Hesitation/jerking problem

[Lukeallen94]

I have an 08 explorer. 103k miles with the 4.6 v8. This problem just started today, I noticed a slight hesitation on the gas pedal in the low gears. Progressively it got worse the longer I drove, as it’s running through 2nd -3rd it really doesn’t have full power. Idle is fine, not running rough at all. No check engine light nothing on the dash, and as I’m getting home I notice when I take my foot off the throttle it jerks everytime. Like a small thunk noise. All in low gears. Once I hit 35-40 mph the problem goes way. (As far as I know. It might just be more noticeable when I’m going slow). Anybody else have this problem? It’s driving me crazy, first instinct is to think transmission is slipping. Hope that’s not what it is.

 

[aboyfromkansas]

It's hard to believe, but spark plugs (misfire) have caused one to think they have transmission issues. #4 and #8 spark plugs are most likely the ones to check first. Sometimes after heavy rains, water leaks through the cowl at the base of the windshield and runs down into the sparkplug wells. I had a similar problem with my 2006 and no check engine light. This was after the car had been parked outside and we hade very hard rains during the night before. I did do an OBD II test and it gave me a P308 code which is a misfire on #8 cylinder. I changed the coil and plug which fixed the problem. I changed all the plugs while I was at it and this is a job that takes a little more time but not that bad if you prep the plugs with PB blaster or carb cleaner the night before you change the plugs. Some others have commented that checking or changing transmission fluid has also been the cause. As you say, hopefully it is not the transmission.

 

[Lukeallen94]

I’ll see if I can pull some codes. You think maf sensor would have same symptoms under load? I would think if the maf was no good I would have a CEL

 

[Explorer_PL]

I have gone through several replacement of plugs and coils on my 06 with the same symptoms you have.
Get Motorcraft parts and change those first. In my case it has worked 100% every time.

 

[WaltZ]

I had a similar problem for a few weeks and no code. Finally the CEL came on for a few seconds. It ended up being a bad plug. Could also be a bad coil, but they usually code once they go bad.

For the MAF sensor, buy some cleaner and clean it first before buying a new one.

 

[Explorer_PL]

Thanks WaltZ, I forgot to add that the CEL would never come on, only when the misfire was severe. Otherwise, it will buck and kick without any codes, very high threshold for 3xx codes on Fords.

 

[Lukeallen94]

So what I’m feeling is definitely under load, and gets worse after I drive for 20-30 minutes. Today the jerking is much worse when I let off the gas pedal, even if I’m doing 3mph. It feels like it slams. And has a strange humming noise

 

[Explorer_PL]

Humming noise .......
That's different. When was the last time you serviced the tranny ?

 

[Lukeallen94]

I just bought it, a couple months ago

 

[Explorer_PL]

If it progresses with temperature, it may be related to fluids, in this case the tranny. It may be your torque converter acting up, hard to tell.

 

[Lukeallen94]

That wouldn’t throw some sort of code for the tranny? I read the threshold for code popping up on the dash lights is pretty high for these trucks

 

[iajet]

Hmm, I have a similar issue but at high speeds in OD or going up hills with OD off and around 40-45 mph. This has been an issue for years and no one has been able to figure out why. MAF has been cleaned, new plugs and wires, new fuel pump, trans fluid change (non of these items were changes for troubleshooting). I even had a tech from the dealer ride along with a computer hooked up to the odb, but could not duplicate the issue. It is wildly intermittent and thought the issue had been fixed when I replaced the fuel pump/gas gauge sending unit.


where

 

[94Eddie]

If you have something other than Motorcraft coils it could be they are electrically interfering with the communication between the transmission and computer where the wiring harness runs near the coils on the passenger side of the engine. This can cause a multitude of symptoms like you describe. Cheap coils can cause a lot of RF interference in nearby wiring which can degrade the data being transmitted through the wires.

 

[iajet]

Assuming you are responding to me...I replaced the wires, plugs and coils probably 50k miles into this issue with no change. It seems better but still wildly intermittent so it is hard to tell.

If you have something other than Motorcraft coils it could be they are electrically interfering with the communication between the transmission and computer where the wiring harness runs near the coils on the passenger side of the engine. This can cause a multitude of symptoms like you describe. Cheap coils can cause a lot of RF interference in nearby wiring which can degrade the data being transmitted through the wires.

Assuming this was in response to

 

[94Eddie]

Assuming you are responding to me...I replaced the wires, plugs and coils probably 50k miles into this issue with no change. It seems better but still wildly intermittent so it is hard to tell.

Assuming this was in response to

Did you use OEM coils?

 

[iajet]

Did you use OEM coils?

I did not, however the coils that were replaced were oem and I had the issue before the coils were replaced. There were no issues with the coils, plugs and wires (that I know of) I just replaced them at 105k miles because I felt it was time. So you think there was an issue with the oem coils also? Thanks 94Eddie

 

[94Eddie]

Probably not if your problem occurred with both sets. Also, the odds of the new set causing a problem out of the chute is remote. As cheaper coils age they can cause the issue I referenced.