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Ford Explorer, Surging and Hesitating

My extremely used Explorer was driven off the lot, and ran like a champ for 3 months. One morning, I started it up, and noticed a chugging sound. While backing it out of the driveway, the truck felt like it was going to rattle apart. This was a sudden change. When I hit about 40mph, and I’m in 3rd gear, the truck hesitates and chugs along. If I stomp on the accelerator, the truck will kick into 2nd gear, and stops chuging for a second, then the gear changes back to 3rd and the hesitation starts again. If I disconnect the battery for a few minutes, then connect, I can drive normally for about 10 minutes, then back to the surging/hesitation. I’ve heard this might be a problem with the oxygen sensors or the mass air flow sensor. Can anyone confirm this problem?

Well, if you put a bunch of car stuff on a dartboard, put on a blindfold and started throwing darts at it you could hit O2 sensors and MAF sensor. You could also hit spark plugs & wires, fuel filter, fuel pump, ignition coil etc.

What year is it? How many miles? Is the check engine light on? Presumably you’ve owned it for 3 mos. What do you know of the maintenance history? I’m going to guess nothing.

If it was me I’d do a full round of basic maintenance before anything else. On my list would be thorough cleaning & check of power cables/battery terminals; charging system/battery check (maybe your headlight problem is related); new spark plugs & wires (unless I checked them and they looked pretty new); new air & fuel filters; fuel pressure check; MAF, throttle body, EGR system and IAC cleaning; vacuum gauge to check out basics on likelihood of vacuum leaks, exhaust restrictions, compression issues; all fluids including transmission pan & filter.

Any of those things may or may not help the problem you are having. But I would be doing it as basic maintenance - not as “repair.” If all of the maintenance is in order and there is still a problem then you can look toward repair.

Hello, Cigroller! Thanks for your response. It’s a '92 with 240k miles on it. I have owned it for about 8 months. I’ve been living with the chugging for 5 of those months. No check engine light (the light actually works, but goes off right after starting the car). There is no way of knowing the maintenance history on it…got it from a little used car lot in town.

Here’s what I’ve done so far…
New battery and terminal cleaning, alternator checked out great. Spark plugs and wires were new when I bought it. The fuel and air filters were new as well.

Sounds like the next steps are fuel pressure check, MAF, throttle, etc, as you listed. I’ll see where we are at after that next round of maintenance checks.

Thanks again for the advice!

Just wanted to get back to you about the Ford. It turns out the spark plug on the right back side near the firewall was never changed! The other plugs had been changed before I bought it, but it seems this engine is configured so that one plug is nearly impossible to get to without 2 guys working on it…the one on bottom working blind, the one on top guiding. That plug was so burned out, it was causing the problem. That one plug being changed, and the timing adjustment made it run like a champ. Thanks again for responding to my post!

Don’t let 'em fool you,
That spark plug is not that hard to change, I’ve it done four times over the years on my 91 and 92 Explorers ( had both at the same time, his & hers ).
Those ‘2 guys’ are over thinking it, they fooled themselves. ( it only takes one )
I’ll bet they’re trying swivels and extensions and every fancy tool in their box.

  • what it takes is LESS tools. -

I change mine with a short/stubby ratchet and spark plug socket, that’s all, from the top,
with the engine cool enough to reach my arm down there. That’s how you get down there to get the plug out, your arm is the only flexible joint needed to reach along with some finger tips . After breaking loose the old plug, unscrew it with finger tips ( an inch of vacuum hose can make it easier to grip.) Same with installing the new plug, just finger tips to screw it in most of the way then that stubby ratchet in the palm of your hand to tighten it.