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.

What's the scoop?

 

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.

 

Thanks for the response!

I just got off the phone with my favored mechanic, and he said the fuel issue is BS!

He suspects either a vacuum leak or possibly a fault in one of the O2 sensors.

I gotta take it over to him so he can diagnose the problem.

He concurred that high ETOH will not throw a 'lean' code.

 

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.

Jim

 

J&M,

Thanks!

Yah, the truck is starting and running 'normally', so whatever the issue, it must not be too serious.

And I don't need to worry about high revs. I don't think my sweetie has ever had the engine past 3500 rpm.

I'll post the findings...

 

The mechanic just called.

Apparently the problem is a common one. The PCV elbow on the back of the intake manifold had deteriorated and cracked.

He's pretty sure that is the problem, but he will call me when he checks the car afterward.

Here is an interesting thread on the subject from OBD-II Trouble Codes - DTC Codes Car Repair

- 97 Ford Expedition codes P0171 and P0174 not a PCV leak - OBD-Codes.com

 

Well, I was gonna 'edit', but don't see how...

Anyhow, the problem was indeed a cracked elbow. However, the elbow is no longer available by itself; Ford is now selling a PCV hose assembly for a bit over $30.

So, ethanol had little, if nothing to do with the problem.

 

well thats good to know, there are problems that could happen because of the ethanol, gummed up stuff.

good to know it wasnt you

 

of course it is no longer available