After transmission flush, torque shutter
 

Just had my 2007 f150 transmission flushed. While driving the next day I noticed a shudder when downshifting from high to a lower gear. Truck shifts smooth going up. Also shifts fine when you put your foot "into it". It is most noticeable in high gear when applying gradual gas to make it down shift. On flat ground it is a very brief shutter. When under load( going up a hill) it can be loud and quite pronounced. WHAT HAPPENED? 70,000 miles. This is my second flush and fill so I certainly maintain the truck. It hasn't been abused or over worked towing heavy trailers. Could it be wrong fluid? What can a mechanic hurt by swapping fluid? I'm dumbfounded.

It's not the plugs. I have experienced that kind of shutter. This is different.

Sounds like your torque converter is having issues with locking and unlocking.

I have the same exact your problem but only when under tow. But, since you have just changed fluid, I have to say that's your problem. Wrong type or wrong amount.

The dealer changed the fluid.

Took it in this morning (to the same dealer). They think it is the torque converter. I just don't understand how servicing something can break it?

I have heard that flushing a transmission is not a good idea. Have heard countless stories just like yours.

I'm having a similar issue as you (well it started like yours), I get a shutter when downshifting at highway speeds after slowly applying the throttle. Now it has grown to delayed and rough engagements into drive (either from park or reverse). Most of this only happens when the truck is up to temperature though and seems to have started after I power washed the engine.

I've read that a missfire can cause a similar situation as we're experiencing (not my delayed shift though) but for you it seems to be a bit too co-incidental that it happened right after a transmission service.

My truck is at around 190k miles and is due for a transmission service. I'm just waiting for my spark plugs to come in and I'm going to change those out (due for a set). I'm also going to get the truck into the dealer for a fluid and filter change. I know they don't recommend doing the filter but at the millage I'm at I believe it should be done.

Plugs can make a jerking feel when under load at low rpms and high gear.

This feel and sound is similar to hitting rumble strips.

I have researched some other threads that say fords and Hondas are susceptible to this after trans flush and fill

I'm really wishing the dealer had advised me against servicing and maintaining the transmission. That it would damage more than it would prevent.

if you just did a drain and fill youd be fine...the issue with flushes is it uses an external pump to exchange the fluid..what may have happened is some dirt may have been dislodged and got someplace it shouldn't have been

Throw a transmission additive in it. I use "TransX" ... There are other brands that work well too.

Yep for some reason even though well intentioned a transmission flush is like rolling dice and really not worth it. As stated above just drop the fluid and then refill. Yes it will be mixed with some old fluid but a flush can release some particles from the pan magnet or some place else and cause issue.