Flex Fuel Inferred To High Problem

Flex fuel inferred is essentially a third tier to fuel trim. short term is immediate, Long term learns as we go and now the PCM, mostly after refueling, will check for newly lean fuel trims and assume its due to ethanol. First verify what is in the tank. Ethanol can be tested with the water separation method, expect about 10% Inspect for anything related to lean engine. low fuel pressure (fuse…

Buy the Rev X ethanol tester off Amazon for $12 and be done with it. Water and fuel fill lines, along with ethanol percentage are all there. Cheap/fast/effective.

Chris Thanks for telling us about the Rev X. For years I've used the Kohler TESTER -Alcohol content # 25 455 11-S I got my from Jack's small engine, but it is probably available from your local small engine repair. The Rev X (which you have suggested) seems more complete with the scale on the side.

I failed to mention original post I did test for ethanol there was none present e85 is not common at all where I live. I did also check for a leaky purge valve thanks for the reply. I also checked the fuel pump fuse 27 the update had already been done. Like I mentioned in my original post I also checked fuel pressure with a gauge and would be hard-pressed to believe that I had a problem with the…

I would check the evap purge solenoid for leaking when closed. When the fuel is cold (winter) it doesn't evaporate and the stuck open purge solenoid will put the fuel trims lean because it is basically pulling air in like a vacuum leak. This will also make the m.a.f. read low which it is for the engine displacement (should be around 3.7 to 4 GPS at 600 rpm)

In my continuing education here with you all-I suggest a weak fuel pump.

I had a probelm on 2012 Ford F-150 5.0 hard start when cold and elevated fuel trim found a canister purge valve leaking at all times . Reset fuel trim and run fine fuel trim all normal.

Do you have any rear o2 fuel Trim bias?

Just went through one of these recently on an Taurus and found the purge to be leaking. I was able to block the purge line and instantly see a change in short term trims.

I had similar issue of the flex fuel monitor was high when flex fuel was never used with a Chevy HHR and I reset the Flex fuel monitor and all the fuel trims became normal and the cold startup was no longer an issue as well. That might just as well solve the cat codes as well because how the cats are monitored.

Unfortunately Ford wasn't gracious enough to offer the reset like GM did. You instead have to reset keep alive memory and drive for extended periods.

Really!! That stinks. I thought that all vehicles that had E85 were required to have monitor resets for this particular situations.

Ethanol stoichometric is 9:1 however this system compensates timing & fuel calculations I dont know .If sensorless using O2's sounds like PCM isnt adjusting injector PWM ?

If flex fuel inferred sets at 70% while you have regular gas in the tank, your fuel trims should be rich as ethanol contains less energy than gasoline. The pcm programming would account for that by injecting more fuel than needed. Guess you have more air leaks or fuel delivery issues. I would put a ½ tank of fresh gas, do hard pcm reset and run the vehicle to see if flex fuel learn adjusts down.

Possibly dirty/clogged injectors.

Excellant!! Glad you solved it.