

im hearing he 2.75 perrin dsnt need scaling

ideas?

[D_Thissen]

From what I have read, STFT can be all over the place. It has to do with Ethanol content/IAT/Load/RPM etc and the LTFT learns from that. @steve99 might be able to help you out with more. He seems very knowledgable.


I copied this from one of his threads.
"Fuel Trim Learning
To speed up learning of fuel trims you will need to drive smoothly. The ECU only learns fuel trims in “Closed loop “ mode this is during slow or steady throttle movements and cruise and idle. When your driving aggressively on/off throttle and wide open throttle the ECU is in “open loop” fueling mode and does not learn fuel trims, it just applies the fuel trims learned in “closed loop” fueling mode. If the ECU has not had enough learning time in closed loop it will apply incorrect fuel trims and car may feel sluggish or hesitant till it learns.

If your MAF has been scaled correctly hence reducing fuel trims to less than around 2% this learning process is very quick or not needed. Even with stock intake components the MAF scaling can be out by around 8% in places if individual MAF scaling has not been done, more if you have changed intakes and not re-scaled MAF.

Vishnu Reset -Trick
Yes you can google it :-)

Basically it speed's learning of Fuel Trims and will Reset you IAM to 1 if it has dropped due previous knock events (assuming its not knocking at low/steady loads if so you have serious knock problems).

If you do 2 or 3 "vishnu reset" runs ie partial light (20% or so) steady throttle runs from 2000-5000rpm or so in 3rd it will set your fuel trims and reset your IAM (assuming is not knocking at low/steady loads) if its less than 1. The gear is not really important its the partial steady throttle the longer the run the better. A slight uphill grade can be useful (or you can left foot brake). This works anytime to reset IAM back to 1 (assuming its not knocking at light load) it useful when your chasing knock in an area and want IAM back to 1 without an ECU reset."


Maybe you could reflash the stock rom, then go back to your current one? Again, I would wait to see what @steve99 has to say. I am still learning as well lol.

[KoolBRZ]

Originally Posted by derka-derka

hi guys,
just started looking into trims after getting my OFT last week.
my trims seems weird.

http://www.datazap.me/u/derka-derka/...0&data=1-10-11

Currently runing:
OFT Stage 2 EL
Catted EL headers
hiflow cat FP
blitz catback
perrin 2.75 cai

why are my stft all over the place.
Previosly running stage 1 and my LTFT were crazy negative high. somwhere like -14. its usually 0 when 3000rpm+, then decel or under 2k rpm would got to -14 ltft

im hearing he 2.75 perrin dsnt need scaling

ideas?

Attached is a revised MAF scale for the Perrin 2.75" Intake. I would recommend starting with this scale, then use vishnu's speed learning method to stabilize your scaling, then correct with @vgi's utility. Don't be afraid to ask what you need to know, it helps if you search first, some of the people here will rip you a new one if you ask about something that has already been covered extensively. I've attached the Perrin MAF scaling and the mafmaster utility that I use for scaling. The A/T's have load limit issues which interfere with consistent MAF scaling, @Wayno has created some excellent xml definition files and ROM tunes which address this issue, in addition to creating a fuel-efficient E85 tunes. I recommend reading @Wayno's OFT maps, E85 etc. here http://www.ft86club.com/forums/showthread.php?t=83945 . I have the Skunk2 intake and couldn't get a MAF scale to stay trimmed. I also highly recommend the PLM/Nameless long-tube header for more low-end torque for the automatic's.

[steve99]

As @KoolBRZ said looks like maf scaling needed.

just check for any exhaust or intake leaks first.

The Perrin 2.75 intake can be run without scaling but you will get better results with scaling. the perrin supplied scaling is ok but doing your own scaling is best.

Fuel trims are the ecu attempt to compensate for maf scaling errors, ethanol content and temperature variations. LTFT is the average of short term fuel trim over time.

High LTFT (over 5% or so) usually indicate need for maf scaling or an intake/exhaust leak.

see maf scaling link below

[derka-derka]

thanks guys for info..now ive got to learn how to use VGI program to scale maf. trying to search up a guide. no idea how that program works yet
tried to open log file but keeps saying invalid file

[steve99]

Originally Posted by derka-derka

thanks guys for info..now ive got to learn how to use VGI program to scale maf. trying to search up a guide. no idea how that program works yet
tried to open log file but keeps saying invalid file

their is a help guide in the vgi program

with OFT logs remove the first 3 lines I think the stuff like "Prodeede log"

just leave the headers in like throttle,maf,rpm ect but remove stuff above that then vgi utility will read it

[derka-derka]

maanged to get the perrin maf figures KoolBRZ linked to my rom. flashed it and it seems a bit better now.
STFT and LTFT are close to 0 during acceleration and WOT. LTFT only goes to high negatives (-10) during idle or decelartion down to <2krpm

[KoolBRZ]

Originally Posted by derka-derka

maanged to get the perrin maf figures KoolBRZ linked to my rom. flashed it and it seems a bit better now.
STFT and LTFT are close to 0 during acceleration and WOT. LTFT only goes to high negatives (-10) during idle or decelartion down to <2krpm

Give it a week, then tell me LTFT is still at zero. I've seen so many tunes start out so well, only to settle into higher trims over time. I think that slightly higher, (positive) trims drive nicer, peppier, and yet get better mileage in town. Highway mileage though, you want those trims to be right at zero for highway cruising to get the best mileage.

I use the older mafmaster utility by vgi. I download my logs from my OFT, then open in excell and remove the top 3 lines, close, saving as .csv files. Open mafmaster, open RomRaider, copy MAF scaling table from latest ROM file, paste into closed loop tab first, import logs, click "go" on the right, then "chart" on the left, click the "current" radio button, (because I like to see how much is being changed compared to the current scale), then copy scale at the bottom and click on the "open loop" tab at the top, paste the scale in there, import WOT logs, click "go", copy that scale, and paste into RomRaider and save as newest tune. You only have to set the settings and import the open loop table once, it remembers after that.

[wparsons]

It takes a lot of drive cycles for STFT to move into LTFT, that's why they'll shift over time. If the scaling calculation is working corectly (the VGI one does) it doesn't need the LTFT's to be stable since it also looks at AFR requested compared to actual AFR.