Has anyone elses suv done this at 45 mph in overdrive???

[JLS81]

I have a 2008 Mercury Mountaineer. Been experiencing an odd problem that NO mechanic I've taken it to can seem to diagnose... and due to their "guesses" it's cost me $1800+ to "fix" the problem...

-New rear differential put in - didnt fix problem
-New transfer case put in - didnt fix problem either

The issue seems to be isolated to about 45 mph , while in overdrive...

Heres a link to a video I made of what my mountaineer is doing...
It starts about 11 seconds into the video...right after the rpms drop and it shifts into 6th gear...
https://www.youtube.com/watch?v=F40UYjv6dz0

If anyone else has experienced this, let me know what you did to fix the problem

 

[D Hook]

Does it do it if you're in 5th gear?

Does it do it if you have the cruise control on?

Reason I ask is that I get a little tach jumping at the same speed if in overdrive but not if the cruise is set.

 

[matsavol]

Could be Torque Converter lock clutch slipping. Once it locks the RPM drops a bit, which causes the transmission oil pressure to drop a bit, and then will cause the TC to unlock/slip. I did have similar RPM fluctuation around that speed at light throttle in the past but it got fixed (among other improvements with transmission operation) once I had my transmission pan dropped, filter and fluid changed. It was only $200 at Ford dealer. The new fluid should not increase the fluid pressure but it will be more "sticky" (fresh friction modifiers) and the TC lock clutch will be able to hold it in locked state.

Please note this is just my personal speculation about the issue... feel free to (dis)agree.

 

[steve6534]

Could be Torque Converter lock clutch slipping. Once it locks the RPM drops a bit, which causes the transmission oil pressure to drop a bit, and then will cause the TC to unlock/slip. I did have similar RPM fluctuation around that speed at light throttle in the past but it got fixed (among other improvements with transmission operation) once I had my transmission pan dropped, filter and fluid changed. It was only $200 at Ford dealer. The new fluid should not increase the fluid pressure but it will be more "sticky" (fresh friction modifiers) and the TC lock clutch will be able to hold it in locked state.

Please note this is just my personal speculation about the issue... feel free to (dis)agree.

I'll second this notion. In fact I just got done changing the fluid and filter myself this weekend due to the same slip in the same situation (only in 6th gear, TCC locked, speeds around 45 MPH). After the change the symptoms are gone ! Search for "torque converter shudder" and read what some others have said. Some have replaced the torque converter as well but it sounds like in a lot of cases a simple fluid / filter change will correct the problem.

 

[JLS81]

D Hook - it only does it in 6th.. I've turned the overdrive off to see if it will do it and it hasn't...thanks for your response matsavol...I've been reading quite a bit and I'm damn near convinced it is torque converter shudder. ..now i just have to find someone who will know how to change my fluid without charging me dealer prices

 

[D Hook]

Just wondering if you've had a chance to get a fluid change and if that took care of it. Mine started doing the same thing just yesterday; sounds like it's running over small patches of rumble strips on the road at about the same speed yours' was showing. Only did it twice. But it's upped my concern now.

 

[JLS81]

I fixed the problem!

I sold it.



I couldn't take it anymore!

 

[superinstaller]

Sounds funny but mine did it until i changed the sparkplugs. It acted like a torque converter issue

 

[D Hook]

Just had plugs changed when I bought the car back in December. Dealer changed plugs as part of the purchase.

 

[michael loibl]

that looks like your torque converter is repeatedly locking and unlocking.Check your brake light switch before u spend any more money. These trucks will unlock the torque converter if you tap the brake pedal even for one second while driving in a converter lock situation. I believe a good scan tool tradeshow converter lock or not live while driving, if you have an assistant watch the readout while you drive. Of course there are many other reasons that can cause the converter to unlock and relock repeatedly

 

[D Hook]

Will the locking/unlocking make a chattering noise and rumble strip-like feel? I don't know; never had this happen before.

Is this transmission set up like a 5 speed and the sixth speed being the lockup torque converter? I have a scan tool that I can monitor what gear I'm in and it reads 6 speeds. Just have never had it happen while I have the scanner hooked up.

 

[joedog]

I had this problem on my 07 explorer with the 4.6 V8. It was an ignition problem. you have a bad coil or spark plug boots. I would try changing the boots and spring connectors first. make sure you use dielectric grease on the connectors.

 

[D Hook]

Just got a diagnosis on mine. Transmission place said it's the torque converter not staying locked up. It drops out of overdrive when on the highway.

Had them drop the pan and change the filter and refill with new fluid. Did not have it flushed. I'll see if it makes the situation any better. If not, remanufactured tranny/converter is the next step I guess.

 

[D Hook]

I've put on about 100 miles of both in-town and highway driving and no problems so far. Transmission shifts smooth and no more tach jumping around 45mph. We'll see after another 100 miles.