LTFT low, LTFT mid and LTFT High are all giving me values of 0.1 and nothing changes during cruise, wot and idle?

Any help with diagnosing the issue would be helpful, I would really like to see what is going here.

I do get valid values for everything else, STFT works fine but no other fuel trims change at all during logs.

TIA

 

did you drive the car? go on highway and cruise for a good 12 minutes and if they still dont move then something is wrong.

 

Yup, I drove to work a couple days ago logging the entire way - it was about 25 minutes. Nothing moved during the entire log, 0.1 the whole time?

 

make sure that your rear O2 sensor is enabled. I know that on the 8's you need to have the rear O2 sensor enabled in order to properly log fuel trims.

If you start getting the p0142, then you know the rear O2 is enabled, then you should be able to start logging trims.

Also try logging the O2 sensor voltages. Make sure that you are getting some readings. If not, then you may have a dying front O2 sensor.

Josh, if you want some help contact me offline and we can work out a trade.

fender rolling for some diagnostics and fuel trim tuning??

 

I think I should be able to work this out, thanks for the offer chris. Fender rolling can be arranged, but it cost $... I'll give you the autox'ers discount

The cause might be because I have disabled the rear o2 sensor then?

 

I know on my 8 that the disabled rear O2 can cause this.

Also keep track of how long it takes the front O2 sensor to respond on the first cold start of the day. If it takes longer than your wideband, then chances are the front O2 sensor is dying.

Also, a failing front O2 sensor will also cause the fuel trims to wander which ultimately causes lean and/or rich conditions at the wrong time.

 

My wideband responds almost immediately. My front o2 always takes longer. So my front o2 is bad?

 

IF the front o2 is bad it will throw a code. If its not throwing a code and you dont have the CEL disabled via periphery bit then its good.

 

and yes this is correct. However the funny thing is, the Trims come from the front o2. But if the rear o2 is disabled, nothing works. Rear o2 is a bull**** sensor for reading oxygen that passes the cat. basically just a sensor to keep track of how well the cat is doing its job, although some cars have other purposes for this sensor as well.

 

Thanks for confirming that, I will enable the rear o2 sensor and see if I can get the trims to log.

 

pretty much the 2nd O2 just turns on the CEL light for a converter failure
but thanks for the info in this thread! I've been wondering why the hell I cant get my fuel trims!

 

Old thread but related question. My fuel trims are all 0 and don't move. My rear o2 sensor is disabled, because I don't have one. I have an Evo V with an Evo VIII ECU. Any idea how I would go about getting my fuel trims to log?

 

Evo life is much easier when you run JDM ROMs, no rear o2 sensor to screw you around.

 

Weld a bung into you DP/exhaust for a sensor and then wire it into you ECU correct pin.

 

I like the idea of using a JDM ROM... but I also like using Tephra V7.

There's no easier way? The rear o2 doesn't even effect the fuel trims.