Transmission slipping at low speeds
 

My 07 Eddie Bauer Expedition 4x4 is slipping at low speeds, usually between 20 to 40 mph. I'm not even sure if "slipping" is using the right terminology, but it feels sort of like the tranmission jerks a few times, then corrects itself and it's smooth driving after this. During this jerking period, it feels as if the engine will stall. Although it rarely happens when I hit highway speeds, such as 60 mph or higher, it has jerked going at high speeds as well. The engine does have a little over 80,000 miles, but other that this annoying jerking, my Expedition runs as good as the day I bought it. I haven't had any other major issues. I change the oil every 5,000 miles using full synthetic oil. Anyone have suggestions as to what is causing this?

I'll lay odds that a transmission flush will correct this behavior. Do you tow anything?

Changing the fluid is worth a try. It took care of a problem I was having on low speed down shift.

No, I don't tow anything at all. I use to own a 1993 Ford Taurus many years ago and when that started slipping, the culprit turned out to be the transmission filter. I know you can't compare the the old transmission in the Taurus to the one in my Expedition, but it's just a thought. Other than that, I'll try the transmission flush.

i am having the same problems on my 07

I brought in my Expedition to my local Xpress Lube for a transmission flush. The bad news is, the service guy told me he did NOT have the MERCON SP ATF made specifically for this transmission. He said either go to the dealer to buy the Motorcraft Mercon SP fluid or buy a generic version from an auto parts store. I stopped by at "O'Reilly Auto Parts" and did find a Mercon SP approved fluid made by "Global". I've never heard of that brand before, however, should I really be putting this aftermarket type fluid in my transmission? What are the risks?

Also, I asked if my 07 had a transmission filter and turns out it does. I could not find a part number for this in the owner's guide, which is odd. Why would Ford omit this from the owner's guide? The guy pulled up 2 different types of tranny filters on his computer that fit an 07 Expediton, but he couldn't figure out which one was the right one for my vehicle. Any suggestions?

I'm not so certain that I would use a generic fluid. A complete flush at a Ford dealer runs $159.99 in my area. i'll bet that most are near that.

You may have to do the work and remove the filter and take it to the parts guy so he can match it. What a PITA.

Considering that volume that these transmissions and torque converters hold and the cost per quart of the Mercon product, a flush is only a few dollars more, 99% of the fluid is exchanged and you don't have to do the work.

On my previous post, I said that it did have a transmission filter. I was told this at the O'Reilly Auto Parts store. I finally brought it in to the dealer today to get the complete flush done. When I asked the service technician to change the tranny filter as well, he said it did NOT have a filter. Several hours later, I picked up my Expedition and the slipping and jerking seemed to have disappeared. I drove it for at least 10 miles, however, as I got closer to home, it seemed to jerk once when traveling 55mph. Can't say if it was my imagination or because I was going uphill? This was weird, but I hope it doesn't happen again.

I have bad news. The annoying jerking is back. Now, it seems to jerk at around 40mph, where as before, it would jerk between 20 to 40mph and sometimes above 60. I don't know what what else to do. Do you guys have any suggestions?

You'll need a diagnostic check. It may not be transmission related at all. But, you still got a much needed transmission flush.

Thanks for the reply. That'll be my next step. Yeah, I'm glad I got the flush done, it needed that anyway. Like you said, it may not be transmision related. On the day I picked up my Expedition from the dealer, the service technician said the old tranny fluid wasn't that dirty and it did not have an odor of burnt oil, which normally would have indicated bigger problems with the transmisson. I was thinking it might be a bad sensor, but the check engine light has not turned on.

Need to have the dealer drive it with you so they can see what is going on.

Sounds like a bad coil pack. I had a similar "slip" before that was a bad coil pack.

Did you figure this out?

Nope, my dealer found it. Happened two different times, but both times it felt like my transmission was slipping.