How long does it take For fuel trims to move?

[91 TSi GP]

As the title states, my car seems to be running decent. Wideband is 13-15 cruising idles mid 14's but my fuel trims are not updating. I just drove the car a half hour and nothing moved.

 

[viperlp01]

Well if your front o2 sensor is locked in your FT will not change. Your STFT should change constantly with the sin wave of your o2 sensor. LTFT takes time to change. Log Combined FT on LINK

 

[the_mork]

I believe that LTFTs update every 6 minutes on an evo8 ecu. I have no reason to believe that this update cycle is any different for 1gs.

If your LTFT is not updating then you may have an issue with your o2 sensor, or a situation that is keeping you from sustaining closed loop.

 

[viperlp01]

I guess the main question to ask here.. Is your front o2 cycling? YOur car updates the fuel trims based off front o2 readings. If it is cycling then your in closed loop

 

[91 TSi GP]

Its cycling yes.

 

[the_mork]

Then you may not be hitting closed loop. You say you are idling at mid 14s, does it appear that the car is attempting to maintain 14.7? Or does it just kind of hold steady in the mid 14 range.

 

[91 TSi GP]

Then you may not be hitting closed loop. You say you are idling at mid 14s, does it appear that the car is attempting to maintain 14.7? Or does it just kind of hold steady in the mid 14 range.

it bounces around between 14's and 15's

 

[Ceddy]

The 2Gs and Evos take ~4 min per Fuel Trim cycle. And you need 4 cycles to max a Trim out. So you need to wait 16 minutes.

The 1Gs are a little faster I believe, but if you wait 15-20 minutes you should be fine.

If your Trims are not updating, one of you sensors may be out of range.
1G Trim info here -> fueltrimupdatepoints [ECMTuning - wiki]

 

[91 TSi GP]

Since their not moving and stuck at 100%, could I just go off my knock, timing, and wideband to tune this in?

 

[the_mork]

Absolutely, simply turn off closed loop entirely and then tune for AFRs. Use maptracer with relatively long logs and make small changes every time you drive. Pretty soon you'll get very close to the point where you'll feel like your chasing your own tail and that is the point where you stop tuning by deadtime and injector size (or VE tables if your tuning SD) and start making changes to your MAF comp tables or whatever your system has called them, and in the very end when you're very close you can make minute changes to fuel table for reach a real AFR instead of leaving the values as your desired AFR.