LTFT's keeping going up?

[ms6acton]

so ive been monitoring my LTFTs with my dashahwk for the past month or so.
when i started they were at 0.0-0.8% then 0.0-1.8%, 1.8-2.3% and now they are at 2.3-4.7%

the lower number being when im off throttle-accelerating.
i dont have any engine mods. any idea why they could be going up like they are?

 

[LBV]

The temperature outside can have an affect but I've only seen that when it's very cold. Have you checked all of the clamps on your intake tract to ensure they're tight, especially the the one right at the turbo?

 

[ms6acton]

no i havent.. ill check them all today when i get home from work

 

[tunersteve]

If you can, log it with throttle position and post it up.

From what I've read (not sure if this is 100% accurate) anything +-5% is alright, even +-10% isn't awful. Ultimately, the closer to zero you are, you're better off.

On mine, I see anywhere from -1% to +5% on the LTFTs, depending on throttle position.

 

[ms6acton]

ill do some logs later and post em up.
i just thought it was strange since they started at 0 and are gradually going up even tho i have no mods

 

[bova80]

the general saying by cobb is as long as you are withing +/-8% you are ok.

you won't throw a CEL until they are +/-20% or so.

the weather will have an affect on your fuel trims and also the way you are driving too. i know my fuel trims have been changing little by little even after 400+ miles of driving on this map.

 

[ms6acton]

the general saying by cobb is as long as you are withing +/-8% you are ok.

you won't throw a CEL until they are +/-20% or so.

the weather will have an affect on your fuel trims and also the way you are driving too. i know my fuel trims have been changing little by little even after 400+ miles of driving on this map.

okay cool
i guess ill just keep watching them and making sure they dont go up too high

thanks

 

[Atreyu3388]

Sorry to thread jack...

I hooked up my DashHawk for the first time today and my LTFTs are through the roof compared to some of what I've read on here...all I have is a Full Length Intake right now. They were ranging from between 11.7%(Cruising/Idle) to 15.6% (WOT). I'm kinda worried since I know most peoples are MUCH lower than this. I am reading them from Bank 1 too, I don't know if that has anything to do with it. Also it's about 34 degrees today, but I have a SRI so I wouldn't think that would have too much to do with it. Any help is appreciated...

 

[ms6acton]

so today my LTFTs are back to 0.0-1.6. i didnt change anything or add something. maybe pressure change or temp getting warmer, i dont kno? either way im happy theyre back down. just thought i would let u guys kno

 

[MShreve]

Is the LTFT value a moving average? Meaning that the value just reflects the difference from the current average.

If so, then I would expect the number to fluctuate quite a bit if you drove it hard one week and then took it easy the next, or visa versa. Which means you'd have to drive it exactly the same way under the same conditions all the time to keep it close to the 0 mark.

Assuming the above is true, then it's really a number that you shouldn't worry about unless it gets out of control (+/- 20), right?

 

[ms6acton]

i dont think its an average. its a constant number. its your engine adjusting

 

[tunersteve]

+-10% is the acceptable value according to Cobb. Think of your LTFT as a trend line for a data set. The STFT would be the value of the data, and the LTFT would be a best fit line for it. It moves, but only in response to repeated data.

 

[rawr123456]

"Fuel trim refers to adjustments being made dynamically to the base fuel table to get the proper ratio of fuel to air. Short term fuel trim refers to adjustments being made in response to temporary conditions. Long term fuel trim is used to compensate for issues that seem to be present over a much longer period. Fuel trims are expressed in percentages; positive values indicate lean (add fuel) and negative values indicate rich (subtract fuel). Fuel trim banks refer to the cylinder banks in a V style engine. Cylinder #1 is always in bank 1. Fuel trim is generally calculated by using a wide set of data values, including front O2 sensors, intake air temperature/pressure (or the more elegent air mass sensor), engine (coolant) temp, anti-knock sensors, engine load, throttle position (and change in throttle position), and even battery voltage can effect fuel trim. Long term fuel trim generally should not exceed +- 10%." - Taken from http://www.obd2crazy.com/techdata.html

 

[ms6acton]

i kinda kne some of that but its nice to fully understand. good info, thanks!

 

[MShreve]

My LTFT's are all over the chart. I can actually watch the value go from 10.x% to 5.x% back to 10.x% in just a matter of minutes while driving normally.

I've double and triple checked my CAI connections and BPV connections and everything's tight with no apparent leaks...those are the only engine mods I have so far. What else could cause such erratic LTFT's?

 

[LBV]

When was the last time you cleaned your CAI and IAT/MAF sensors? That might help.

 

[Qwik6]

When was the last time you cleaned your CAI and IAT/MAF sensors? That might help.

Mine used to go up to 10.9% often. Cleaned the maf sensor last week and running the stage 2 map now. LTFT's stay from 0-3% now under all conditions. Just an overall smoother feel.