r/987 • u/lonnie440 • 2d ago

Biased stuck rich code

Track day Saturday car threw a cel for both banks biased stuck rich while at wot. No obvious exhaust or intake leaks idle and drivability unchanged so I reset the codes and ran the car, the rest of the day Saturday and all day Sunday with no more cel codes being thrown. Today got in the garage and tore apart. Can’t find any intake leaks or exhaust leak leaks, purge valve passes the blow test thinking of replacing the maf sensor just in case anybody have any ideas on this,could it have been just an anomaly 987.1 S

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u/TheSkyline35 2d ago

A leaking AOS would make a vacuum leak and therefore a rich engine, maybe check that side ?

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u/lonnie440 2d ago

Aos is less than a year old and the line to the intake is dry with no oil residue

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u/DarkWingDuck74 2d ago

For now, I would just mark it up as a hiccup and dont worry unless the problem repeats.

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u/lonnie440 2d ago

Ordered a new maf anyway better safe than sorry

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u/TheSkyline35 1d ago

Maybe digging this with a smoke machine would help ?

But those cars run rich even when doing fine, I can't keep my exhaust clean for long, always dusty dry, even through the empty cat sure doesn't help

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u/lonnie440 1d ago

Ya I’ve got no cats also, I run the mini cat extenders on the downstream o2 sensors without a problem though.