Thread: sort out fuel trims

Hi all,

Right now im running e85 on my stock injectors with a 3.5 pulley.

I have been trying to sort out the fuel trims, but it just doesnt seem to be working.

I unplugged my MAF and logged as suggested in the tunning for dummies how to.

I went into Airflow and primary VE and adjusted each of the values the log gave me. When the fuel trim was 5% i added 5% to value in the table. When the trim was negative, i subtracted 5%.

I went and logged today with the MAF plugged in and the LTFT seems like its even higher. Non of the values moved towards 0. I even parked, let the car idle and learn the idle LTFT values, went into the tune and added twice that amount to the table for those values, restarted and re logged and there was virtually no change. What am i doing wrong?

I changed my fuel filter, it was pretty stopped up about 2 tanks ago. Should i try that again? I did max my injectors on this log which has never happened before. Maybe the new filter is clogged? or maybe all of the gas is out of the car?

Some other details, the injector gain is set to 1.33

here is a link to the log file and tune, my WOT pull is pretty much at the end.

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first things first: plug that maf back in and don't bother tuning your ve. the ve is only a backup and doesn't have any bearing on how the car will run unless the maf fails.

edit: second: are you logging throttle percentage? you also need to be logging your O2 sensor. also, on the scan I downloaded, your maf table only shows one value, are you logging it right?

Originally Posted by SgtMarshal

first things first: plug that maf back in and don't bother tuning your ve. the ve is only a backup and doesn't have any bearing on how the car will run unless the maf fails.

edit: second: are you logging throttle percentage? you also need to be logging your O2 sensor. also, on the scan I downloaded, your maf table only shows one value, are you logging it right?

I used whatever the stock setup was for the VCM logger.

I will try and add the o2 sensor and the MAF table (i dont see one in the graph). I did see values change in the gauge area.

I have no idea if I am doing this right. Where do i adjust fuel then if not VE? Which table should I be working with?

ill set lower maf if need be with ltft. stock maf you dont always need to touch down low. but up top you may have to. ill do a scan and watch maf hurtz and what the wb says. if you pause the scan and use the arrow keys to move ahead its like a second a click of the button,

you need to set your pe afr to 1.200 and see where you land on the commanded, small amounts from there up or down with dial it in to where you want it, mid 11's.

set pe enable to like 30% hot. so now you know when you see 30% throttle you should be in pe mode commanding the lower afr. now watch the wb as the scan goes, you want the wb to match the commanded, so if its not matching you look at maf hurtz and the wb and raise to add fuel, lower to remove fuel to those cells.


i dialed my n* maf using this part of the scanner only pretty much.

Originally Posted by Scottydoggs

ill set lower maf if need be with ltft. stock maf you dont always need to touch down low. but up top you may have to. ill do a scan and watch maf hurtz and what the wb says. if you pause the scan and use the arrow keys to move ahead its like a second a click of the button,

you need to set your pe afr to 1.200 and see where you land on the commanded, small amounts from there up or down with dial it in to where you want it, mid 11's.

set pe enable to like 30% hot. so now you know when you see 30% throttle you should be in pe mode commanding the lower afr. now watch the wb as the scan goes, you want the wb to match the commanded, so if its not matching you look at maf hurtz and the wb and raise to add fuel, lower to remove fuel to those cells.


i dialed my n* maf using this part of the scanner only pretty much.

I don't have a wide band o2 yet. I'm just trying to get my fuel trims down to + or - 4

Guys, im sorry if i'm dense but what table should i be adjusting to increase or decrease fueling? Where do i Find the "MAF" table?

in airflow, then maf hrtz frequency

I think ive gotten the scan right ... Should be obvious which log file it is. I just ran the car for a few minutes to check.

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On another note:

I will be chaning my injectors to the Deka 80#. How do i go about doing that? i recall reading that i need KPA ... zzp says the following Static Flow Rate @ 43.5PSI ( 300kPa ) w/Gas: 80 lb/hr = 630 cc/min = 850 cc/min Is that useful at all?

I found the Flow vs KPA table, should i just enter 80? looks like the values change a bit based on pressure, should i just divide 80/33 and multiply the figures in the table by that?

I have read that the idle with the 80s can be difficult on pump gas because they are so large, anyone else hear of this?

I am installing all of my mods tomorrow. I have read that you can run a lot richer with e85 without loosing power, to help with cooling the charge etc. what table would i change to tell the car to run a bit richer? I would like to start out rich, and inch it back towards stock just for safety.

you dont want to be richer. set pe to 11.5, watch the wb to make sure its reading the same, if its not you add to the maf.

Originally Posted by rickisrad

How imperative is it to log trims without disabling the Power Enrich? Asking for a friend.

What do you even mean? I mean, can you clarify what you are trying to do? If you have no PE enabled, definitely dont take it over 7000ish hz. Are you trying to tune with narrowband?