Fuel trim malfunction?

[AWDGUY86]

Hi, I have had my check engine light on for a little while now but it doesnt seemto affect drivabilty. Well now that I hooked up the OBDII scanner, it says for dtc (codes) there is a fuel trim malfuntion. (P0170) However I looked in my manuel and I cant find that code it like completely skips over it to lik p0169-p0171. Any one have a input?

 

[Staytuned]

It is lean condition in bank 1. And it can be caused by any number of things. Do a search on here, I know that it has been mentioned before.

 

[gs-t spidey]

This same thing happened to me some time ago. It ended up being my o2 sensor. so you should start with that. You can get a generic one that you wire up yourself for like $50 at an auto store or you can go to mitsubishi and get the factory part which cost about $120. One question for you. How does you car behave it idle, partial throttle and full throttle.

 

[AWDGUY86]

hmm some times it idels a little rough during start up every so aften, seems slower then when I bought it, and it ticks a little bit under hard throttle for the the first 30 secs after started then goes away. I really apreciate you guys helpin me cuz I could not find the code for Sh*t.

 

[AWDGUY86]

so i replaced my o2 sensor and that didnt do anything but set me back a couple hours of work and more ideas?

 

[akdsmer]

Now that you've thrown a part or two at it, you need to diagnose it.

You said you have a scan tool? Can it read the generic OBDII data? If you got that, the rest will be pretty easy.

Fuel trim is the amount of fuel that is being added or subtracted by the PCM based on inputs from the sensors. The computer is programmed to add certain levels of fuel (injector on-time) based on the sensor input. If after the programmed amount is added, and the O2 sensor sees it it lean or rich, the computer compensates by adding more or less fuel. (adding injector on-time or shortning injector on-time) That is fuel trim-the correction of fuel delivery as determined by the O2 sensor as compared to the factory programmed values.

Fuel trim issues can go either way...rich or lean. With generic data you can see what the problem is and start addressing it. Until you know rich or lean, you'll be just throwing parts at it. (although the O2 sensor is usually the culprit).

Let us know what scan tool info you have and we'll take it from there.

 

[spyderturbo98]

well, i had that code also but i finally made it go away. it was my air hose coming from my BOV going to the throttle body. it has a cut so it was leaking air...

 

[nkhende]

I pulled this code, and was wondering if it could be caused by venting to the ATM? I know that causes it to run rich, and was wondering if that's ever triggered this code before. BTW, don't flame for venting, I bought the car used and I'm working on venting back to the intake.

 

[AWDGUY86]

So this a long ago post but i still have this problem, the car acts like it has fuel cut/ fowl spark plugs were under heavy acccel it feels like fuel cut almost. I almost think its the tps sensor but then again the code thrown would normally say somthin like tps sensor below threshold. Maybe it has to do with the mas? im so confused it hurts. But with the new o2 sensor in the car and it not helpin at all, and me not being able to actually diagnose the problem, its driving me up a wall.