My Explorer seems to have a miss

[tman1257]

Just like the title says. But it is only when under a load, usually 1st or 2nd gear like if Im getting on it to pass someone. Regular cruising and driving I do not notice it. I have the 4.0 Sohc motor. Plugs have about 200 miles on them, wires I replaced about 35,000 miles ago. Fuel filter was replaced about 25,000 ago. I replaced the plugs thinking it would help but it seems to have come back. (original plugs replaced when I did the wires, so this is the 2nd set on it now.) Any way to tell if its the coil pack without having to get it scanned? I dont want to throw parts at it unless needed. Thanks all.

[homer302]

Not familiar with this motor. Does it just have 1 coil pack? If there are 2 (one for each bank) then you could find the dead cylinder, swap coil packs side to side and then see which cylinder is dead after that.
Obviously if there is only 1 coil pack, that is not possible.

Getting is scanned for a code is free pretty much anywhere so I am confused by your not wanting to get a code scan done.

[tman1257]

Single coil pack. I did scan it for free at a local parts store but no codes for a miss came up, just one for a small evap leak. That is what surprises me because you can feel it but no light. Im going through the wires and checking the resistance now to see if one of them crapped out. Anyone know what a good range is for the resistance on plug wires?

[MAD MIKE]

Does the stumbling happen at part throttle?
If so you may be experiencing an issue with EGR flow, and a lean misfire.

[tman1257]

Only when getting on it at almost full throttle or full throttle. Whats weird is that it idles smooth and at regular driving there is no problem. Gas mileage seems to be about the same also.

[jbiermann]

Maybe a fuel issue? When was the last time you changed the filter? Maybe enough flow for idle but not when you are laying into it...just my 2 cents

[jvaughan]

we get this stuff all the time at my work, probably related to the egr valve. otherwise just throw a coil pack on it if your worried about it, its a 15 minute job and they can be had for around 75 bucks

[tman1257]

Fuel filter has about 25k miles on it and is like 2.5 yrs old. Ill check into the egr valve. Might just put a coil on it and see.

[BLACK85GT]

When was the last time the MAF was cleaned?

[tman1257]

Havent cleaned the MAF but have had the intake tube off enough it shouldnt be too bad. Ill check that also.

[tman1257]

Well new coil pack and I can still feel it doing the same thing. It is weird because if I get on it, it really seems to pull like it should. Could the computer be telling the transfer case to kick in since it has the auto 4x4?

[MAD MIKE]

Well new coil pack and I can still feel it doing the same thing. It is weird because if I get on it, it really seems to pull like it should. Could the computer be telling the transfer case to kick in since it has the auto 4x4?

Did you check the EGR system?
Verify the valve is fully opening and if it does open verify that the ports are not clogged. Not just of the EGR valve itself, check the ports. If it has low flow it will cause a lean misfire. You can manually exercise the valve with your fingers, if it feels a bit crunchy when you manually pull it open then the valve may be full of carbon. Remove the vacuum tube, when you exercise it make sure there is no oil inside the diaphragm.

Spend the ~$8 in gaskets/O-rings/whatever to remove the EGR valve and feed tubes to verify that it is free of soot and carbon deposits.

[sideshow]

Check the Harmonic balancer I have replaced them for a loose counterweight
which can cause a "miss" What you need to do is stick your finger inside the center hole where the bolt is and feel the center weight is loose.