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Vacuum leak - P0171 - causing high LT Fuel Trim
Got a P0171 CEL the other day - lean condition in bank 1. Car idled a little rough and surged a bit but was fine under load while driving. I was hoping it was a dirty MAF but discovered a vacuum leak this morning. A hole in the PCV hose. Ordered a new part but have patched the whole with duct tape. Seems to have fixed the idle surge for now.
Which leads me to my next question. I'm using a OBDII tool with DashCommand and was watching the fuel trims. My STFT is steady at 0% no matter what. (is that normal?) My LTFT is sitting at 20% at idle and goes to 10% under load. Is that normal? Any other read out I should be looking at? CAT temps are around 1200 and go a bit higher at WOT.
I plan to check the fuel trims again after I replace the PCV hose, but just curious of these readings are normal or something I should be concerned about.
Current: 2004 Mazda 6S 3.0L Wagon | 2015 Mazda CX-5 | previous: 1990 Miata, 1992 Mazda MPV V6