The Dreaded Unpredictable Downshift Disease

FourWheelers1987

A 2017 2500 144” Crew 4x4 High
After Google searching this phenomenon, I guess it's my turn to report this problem.

The 1st time this happened was a month ago while going almost nowhere for 30 minutes in San Diego area traffic. As I passed the accident causing the back up, I shifted my '17 Crew 4x4 OM642 from crawling in 1st gear to 2nd then 3rd to begin getting back up to highway speed. Before I could tap the Tiptronic again into 4th gear, it suddenly downshifted ON IT'S OWN into 2nd with the accompanying rpms almost redlining. I quickly tapped it back into 3 but felt a noticeable lack of power.

I manually shift the 5 speed Tiptronic 99.9% of the time, happily using a Scangauge II. I drove cautiously for a few miles finally getting up to my typical 2800-3200 rpm shift range and made it into 4 and 5th gears. After making it back to the east coast without a reoccurrence, I forgot about this odd event . . . until today.

After pulling away from a red light in 1st gear and manually shifting into 2 in no hurry to get to 3rd gear, the transmission abruptly downshifted back into 1st jarring me and my 2 passengers. I thought I accidentally done it until it occurred with BOOM again a mile or so later after another 1st-2nd shift from a red light stop.

We had a long trip ahead of us and after entering the highway, I noticed that power was lacking again. I drove it home gingerly, cancelling our travel plans. When I came to a stop, I noticed the engine temp was reading 200F+ which is above it's normal 175-180F range even after extended driving.

I've read the other posts on this topic with some great suggestions most of which are above my knowledge base. I'm most interested in how to handle this issue with the Sprinter dealer service dept after I have it towed there tomorrow morning.

Any suggestions would be most helpful.

Puzzled, but ready to insist (nicely) on a fix,

FW1987
 

FourWheelers1987

A 2017 2500 144” Crew 4x4 High
Here's my update for anyone facing a similar issue in the future.

After reading more online, I found the Stephens Service site (again) citing the pros and cons of this beloved OM642 diesel. So, instead of a tow, I ran it for a half an hour on the highway without issues of any kind. This is the 2nd strange incident of just letting the van and I "sleep on it' so it could rectify itself.

The 1st time, it wouldn't start then locked me out by not allowing me to turn the key (the steering wheel was unlocked in case you were wondering) and all electrical power was gone.
I tried starting it in the morning. After opening the sliding door manually, all the cabin lights came on. It started right up. I drove it to Hoehn Mercedes-Benz Sprinter in Carlsbad, CA and they could not replicate it. No such reoccurrence since.

I guess i'll just keep reading and getting a good night's rest in the meantime.

Fingers Crossed,

FW1987
 

Mickyfin

Member
Sounds somewhat unnerving for sure, that would drive me crazy, I'm very OCD with all things, EML included.
 

Wrinkledpants

2017 144WB 4x4
You can't actually manually shift the van. It's more of a shift request. There are a lot of reasons besides just RPM range that the van won't shift to your requested gear. What values are you looking at on the scanguage when this happens?
 

FourWheelers1987

A 2017 2500 144” Crew 4x4 High
You can't actually manually shift the van. It's more of a shift request. There are a lot of reasons besides just RPM range that the van won't shift to your requested gear. What values are you looking at on the scanguage when this happens?
At the moment of the sudden drop into 1st, my eyes were on the dash tach screaming to redline so I can’t answer that.

True, we didn’t get the option of a manual 3rd pedal set-up like the ROW. I’ve been “requesting” shifts since day one according to rpm range as stated and engine load. Per Roger “sailquick” (and others), recommended range of 2800-3200, I would request shifts accordingly. Also, for fuel economy, engine efficiency and emissions system reasons, I’d request a downshift when the ScanGauge ll engine load approached 75-80 due to steeper hills, mountains, and stiffer head winds.
I also like requesting shifts in traffic jams which despite my efforts, is the main culprit for my inexplicable experience and disappearance and reason for this thread henceforth referred to as D.U.D.D.

I’m still open for helpful suggestions to avoid future reoccurrences, since the traffic in and between Florida and NYC is only getting worse.

“And that’s the way it was . . .” Walter Cronkite (1916-2009)
 

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