I have a 2006 Ford Ranger with 2.3L 4-cylinder engine. It has been burning oil at the rate of about 1200 miles per quart. It has a bucking and misfiring action at very light throttle (cruising) between 1500-2000 rpm that seems like a leaky EGR valve. I replaced the valve, had leaky valve stem seals replaced, new spark plugs and the symptoms are the same. If I disconnect the EGR the engine runs fine, just get CEL illuminated.

I am getting suspicious of excess back pressure from the Catalytic Converter, it may still be early in a failure mode that other conditions don't yet show CEL codes(?) I think the excess back pressure pushes excess exhaust gas through the EGR valve.

I have replaced MAF, MAP, Throttle position sensor and coil pack.

Anyone have thoughts about this?

Thanks,

Kurt

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Kurt
Calhoun, Ga
2006 Ranger, 2.3L, 5 speed

If you suspect the cats are clogging then the passenger side floor would be hot as hell since the cat is directly under the floor.

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How's things in carpetland?

I'd check the DPFE hoses and DPFE for clogging. The exhaust gas on either side of an orifice is used to diddle the EGR flow. If the hoses or DPFE have clogged ports, it could be adding more EGR than it thinks based on measured pressures. Perhaps the DPFE itself?
If those things checked, I think I'd use a scan tool and watch to see if the EGR is being commanded ON when the misfire occurs. I'd also take a look at MAF for cleanliness of the two wires, and check fuel pressure & volume. A slight lean condition can cause grumpy running, and low pressure/volume could contribute. If the MAF was encumbered with schmutz, it would report incorrect air flowing in, and mislead the computer to feed incorrect fuel amount per volume of air.
tom

added: A quart of oil consumed or seeping out in 1200 miles is not really that bad. Some oil will get turned to vapor and fed through the PCV to the intake. Cannot be avoided. Check brand you use for vapor point? There is a term, but not in my available words at the moment.
tom

thirty seconds later: volatility

Whens the last time you replaces the pcv valve...

Thank you for your replies!

I had a valve job done last summer. All ports and the EGR tube were clear. The valve job made no difference in how it ran. PCV valve was replace with the valve job, Again, no cha he.

This is quickly becoming the worst vehicle Inever owned, at only 100K miles.

I use recommended Mobil 1 5W 20 oil, next oil change will be 5W30.

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Kurt
Calhoun, Ga
2006 Ranger, 2.3L, 5 speed

I think I would be pulling the COPs. The CoilOnPlug has a 'boot' at the bottom that encircles the spark plug, mostly the ceramic insulator. If the boot gets contaminated with oil because of leaking O-ring gaskets around the plug wells, the rubber/silicone/??? may get to the point that the spark can jump to the cylinder head instead of to the plug gap. The oil changes the boots so they seem to pass spark easier, leading to misfire 'whenever'.
One other thing, from description, would be to check that the MAF wires are clean. If the MAF has crud, it won't signal the computer of the proper amount of air being inhaled by the engine. The computer would provide fuel for X amount of air, while Y amount was there to be mixed and burned. If wrong enought, misfire can occur.
tom

Thanks again for your input.

This has coil packs, not COP's. I replaced the spark plugs and wires with new ones when reassembling the head on the engine. The bucking did not change with all that work I had done.

Also, I have cleaned, replaced and cleaned the MAF sensor, replaced TPS and MAP and EGR. Nothing has made any difference...

I'm not trying to be difficult, I am looking for help.

Thanks again!

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Kurt
Calhoun, Ga
2006 Ranger, 2.3L, 5 speed

Have you double-checked the configuration of your spark plugs and wires?

You could pull the O2 sensors for test purposes, replacing with a pressure gauge, to see if you have slightly excessive back pressure due to converter destruction. For that matter, you could pull the O2 pre-cat, and allow it to make noise to see if your engine smoothed out. Be sure the exhaust won't burn up the rest of the vehicle as it will be flame-like and HOT.
If you have replaced the DPFE with aftermarket, take a trip to a boneyard and find one of similar vintage that is factory. I understand that the Dorman brand may not be quite up to the task, and could be lying to the computer about the amount of EGR being applied. I have heard this about other brands, but not so much. Some say OEM only for DPFE due to repeat failure rate.
The DPFE measures pressure across a metering device(drilled washer) embedded in the EGR pipe. It has two hoses that can stand exhaust temps that connect, one to either side of the orifice. The pressure on one side will be different from the pressure on the other if the EGR is being applied. That difference is measured by the DPFE and reported to the computer. If it is lying, more or less EGR would be flowing than the computer was commanding. I think there may be a table of proper values(Hz or V) that the DPFE calculates and sends to the computer based upon the pressure difference measured.
If that measure was wrong, you could get too much/little EGR flow...
EGR should not be applied at idle rpms. If the EGR leaks, it could be supplying EGR when it was not supposed to...
tom

Thanks,

My next step is to run the vehicle with the front oxygen sensor removed to see if that makes a difference.

Thank you for the forethought that I must protect from hot exhaust gas coming from the hole in the pipe.

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Kurt
Calhoun, Ga
2006 Ranger, 2.3L, 5 speed