[seanm5005]

Looking for some direction. I have checked for vacuum leaks, I even went as far as disconnecting the main vacuum line from the intake manifold and plugging it. Spraying down the upper, lower intakes. No change in engine RPM. Drove around with a fuel pressure gauge positioned against the windshield. When connected to vacuum I had 29 PSI at idle, with load only 35 PSI. With vacuum line disconnected on FPR 38 PSI. I have an ELM 327 and while monitoring sensors in real time, bank 2 long term fuel trim is not lower than +19? It is staying mostly +21 to +25? Short term fuel trim on bank 1 and 2, are toggling between -3 to +8. I have cleaned the MAF with brake cleaner.

I just replaced fuel filter, and the car has new fuel injectors.

[jrowledge]

What is your long term fuel trim on bank 1. If it is not in the twenty range I might look for a faulty injector(new is not always good), a weak o2 sensor on bank two, etc. If the fuel trim on bank one is + or - 5-10% think of what could affect just bank two.

[seanm5005]

The long term fuel trim on bank 1 is +18 to +21, just not as high as bank 2. What should the O2 sensors read, or better yet, what should I be looking for to confirm if they need replaced? I hate replacing parts without troubleshooting first.

Thank You

[seanm5005]

Replaced all four O2 sensors. Car is running much better, I can see the short and long term switching like it should. Drove car around for a few short trips and everything appeared to be fixed. Then the following day same duration of driving and code 171 and 174 come on? Now what should I try? At one point before it coded the car almost died, and then it coded. I did not have my computer monitoring the car at that time.

Recap of the following has been done:
New injectors
New Fuel Filter
New O2 Sensors
Replaced old vacuum lines in engine compartment all the way to vapor cannister
Fuel pressure 28-32 PSI and 40 PSI with vacuum line disconnected
Checked intake for vacuum leaks. None

Sean

[shinerstang]

Check your EGR and DPFE sensor. A bad MAF sensor could be the culprit......

[seanm5005]

Are there any ballpark numbers I should be looking for when monitoring these sensors?

Thanks for the help.

Sean

[97stang3.8]

i think brake cleaner is way too harsh for a MAF

[seanm5005]

i think brake cleaner is way too harsh for a MAF
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1997 Blurple V6


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