'08 c.v. Trans.dis-engaging

[Mark F.]

Hi, I've got an '08 Crown and quite regularly at around 55-60 K.P.H. (40 M.P.H.) the tranny dis-engages. If it's revved up when it kicks back in it may even chirp the tires. The dealer can't find it and it's driving me nuts. Anyone have any thoughts?

[way2old]

Lip seal cut on shift servo???

[Blue)(Fusion]

Start with the basics. Is the ATF level where it should be? Remember to check when the ATF is up to operating temperature and after you cycle through all of the gears. If it is above or below the fill lines, it may cause issues.

Also while checking the fluid, is it proper color? It should be red. If it is turning brown and/or smells burnt it needs to be serviced.

Next question is are there any codes? Does the MIL turn on? Does the Overdrive Off light flash? If either of the two happen, there is a code stored and you must get these codes as they may indicate the exact cause of the problem.

Finally (for now) does this occur EVERY time you pass a certain speed/engine load? Are there any special things you have to do to recreate the problem or are you not able to recreate the problem the same way each time?

Like way2old said above, it may be a problem with the accumulators. If you don't mind getting a little dirty under the car, they aren't hard to access with pretty basic hand tools. Sometimes the seals can wear out and cause fluid to flow in the wrong places or springs can break and cause other issues relating to shifting.

[fleettech]

I would check the fuel pressure if everything else has checked ok with the transmission.

[dizzle1]

Same thing happen to me, I was driving between 35-40mph cruising the lane in front of me was stopping so i moved to the right lane and floored it. Then it felt like the drivetrain took a hit with a hammer and the rear tires chirped. It made the car look good im sure people heard it, but I think it was a late engagement and the car isn't that powerful.

2006 CVPI 75k

[Blue)(Fusion]

dizzle1, if you're in overdrive and you suddenly floor it, the transmission will usually shift out of OD and into 2nd. This is the most damaging operation you can do on these 4R70W/4R75W/4R75E transmissions. You should gently roll into the throttle and allow the transmission to disengage the OD band and then roll further into the throttle for the 3-2 shift.

Additionally, if you want to avoid the time it takes for the 4-3 and 3-2 shift, then before any throttle change, hit the OD disengage button on your gear selector. It will downshift into third and save you that much time. Although it works best when you anticipate such a necessary action, such as waiting to pass someone on a 2-lane state route.

The tune I have has a safe guard to prevent this very thing. Even if I suddenly floor it, the transmission will disengage OD, wait a split second, and then downshift to 2nd. I no longer have that heavy and damaging jolt associated with the 4-2 shift. The actions I stated above will do the same thing, though.