Running rich HELP!

[anthonymtz]

Hey all, hope everyone is doing well, i have a 04' 4.6 explorer that I recently noticed that bogs down while idling, just small hick ups every 20 seconds or so, second thing i noticed is my exhaust smells rich, i hooked up a scanner and have no codes, checked live data and my fuel trims from what I've been researching are high, one bank is 18% and the other bank 12.5% these are the LTFT readings the STFT readings on both at idle are around -1.6% to 3% im adding a picture of what the scanner showed, its just a $20 basic one but it works. I've tried looking for a vacuum leak with carb cleaner but everything passed, no misfire while driving runs good it just burns fuel, I've also cleaned the throttle body, MAF sensor and even tried leaving the battery off for a few hours and nothing, tired running few cleaners through as well, i have a lot of black soot around my exhaust if that also helps, and inputs are welcome and appreciate!

 

[J_C]

Positive fuel trim is a sign it is running too lean so ECM adding that % of fuel trying to compensate.

Just to rule it out, I'd check fuel pressure, though I'd suspect that to make it worse under load. If that's okay, I'd look for signs of a misfire even if not frequent enough to set a code, since you report smelling it in the exhaust. You might notice one of the spark plugs looks wet/cleaned for example, or as far as the possibility of too much air in the mix, try to find a vac leak using a smoke test, since you've already cleaned the MAF sensor.

Since it is happening at idle, I'd also wonder about the IAC, idle air control valve. Is it possible that these idle RPM dropouts only occur when the A/C compressor tries to cycle on? That's how I first noticed my IAC needed attention but that was on a '98 4.0L. Anyway if you turn the climate control off, that should remove the A/C cycling variable. IAC can stick and sometimes cleaning it out helps, or other times the wear is enough that it needs replaced. I like to put a drop of oil on the shaft in them at the shaft bearing/bushing and let that run down into the bushing for a few hours prior to reinstalling.

 

[anthonymtz]

Positive fuel trim is a sign it is running too lean so ECM adding that % of fuel trying to compensate.

Just to rule it out, I'd check fuel pressure, though I'd suspect that to make it worse under load. If that's okay, I'd look for signs of a misfire even if not frequent enough to set a code, since you report smelling it in the exhaust. You might notice one of the spark plugs looks wet/cleaned for example, or as far as the possibility of too much air in the mix, try to find a vac leak using a smoke test, since you've already cleaned the MAF sensor.

Since it is happening at idle, I'd also wonder about the IAC, idle air control valve. Is it possible that these idle RPM dropouts only occur when the A/C compressor tries to cycle on? That's how I first noticed my IAC needed attention but that was on a '98 4.0L. Anyway if you turn the climate control off, that should remove the A/C cycling variable. IAC can stick and sometimes cleaning it out helps, or other times the wear is enough that it needs replaced. I like to put a drop of oil on the shaft in them at the shaft bearing/bushing and let that run down into the bushing for a few hours prior to reinstalling.

Thanks so much man! It's been raining so I'll try to get to it as soon as it dries up I didn't notice I don't feel the car bogged down when my AC is on, since every time I turn the AC on I see the idle pick up and it'll stay steady, but when it is acting up most of the time the AC is off and it is just idling, I go WOT frequently and have no issues with misfiring or cutting out in the high RPMs so im thinking the IAC, another thing is I was getting a code for a evap leak if I'm not mistaken, but I was just wondering if the EVAP system runs on vacuum, if it does I'd be suspect that would be the reason it's running weird, again thank you so much you giving me somewhere to start I really appreciate it!

 

[J_C]

Yes the EVAP system runs on vac and a leak there could account for it running lean. Just to rule out the easy thing first, make sure that your gas cap makes a seal. Otherwise, if you don't see a broken line, you can plug it off along its route to see if that changes the fuel trim numbers, then the leak was after where you plugged it (though lack of vac may still trigger a pressure sensor error), or smoke test it for leaks.

 

[anthonymtz]

Yes the EVAP system runs on vac and a leak there could account for it running lean. Just to rule out the easy thing first, make sure that your gas cap makes a seal. Otherwise, if you don't see a broken line, you can plug it off along its route to see if that changes the fuel trim numbers, then the leak was after where you plugged it (though lack of vac may still trigger a pressure sensor error), or smoke test

it for leaks.

Yes the EVAP system runs on vac and a leak there could account for it running lean. Just to rule out the easy thing first, make sure that your gas cap makes a seal. Otherwise, if you don't see a broken line, you can plug it off along its route to see if that changes the fuel trim numbers, then the leak was after where you plugged it (though lack of vac may still trigger a pressure sensor error), or smoke test it for leaks.

Okay, i got the new IAC today just didn't get a chance to put it on, i did find out there is a fuel leak of some sort on the gas tank, i had smelled a strong odor of fuel and looked under at my tank and there was a wet spot running down the side of it, looks like the tank will have to dropped, not looking forward to it. :/