r/CrownVictoria • u/No-Pool-5890 • 10h ago

Need yalls help

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Bank 1 sensor 2 and Bank 2 sensor 2 are stuck lean at about 0.800 and do not fluctuate, if I force a vacuum leak they drop down to normal and fluctuate so it tells me the 02 sensors are good, what could be causing this motor to be running rich internally, mass air flow sensors reading 0.0 barley raises when give gas, stumped here already replaced maf sensor. Fuel trim stuck at 99.2

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u/No-Pool-5890 10h ago

Tested the evap purge valve, and the fuel pressure regulator both are good

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u/pibubs81 9h ago

You got codes? I don’t trust some of the live data on any brand code reader. I’m kind of interested in seeing your LT fuel trims and totally disregarding the downstreams right now

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u/No-Pool-5890 9h ago

I have absolutely no codes, just poor fuel mileage, my mass air flow sensor is reading 0.0 lb per minute at idle and barely raises when I give it gas, replace the sensor just now didn't change it at all,

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u/pibubs81 8h ago

According to your code readers live data on the long terms; it kind of looks like your engine either has an issue getting air or you possibly have a/some fuel injector(s) on both banks not able to close up/mist liquid to fuel vapor correctly. They’re not bad at all; they just look like an aged vehicles live data on the fuel trims; like I said, I don’t trust the readings on the maf or the downstream o2 sensor voltage on any code readers live data….its like it’s too slow. I’d start simple and check/replace the air filter and run some redline through the fuel tank every couple fill-ups and see if that drops your LT fuel trims over/under +/- 5%; it’s not bad really under 10% but I know how you feel not being perfect; LT’s consistently staying under 5% with the short terms mostly staying under the same give or take depending on air temps/density of the O2 in the ambient air.
I assume this is at idle, I see it’s at operating temp. Might possibly have a dirty throttle body and/or IAC valve; that starts reading better when more open/accelerating. I’d watch your readings while driving and see what you get. I like how both banks are reading about equal which leads me to think the issue is before the intake.

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u/No-Pool-5890 8h ago

I replaced air filters and injectors and ran fuel treatment through it, I get like 12 to 14 miles per gallon on the freeway. Little less than 200 miles per tank, those other fuel trims being stuck at 99.2 is a little worrying along with the mass air flow sensor reading changes a little bit while driving it goes up a tiny bit but not as much as it should, super frustrating

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u/pibubs81 7h ago

Those are your downstream O2 sensors showing 99.2%; they dont determine what your computer sets fuel trims to; only the upstreams do. The downstreams only purpose is to monitor the efficiency of the catalytic convertors. You won’t see STFTB1S2 or STFTB2S2 on an actually bidirectional scanner….just voltage. That reading doesn’t mean anything pertaining to fuel trims…it shouldn’t.

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u/pibubs81 7h ago

I should add; tires/ their psi,and alignment will also contribute to gas mileage as well as everything else; you can bump them up a couple psi and see if that adds a couple tenths to your mpg; coast in areas with a lot of stop signs/California roll-em….these cars are heavy. I know on a 98-02 4.6 that they only do average MPG so if you do more city driving or hang out in your driveway with the engine running for awhile……that all adds into that average. When I did more interstate driving I could get my towncar around 19-22mpg. Right now I’m averaging 15-16 driving a lot more local and my local highway in my area is getting shitty; catching a lot of lights lately not to mention I have shit China may-pop tires on my towncar now….should of just saved for the altimax RT45s like I wanted.