General Low Fuel Trim stuck at 140%

[jackalopeTsi]

I am new to tuning, i fixed my logger cable the other day and logged a couple runs on my way home from work. My low fuel trim is maxxed out at 139.8%, i have read this can be a sign that your o2 sensor is going bad? i dont know how old it is, so i will probably change it when i do my next oil change. I reset my ecu, and set everything back to 100% also, but it took maybe 5 to 10 minutes for the low fuel trim to get back to 139.
and
Are fuel trims only used at part throttle? or are they used at WOT?

i cant do much with tuning now, but im getting my gm maft setup soon and i think im gonna sell my tial 38 setup to buy some injectors. its not creeping as bad as i thought it was.

 

[v8s_are_slow]

I am new to tuning, i fixed my logger cable the other day and logged a couple runs on my way home from work. My low fuel trim is maxxed out at 139.8%, i have read this can be a sign that your o2 sensor is going bad? i dont know how old it is, so i will probably change it when i do my next oil change. I reset my ecu, and set everything back to 100% also, but it took maybe 5 to 10 minutes for the low fuel trim to get back to 139.
and
Are fuel trims only used at part throttle? or are they used at WOT?

i cant do much with tuning now, but im getting my gm maft setup soon and i think im gonna sell my tial 38 setup to buy some injectors. its not creeping as bad as i thought it was.

richen the low trim. when you do so, watch your O2 trim. it'll cycle around 100 when you have the low trim setting around where it's suppose to be. then after awhile the low trim will eventually come down. make sure you're in the airflow range for low trim (SLOW!). O2's are WOT. trims are part throtttle....cruising. mid and high's take awhile to adjust. low is fairly quick.

also too.....
http://www.pocketlogger.com/index.php?pid=1gtech_trims

 

[spyderturbo007]

FT's are not used by the ECU at WOT, only during cruise/idle.

If your logger is working, check out your O2 sensor voltage (bank 1) at idle. You should see a voltage fluctuation between 0.20V and 0.90V (or close to that range).

According to your profile, you are still on the stock injectors so your afc setting should be at zero. If that is the case and your FT's are maxed, you probably have a shot front O2 sensor.

Let us know what you find!

 

[jackalopeTsi]

i dont have anything to tune with as of now, i have a maft on the way. my o2 voltage fluctuates around .10 and .85. i am on stock injectors, and i only have one o2 sensor(1g).
my low fuel trim is maxxed, and mid and high are rising a little, does this mean my o2 is shot?

 

[v8s_are_slow]

i dont have anything to tune with as of now, i have a maft on the way. my o2 voltage fluctuates around .10 and .85. i am on stock injectors, and i only have one o2 sensor(1g).
my low fuel trim is maxxed, and mid and high are rising a little, does this mean my o2 is shot?

not necessarily. i've had my low's max before while just sitting at idle (although i have control over mine) and the mids and lows be okay. i've seen guys with a stock ecu, stock injectors, etc. running 120% trims across the board. if the o2 was fluctuating slowly or barely, i'd say it's on it's way out. once you can adjust your trims with the maft, you'll be better off.

also too, you have to be going pretty slow to even be in the low trim range. about as soon as you stomp on the gas you're out of it. i wouldn't fret over it too much. what do your O2's look like at WOT anyway?

 

[timloomis]

it will adjust out with your maft.i used my maft to richen it 15% just for the low trim,which was 139%.my 3" exhaust made it lean out that much.

 

[jackalopeTsi]

i think i need to adjust my throttle cable, cuz i have to mash the throttle to the floor to get even 99.6% on my TPS, but its not going bad cuz at idle its at 10%, but my o2's are around .87 .89, a little lean i think, im running 14lbs of boost with my evo3 creeping to 16lbs by 6000rpms, and im getting some knock starting at like 5500 rpms. i need to get my fuel pump in and change my fuel filter(my uncle blew his turbo diesel cause of a clogged fuel filter, so im paranoid about that now)

i just checked my logs and my o2 voltage doesnt move at idle, thought it did, but it does when cruising. new o2 sensor?

 

[spyderturbo007]

i just checked my logs and my o2 voltage doesnt move at idle, thought it did, but it does when cruising. new o2 sensor?

So the voltage fluctuates while cruising and not at idle. Wow, that's weird. Every time I have seen logs with a bad O2 sensor you see an O2 that reads <0.10V all the time, or one that is very slow to respond.

Was the car warmed up while you were checking the voltage at idle? The O2 sensor needs to heat up before it will start to cycle.

How old is the O2 sensor? If it is a couple years old, you may want to replace it as routine maintenance, but I can't tell you for sure that it is bad.

 

[v8s_are_slow]

if it is bad, you oughta go ahead and try and fork out some money for a wideband if you can afford it. just one less mod you'd have to worry about later. plus, if you have pocketlogger, they already have the parameter for wideband so you wouldn't have to buy a display. i can't speak for mmcd but i'd assume they would have it as well.

when my O2 went bad, it wasn't doing anything at idle. it'd cycle while cruising but got pretty slow. but yeah, you need to have the car warmed up before the O2 sensor starts giving a readout anyway.

 

[jackalopeTsi]

i dont hav it with me right now, but i pretty sure it was warmed up, i had driven about 10 minutes to get some food at Sonic, waiting for my food i saw it was not moving, it stayed arounnd .03v i believe. i just quit my job to go to school, so i dont have money for a wideband, and the car will have to wait till i find a nother job, for more major mods, but this small stuff i will fix now.

i dont know if it cycles or not while cruising, but it does move around quite a bit.

 

[v8s_are_slow]

warmed up at idle and cruising, it should cycle up and down. sometimes if it's an autometer, the lights will go off when at idle. maybe come on and cycle every now and then. but will usually cycle.

decelerating, won't cycle. won't do anything. lights will go off.

wot, it'll stay around a certain range and stay there or flicker around a certain area.

 

[TalonJohn94]

FT's are not used by the ECU at WOT, only during cruise/idle.

If your logger is working, check out your O2 sensor voltage (bank 1) at idle. You should see a voltage fluctuation between 0.20V and 0.90V (or close to that range).

According to your profile, you are still on the stock injectors so your afc setting should be at zero. If that is the case and your FT's are maxed, you probably have a shot front O2 sensor .

Let us know what you find!

- Car is a 1g, If it matters.

 

[v8s_are_slow]

nope, it doesn't