Flex Fuel Inferred To High Problem
flex fuel inferred setting at 70% fuel trims lean at idle +15 give or take. …cleared kam and drove until flex fuel learned after each step ….…cleaned MAF (MAF is at 2.75 at warm idle seems a little low not ready to pull trigger on that yet though) cleaned throttle plate. fixed small vacume leak marginally improved fuel trims. tested fuel pressure setting at about 53 psi spec supposedly 51 to 60 psi. Tried jumping fuel pump module to run pump wide open worsened fuel trims more lean (possible poor connection drooping voltage didnt have gauge attached at the time). AF senors seem to to respond well doubt both are bad problem affects both banks. isolated PCV and brake booster vacuum no change any suggestions thanks guys.
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.
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.
problem solved thanks for the suggestions ended up being the MAF after all i knew that reading of 2.75 at idle was low. I was just a little gun shy should have trusted the numbers. Most of you may know this but for those who dont a rule of thump for the MAF is the grams per sec should roughly equal the engine displacement in liters so if you have a 3.7l engine your MAF grams per second at warm…