What was the type of the replacement ATF?

 

I stuck with the original T-IV at the first change when the problem first surfaced, but since then I now have Maxlife in the trans, but the problem persists.

 

That sounds a rough downshift which is quite common on your older u151e. You're fine, keep driving it. My sis's car does the same thing at times.

 

I only have 118,000 on my '03. I do know that the original owner had an accident with the car, so it's a possibility that that may have damaged the dog bone engine mount at the top of the engine which I've since replaced. My next move is to have a shop take a closer look at the bottom mounts which may have also been damaged during that accident...or maybe it's just time to replace them due to dry rot or regular wear and tear.

 

Most people feel a fluid change results in smoother shifts. So right, what fluid?

I’d also wonder if the filter AND O-ring are properly seated. A suction side leak might do that if the fluid type is proper, as in Valvoline Maxlife or just standard T-IV.

 

Almost definitely one or more bad lower mounts. Usually they fail first which transfers stress to the dog bone and finishes it off in short order. Remove the dog bone, then take off the top nut on each lower one and jack up the engine a little. Wiggle the top part of each mount. They should be fairly stiff but I bet one or more are broken.

 

The car was in a front end collision in its early years, which could have damaged the mounts way back then. As I said, I replaced the upper mount with no change. Also, when braking at a stop sign the downshift is rough...except if going down hill to a stop where there is no hard shift at all. Makes me wonder if that's because the broken lower mounts have allowed the engine to move forward ahead of the braking, eliminating what sounds and feels like that hard shift.

 

I have an occasional harsh downshift in my 02 V6, but only when the engine is stone cold. Don’t think too much about it. One thing you can try is a capacitive discharge. Disconnect both positive and negative battery terminals and touch them together for 10-15 minutes. This will reset all the adaptive learning values of all the modules in the car, and as you know our transmissions are electronically controlled and adapt to our driving habits and even fluid to calculate the best pressure for shifting. Should always do this when changing/flushing trans fluid


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