My wife called me (of course, these things always happen when I cannot respond) and told me the CEL came on in her '97 Expy (5.4L).
I directed her to Autozone. She called, saying the code was a 'Lean Condition, both banks'.
She puts the Autozonian on the phone. He says he's seen a bunch of cars lately with the same problem. His 'solution' is to put a 'heavy' dose of either Gum-out or Lucas engine treatment in the fuel tank.
It seems to me that getting some fresh (and hopefully 'better') fuel in the tank would be the more appropriate fix.
I have not seen the light come on for lean fuel with high ethanol content, just an emission code. Lean condition would indicate possible fuel filter problems to me first. Unless you have put E85, I don't see any issue from just ethanol. If it were that simple, I should see it on a regular basis with just my family's vehicles, but do not. We even put in higher amounts, and as I stated, it comes out with a code from the cat converter being out of spec. That is an 02 Buick on e85... I am running 35% in a 91 Cavalier right now with no issues. Yes, it dropped 2 mpg, but that is a far cry from the 30% some claim, which would be 9 mpg on that car.
the workhorse:86 F250 4x4 6.9 Diesel 4-spd, 4.10 axles
the other workhorse 92 F350 2wd crew cab,3.55 rear axle, 92 6bt Cummins, NV4500
the project: 78 F150 4x4 shortbed 351 auto Iowa Chapter leader, ASE certified parts specialist
Come on down and join us in the Iowa chapter, or your own local chapter!! Thanks, Roger
If it is not flex-fuel, the injector sizes, that is the maximum flow rating, may not be enough to avoid leaning out too much with more than ten percent ethanol. No amount of additive is going to correct that. "Both banks" tells us that it is the pre-cat sensors that are involved, so the cat is out of the picture here. Usually a plugged fuel filter will have obvious driveability issues, as in reduced power at full throttle.
A vacuum leak is always possible. If the pipe between the MAF and throttle body has any leakage, that will throw things off a bit, but I thought the job of the pre-cat O2 sensors was to detect minor mixture faults and tell the computer to adjust. Throwing new sensors at a problem may or may not find it, but is relatively cheap.
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