'JOLTS'

[Marmite]

So say my car is going 45mph, I take my foot off the gas, the car glides/slows down to 35mph and then I put my foot on the gas.
The car 'jolts.' Sometimes it feels like I ran over a brick. Often it is not so dramatic, but there is still a jolt.
Putting my foot on the gas at 35mph this often happens. It sometimes happens at faster speeds and only after I put my foot back on the gas pedal.
I can feel it like it is 'hitting' the car just in front of the gas pedal, somewhere near the axel.
There is no change in the rpm (I am 95% sure) and sometimes it feels like the car is searching for the next gear.
I don't know if I've done a good job at describing what is going on but I am hoping that someone has experienced something similar and knows what causes this.
Thank you!

Exp 2007 XLT

 

[tommyddsr]

Sounds like it could be a u joint. Do you hear any clunking noises when you put it in gear or if you go from drive to reverse and back?

 

[Marmite]

Thank you for replying tommyddsr. There are no clunking noises when I go from drive to reverse and back.
My mechanical knowledge is limited so I watched a few videos to find out about U Joints and I don't think that's it. But I do know where the U Joints are now and I will get under the car and check they are in good shape.
What I should add is that after the Jolt, there is a really brief loss of power which is similar to when a stickshift is out of gear.

 

[FlyBry]

Do the Revs increase on the Tachymeter just before you feel the jolt? If Yes, = transmission went to false neutral, then engaged a gear.
How many miles, and has the tranny ever been serviced?

 

[Marmite]

I don't think the revs increase but I will look out for that.
125k and I've no idea whether the tranny has been serviced. I got it from the police chief about 10k miles ago.
Thanks for the response.

 

[Boostedbus]

Maybe something with torque converter locking and unlocking?

 

[JamaicaJoe]

Motor mounts? This vehicle was in police service?

 

[tommyddsr]

Motor mounts are easy to check. With the hood up so you can see the motor, hold the brake, put it in gear, and rev it up a few times. If you have a broken mount you should see excessive movement of the motor. It will noticeably lift.

 

[Boostedbus]

I would think if it were broken motor mounts it would be way more noticeable on take off and not while cruising from 45 mph down to 35 mph then applying the throttle. The first inertia on the mounts on take off from a dead stop would be dramatically more than while moving and applying the throttle.

 

[jkayca]

Maybe something with torque converter locking and unlocking?

This would be my guess. I had a similar issue with my Honda Odyssey. Turned out to be a torque converter lockup problem.