ThomasGS4

iTrader: (19)

I replaced the air filter about 2 months ago.

GS4_Fiend

iTrader: (22)

Hold up... Your fuel trims are reading positive bro.. how can your car be running rich? Hold the rev at 3000 rpms and re post up the STFT and LTFT again.

GS4_Fiend

iTrader: (22)

I disagree. Restricted air filter or inlet will not cause a rich condition on a MAF sensor vehicle. For a speed density system yes.

mitsuguy

iTrader: (2)

Unfortunately, it will... it would have to be pretty severely restricted, but it will most definitely cause this issue. It doesn't seem like it should, but it does. There are many cases documented in Identifix in which a restriction to the air intake system, before the MAF that caused system rich conditions... One of the reasons is throttle tip in fuel. Give the car some throttle, the ECU adds fuel ahead of time because it anticipates the added fuel need based on throttle position change, but, if the airflow doesn't keep up with what it was programmed for, then that extra fuel creates a rich condition...

mitsuguy

iTrader: (2)

I asked about this already - he never responded with a definitive answer if he just forgot the negatives in front, or if those were the actual readings, which, I agree, would be system lean, not rich...

GS4_Fiend

iTrader: (22)

On a MAF L-JET vehicle, if you got a plugged air filter, the PCM knows to compensate the fuel mixture. Therefore, you won't have a rich condition. Plus, he got a code for P0172. So, that's only one bank. In addition, the PCM watches the voltage on the MAF sensor, if the voltage is low, the PCM is not gonna be leaning the car out..It should increase pulse width on the injectors instead, which would be a lean condition not rice. Also it would only make sense if it was on a D-JET system because the MAP sensor senses high pressure. For one bank to be rich only. the possibilities could be plugged cat or bad oxygen sensor.

mitsuguy

iTrader: (2)

I didn't say that was specifically the issue, just an idea...

Again, you can assume what will or won't fix it, I'm just saying that in past similar issues, restricted intakes have caused this exact same issue... I don't have the proof for you in front of me, but monday at work, I will show you where it was documented that a severely restricted air filter caused this single code by itself on this exact same year make and model car. You can argue all you want, but sometimes issues don't always follow conventional logic. In theory, even, there is not much difference between a restricted cat and a restricted intake - as the MAF is still reading the amount of air and a restriction either place reduces airflow...

GS4_Fiend

iTrader: (22)

I do agree, theory doesn't always necessary means always right vs reality. But you do know this a forum discussion, so we could only base it on theory. But I do would like to see the document that you have mentioned if possible just for kicks. I am waiting on the data from Thomas.

ThomasGS4

iTrader: (19)

I hate to create such a controversy, but yes the results from the first test were indeed positive. I just went out and retested the car and here is what I received. Note that the car isn't fully warmed up.

STFT Bank 1: -3.9%
LTFT Bank 1: 0.7%

STFT Bank 2: -3.1%
LTFT Bank 1: 0.0%

Bank 1 Sensor 1 O2S Output: 0.040V
Bank 1 Sensor 1 STFT: 0.0%
Bank 1 Sensor 2 O2S Output: 0.045V
Bank 1 Sensor 2 STFT: 99.0%

Bank 2 Sensor 1 O2S Output: 0.805V
Bank 2 Sensor 1 STFT: 0.7%
Bank 2 Sensor 2 O2S Output: 0.115V
Bank 2 Sensor 2 STFT: 99.0%

mitsuguy

iTrader: (2)

Those numbers look good... the Sensor 2 fuel trims are erroneous though - there shouldn;t be fuel trims for those as they don't have any control, they are only there for monitoring the catalytic converters...

GS4_Fiend

iTrader: (22)

Not fully warmed up? What was the ECT reading? Are those fuel trims at 3000 rpms as I stated? Also, posting the oxygen sensor reading is not necessary. We can just look like the STFT and LTFT is good enough.

ThomasGS4

iTrader: (19)

ECT was 168 °F, and RPM was 746. I can try again here in a little bit once the car is fully warmed and at 3K RPM.

ThomasGS4

iTrader: (19)

Here we go:

ECT: 185 °F
RPM: 3,145

STFT Bank 1: -0.7%
LTFT Bank 1: -3.9%

STFT Bank 2: -3.9%
LTFT Bank 1: -2.3%

mitsuguy

iTrader: (2)

WIthin the range...

Maybe you had an injector issue and it cleared itself up?

GS4_Fiend

iTrader: (22)

Your car is no where near out of fuel control. Next time, when the CEL comes on, write down the freeze frame parameters. It will help a lot. Now quick question, does your car takes awhile for the ECT to get to normal operating temperature?