2016 F350 DRW 6.7 No prior trans issues, just started this morning with a noticeable pulling when stopped otherwise seems to be shifting fine. Nothing out of the ordinary recently, short medium weight trailer pull a couple days back, also pretty routine. Only 51K on the truck. Thoughts?


Thanks,


Pete C.

 

 

No audible clunk that I notice, but I can feel it start to pull. When slowing to a stop from speed everything is good until that final downshift to first and then it's pulling again. Fluid level is ok, but it's a bit dark, not "burned" but not bright red/pink like it should be.

 

Better described as a forced downshift or a hesitant down shift???
Do you have it in tow/haul mode? (though that should reset each time you cycle the key). Can you simulate the same problem in tow/haul mode too? Tow/haul will have pronounced downshifts.
Have the "pending" and "present" codes read off the TCM. You need a trans shop familiar with the 6R140 or a Ford dealer with good truck techs. The big box "read your trouble for free to sell you something offshore" generally do not have a reader capability with the deeper software to pull the TCM codes.

Have all systems read. It could be another system altogether? Hill start assist, VSS or other systems could be faulty without illuminating the CEL.

 

No towing today, just ordinary highway use. Nothing notably different in the shift pattern, no harsh shifts, fine accelerating to 75, slowing, etc. only the pulling when stopped. Noticed the pulling from when I first put it in gear this morning. Busy and late day today, tomorrow I'll do some scanning and see if I find anything of value in module codes, nothing in top level DTCs. No hills around here either.

 

No codes in any module, including TCM. Scope clearly shows things loading up when put in D or R, and show the sudden drop in load and jump in RPM when put back in P or N. Definitely abnormal, but it seems the TCM hasn't figured that out yet.

 

Ford has a feature to slightly pull forward when stopped to help keep the unit from rolling backwards.

It is noticeable. Hill Start Assist..

 

No, this is an abnormal condition that just began yesterday after 51,000 miles of no issues. There are also no hills here and the symptoms are definitely no the hill assist which I have experienced traveling in areas with hills. Foot on brake, truck level, engine running, shift from P or N into R or D and it starts loading up very noticeably. On the scope the load percent climbs steadily, when you shift out to P or N the release of load is sufficient to physically rock the truck. Absolutely not normal.

 

 

Certainly possible, but could be other things as well. With no DTCs to provide some direction I need to find the troubleshooting flowcharts and normal readings for a 6R140. I believe I have the service docs here somewhere, but with a move and a few reorgs I'm not quite sure where.

 

I found my service manual and the symptoms appear to be consistent with the torque converter being always on. The way the load reported by the TCM climbs steadily I'd suspect a sticking / leaking solenoid allowing hydraulic pressure to build. At any rate it's still under the base powertrain warranty (also have ESP) so it's at the shop now to hopefully be repaired tomorrow. Hopefully I caught it early enough that it didn't do much damage and require more extensive repair.

 

I'm not quite understanding your description. What do you mean by load? Do you mean the trans feels like its fighting itself or locking up?
Or are you seeing a component take on more "duty" (load) electrically on the scope?

As far as I know, there is no "on" or "off" on a torque converter(in the 6R140. The crank spins so does the converter (the stator that is) which causes fluid to move. The trans starts moving when the stator throws enough fluid to cause the impeller to move..etc...A converter is nothing more than a pump for the trans. And a coupling between the engine and trans, fluid clutch if you will.

As you may know, there is a converter lock-up feature in most if not all of today's converters. It's basically another friction and steel pack inside the converter. When this pack is signaled electronically with a solenoid it sends fluid to this clutch pack to lock the converter to the crank in certain gears and 6th at cruising speed for a 1:1 engine to trans ratio. Eliminating all converter slip for fuel economy. I don't suspect this portion of the system as the engine would like stall and throw codes all day.

If you're not seeing any pending or present codes then I would suspect a mechanical problem in the trans, ((if you have eliminated the hill decent feature from malfunctioning?)). Do you hear the brakes groan when this happens? This is typical of this feature when the brakes unlock or begin to release.

To troubleshoot mechanical trans problems start with a pressure check, You need to read the line pressures in each gear range including park and neutral. This is where you would see any hydraulic anomalies. It would show up as an abnormal line pressure. Too high or too low. This is an indication of a cross leak or a bypassing leak. It almost sounds like a cross leak. That means two hydraulic circuits are being signaled simultaneously and are applying something that should not be applied. Similar to a race car trans brake.

Find a really good ASE/ATRA certified trans technician versed on the 6R140 Torqshift and explain this to him to see if I'm on the right track. Chances are its not the only one he's/shes seen. It's about all I can come up with without being able to get my hands on it.

 

Load as reported by the TCM would climb steadily when put in gear with the brake on, rather like the TCC was gradually being applied due to a sticking solenoid.

At any rate the truck is reported to be ready now (I'm out of town currently). They said the front pump failed and they replaced the pump, torque converter and valve body. Ill pick it up probably Thursday.

 

OK, that makes sense. So they did a pressure test to find the failure?

 

Not sure, haven't talked to the tech yet. Suspect not, they were going dor valve body and when they pulled the pan found metal debries and decided the torque converter was coming apart. Not surprising if the TCC was applying between the brakes and engine, it's going to loose, especially if it applies gradually due to a leaking solenoid valve. Line pressures reported by the TCM were reasonable oddly enough.