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Lean code, Random Multiple Misfires

NotMyExplorer2006

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April 18, 2019
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Year, Model & Trim Level
2006 Explorer 4.0 V6 XLT
Hi all...Im helping repair my sister-n-law's 2006 Explorer XLT 4.0 sohc v6. Its got "running lean" code and "random multiple misfire" code. Ive replaced the ignition "coil/box", intake o-rings, fuel filter, plugs and wires. It starts up just fine (when cold), then upon warming up, starts dieseling and dies when brought to a stop (rpm's drop to 3-400). Also after warming up, smoke/burning oil from driver's side valve cover gasket. Please point me in the right direction...she's driving me nuts at this point. (The sister-n-law, not the Explorer)
 






Rcflyer330

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March 23, 2014
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City, State
Michigan
Year, Model & Trim Level
2010 Ford Explorer XLT V6
Could be fuel filter or o2 sensor. Whats the code?
 






CharlieK9

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July 25, 2016
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City, State
GREENCASTLE, PA
Year, Model & Trim Level
2010 Explorer XLT
With a lean condition, probably detected by the front O2 Sensor means the air fuel ratio has too much air for the amount of fuel being injected. There is air entering the engine that the computer does not know about, as in a vacuum leak or air intake leak. The Mass Airflow Sensor is responsible for measuring the air and reporting it to the computer.
Check for clean air filter
Check for vacuum leaks - listen closely, or spray water on the hoses to seal up the leak. There are other methods.
Clean the Mass Airflow Sensor (many videos on the internet)
If absolutely sure there are no leaks and that there is sufficient
fuel to the injectors, then you can begin to think about sensors.

Any type of scan tool that can read fuel trims will be very useful.

Good luck,
 






NotMyExplorer2006

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April 18, 2019
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Year, Model & Trim Level
2006 Explorer 4.0 V6 XLT
Air filter clean. Fuel pressure good....It still stalls after getting up to running temp. I have already replaced plugs and wires, fuel filter, intake o-rings, pcv valve. The idle is erratic after warming up and it starts "oil"-smoking after getting warm (but only on the drivers side)
 






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