My Fuel Trim Low Readings...

[4G63dsmpwr]

Hey while I'm driving I noticed the following happens a lot w/my logger: I'll be driving around and everything and my fuel trim low will be around 81% or something like that and then all of a sudden it will increase all the up until like 118% (it goes 81, 82, 83, 84, all the way up to 118). I don't think this is normal, does anyone know why it might be doing this? And what happens if this isn't corrected/and what does this actually mean? My mid and high trims are both good (I think?) and are usually between 80-83%. Thanks, Erick

 

[turbolover2]

80% means the car is running a little rich. What other values change when the fuel trim changes? What other conditions (RPM, speed, etc.) change when the fuel trim changes?

Read about fuel trims here:

http://www.vfaq.com/TMO/

and here:

http://www.vfaq.com/TMO/Tuning-Tips.htm

 

[pneumo]

That sounds like the way a 1G hacked MAF will act when the throttle is at very small openings, like when the airflow is about 100 Hz or less. Mine does that, too. Either that or a sporatic air/ boost leak.

 

[4G63dsmpwr]

I have an extremely hacked MAF so maybe that is the cause of the problem? I don't know what other conditions change when the Fuel Trim Low starts to increase (I will check and post back ASAP) but I do know that a few times (not sure if ALL the time) its happened while I'm idling. And running at 118% is that going to hurt anything? Ok well thanks for the help, Erick

 

[jw]

If you do a search on this forum, you will find a few posts I've made on the conditions of fuel trims changing.

Running at 118% is not going to hurt because it's within the ECU *window*. The highest it can go for long term trims is 139% and the O2 short term will range from 30-167.