RE-SOLVED: Engine running way rich, 0V reading from all O2 sensors - BAD FUSE (1 Viewer)

Joined
Nov 4, 2007
Messages
10,198
Location
Colorado
Few more thoughts:

Coils still first thought, if well tuned engine.

Make sure all O2s in tight and not leaking passed the crush washers or gaskets.
No exhaust leaks engine heads to pre muffler
Consider a back pressure test on exhaust forward of CATS.
Make sure all grounds around engine (body, frame and engine) working attached and clean.
Make sure all battery post, clamps & cable in good condition (no oxidation) and run Volts around 14V
Do a vacuum test. Google for videos on how & what to look for as RPM raised.
Make sure EVAP vac line all good.
Seems I saw you did R&R spark plugs. How did coils and their boots look!
Check fuel dampening device for proper operating.
Consider FPR R&R, in rigs over 150K miles or in rigs that sit prolonged periods not started of refueled.
 

Eicca

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Apr 26, 2009
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I think I solved it again, for good this time. Replaced the EFI fuse. Not only are fuel trims back to normal, but the transmission suddenly feels noticeably and significantly snappier than it has in the entire four years I've owned this car.

More details here.
 
Joined
Nov 4, 2007
Messages
10,198
Location
Colorado
I think I solved it again, for good this time. Replaced the EFI fuse. Not only are fuel trims back to normal, but the transmission suddenly feels noticeably and significantly snappier than it has in the entire four years I've owned this car.

More details here.
I'd never guessed that from "Engine running way rich, 0V reading from all O2 sensors". I would keep a keen eye on the fuse box.
 
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Eicca

Professional Noob
Joined
Apr 26, 2009
Messages
2,346
Location
Utah
I'd never guessed that from "Engine running way rich, 0V reading from all O2 sensors".

If the transmission performance hadn't also been significantly improved, I'd still be doubting it myself.

Bad current causes computers to do wonky things though. All four sensors flatlining at once when hitting the gas was the clue that pointed me toward power delivery.

If the problem comes back, I'll replace the entire fuse/relay block and the EFI relay itself. The ECU is my last resort.
 

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