Momentary Hesitation

[FordandPolaris]

My truck started acting kind of funny while doing highway driving a couple weeks ago. As I am cruising along at about 70mph, it feels as if the engine skips a beat at times. Its started and stopped as fast as I can say "whoa." It only happens if it is on an uphill part of the highway.

It is not my transmission slipping, since it does it in both 3rd and 4th gear. It also doesnt seem like a misfire since I do not get any misfire codes. In fact it doesnt throw any codes that would be a logical cause of the problem. It runs perfectly fine at all other times (smooth idle, no problem accelerating). I am going to start with the fuel filter since it probably should have been replaced 5 years ago anyways, but any other ideas or experiences are welcome, thanks in advance!

 

[joezek]

I had same symptoms and problems on mine. It started immediately after I washed the engine- big mistake. The seals for the spark plug leads had been in bad shape and allowed water into the spark plug cavities on 5 cylinders. I cleaned out the water and cleaned the spark plugs, and it still had problems- probably from bending and moving the COP's that were on there untouched for 120K miles. After that I ended up replacing a few of the COP's. It would idle ok most of the time, but miss horribly under load. I never got a check engine light or any codes.

 

[FordandPolaris]

Ok good to know. I just replaced the #1 coil pack last week after a bad miss, and that one threw a code. It is good to know that it could be a miss with no code. If the fuel filter doesnt fix it, I guess I will just replace the COP's as the cash becomes available. Thanks!

 

[joezek]

On my 98 explorer it had a bad spark plug wire, and when it misfired sometimes the check engine light would flash and sometimes it wouldn't. It's supposed to flash a certain number of times so you know which cylinder. Not sure if the expedition does that too. Last week it had the same problem (my friend now owns the Explorer with 221K miles), and I drove it. I found that the check engine light would only flash if I was stepping hard on the gas for more than a few seconds while it was misfiring.

 

[FordandPolaris]

See that is the weird thing. It happens maybe once every couple days, and it feels like the engine just stops for a split second and kicks in again. I have had misfires in this truck, and they are usually pretty pronounced and obvious, with the entire thing shaking like the engine just came off the mounts. This is why it is leading me to think it is something with the fuel system as opposed to a misfire.

And it really does not affect the overall driveability at all, still does fine at 70, 80, no problem. I just dont like it when things arent working as well as they should be haha. I will replace the fuel filter and report back if I see any change. If the fuel filter does nothing, then I will begin the slow process of replacing all the COP's on a college budget.

 

[joezek]

Ok, mine also was doing that one time. It would just turn off almost completely for a 1/2 second while driving on the highway. It was like I shut the key off. It started getting worse/longer and I put in neutral while it was "dead". I stepped on the gas and it wouldn't respond or go above 500 rpm. I thought the fuel pump was starting to go bad because it was getting louder. I spent a lot of time looking for loose connections on sensors like crank position etc. Then one day I decided to check the oil level for the hell of it, and it was 2 1/2 qts low!! After refilling the oil, never had another problem....I was always changing the oil every 3-4K miles, but for some reason it was consuming a lot of oil that month. I think there may be an oil level sensor that shuts the engine down to save it from buring up.

 

[AWD EXPY]

Mine did that once, a few months ago, as well, at low speed. Just a split second of what felt like turning the motor off.

 

[khpony]

I run into the same thing of and on for the last 6 months. Finally under load it got bad real quick and finally set a code. COP #1. Replaced it and it now runs smooth all the time, even under a hard load.

 

[AWD EXPY]

When I got mine about 9 months ago, the motor ran kind of rough & had codes indicating COP issues. Damn if there wasn't about an ounce of just plain H2O at the plug entrance. I soaked it up, dried it out decently, and it ran fine ever since (except for 2 unrelated ugly moments.)

 

[samuraj]

mine 06 had same symptoms, after new sparks and coils, runs like new.
80.000 miles