KOER code 41 lean... misses.. why?

[Wicked]

Ok, here goes: 91 ford explorer 4x4 5 speed

I don't know if this is coinsidental or not, but I ran two tanks of E85 through the explorer. First tank was great no issues, about 50 miles into the second tank, the engine started to miss . It misses at idle, misses under load, misses all the time.

I ran a scan and came up with no codes stored or anything, but under the KOER test, I came up with a code 41 runnign lean. I introduced some carb clean into the intake through the cruise control vacuum port and it smoothed right out.

So I am indeed running lean. I tested fuel pressure and its right where the book says its suppose to be.

Obviously I can't test volume and I have not checked amperage at the fuel pump when runnign to see if the pump is dying, but it turns on and sounds healthy for all thats worth.

The spark plug wires all ohm out perfectly, I put new spark plugs in it as well and gapeed them to spec.

I am going to replace the fuel filter, clean the mass air meter but beyond that any ideas what still could be causing the miss and lean condition?

[camaro1]

your vehicle is not a flex-fuel vehicle, it is not meant to run on e-85, e-85 will run very lean on a vehicle tuned for gasoline


to run e-85 you need to richen up your mixture, your vehicle is not meant to run on e-85, i have been running e-85 for a few weeks in my s-10 but i increased the jet diameter 30% to get it to run normal

since you have fuel injection you need to increase your injector pulse width, they make an adapter for e-85 that you plug your factory harness into then the box has a new harness to run to your injectors, there is a switch on it for regular gas or e-85, when switched to e-85 it will increase your injector pulse, you cant run a mixture of e-85 and gas,, only straight gas oe e-85 with this setup

[Wicked]

so do you think I burned up an 02 sensor ? The lugs looked REEEEEALY clean.. but also a little pink.

The truck acts just like its lean all the time now, even with a fresh full tank of 93. Not to mention the miss

[camaro1]

so do you think I burned up an 02 sensor ? The lugs looked REEEEEALY clean.. but also a little pink.

The truck acts just like its lean all the time now, even with a fresh full tank of 93. Not to mention the miss


maybe,, you might check compression and leakdown just to make sure it didnt burn a valve and that you still have a healthy engine

[gutlass454]

LOOK FOR a vaccuum leak.. spray out the mass air flow sensor with carb clean.. spray around the motor with carb clean to find your leak thats where the lean code comes from...

[BP Convt]

It could take 2 or 3 tanks of regular, 87 octane, gasoline to straighten out your long term fuel trim numbers. Also, ethanol also has a tendency to "clean" the fuel system. If you had a "dirty" fuel system before, maybe you dislodged some junk and plugged a fuel filter and/or injector to create a lean condition. Other than that, I'm clueless.

[Wicked]

I have a nice autoxray scanner that I am able to reset the long and short term fuel trim. It smoothed it out a little.

I did a compression test and I got 135-140 across the board. I am replacing the filter tomorrow. My very first thought was a clogged injector.