Harsh downshift to 1st

windsprinter

New member
I've noticed lately that when just idling along in slow traffic, going a nearly constant speed but slowing very gradually, that the van will shift into 1st with a bit of a bang. This is an automatic shift with no input from me, often just coasting with foot off the gas. It results in a bit of a lurch with engine braking, but the RPMs seem to quickly climb- maybe with fuel being pumped in? I'll have to try and recreate this on an empty stretch of road and watch the instant fuel consumption guage as well and try and see the RPMs its happening at.

I'm unsure if this is normal for Sprinters or if the tranny needs an adjustment - about 4500 km now.
 
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dilleyoshempy

Guest
My sprinter does not do this, you should only feel a momentary release as if it poped into neutral then an engagement of 1st, no jerks or bangs. Hope your issue gets resolved.

Had an issue similar to yours in another truck and it turned out to be lose transmission mount bolts. Do you know if your fluid level is correct?
 
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Barrelsaver

New member
My '08 144 Cargo did the sudden downshift routine a couple times in the first 4000 miles, but not since.... no action on my part , I was just idling along at around 8-10 mph, when all of a sudden it downshift with a thud! It was alarming at the time but nothing else happened and at 11000+ miles now there are no apparent problems.

Just thought you'd want to know!
TK
 

windsprinter

New member
Hey Barrelsaver, thats sounds identical! Probably the same mileage too! I tried to recreate it a couple of times since and, like the computer when the tech guy is there, of course it wouldn't do it. I hope it will just go away like yours did.
 

abittenbinder

Doktor A (864-623-9110)
I'm unsure if this is normal for Sprinters or if the tranny needs an adjustment - about 4500 km now.
Adjustments in the normal sense are not possible but you may be interested in knowing that the Sprinter auto transmission has an adaptation feature that operates on several levels. It adapts to your short term driving style as well as long term wear and tear. Some of these adaptives are short duration ign cycled (not memorized) such as the adaptive influenced by driving style and others are long term such as shift time and are retained.

The adaptation can be reset at the dealer level if the transmission has major component replacements that require relearning.

Your case likely involves the (longer term) shift time adaptation. Shift time being defined as the time it takes to disengage one clutch while engaging another. The decel downshift occurs while coasting down. Your new vehicle's abrupt decel shift shock to first will likely diminish during normal adaptation. Doktor A
 
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Barrelsaver

New member
Thank you Doktor A! At last some technical expertise to explain the phenomena...the high-tech MB tranny has a mind of its own and is learning to shift as we drive! Please continue to share your expertise with us when you see we need it.
Best regards,
TK
 

windsprinter

New member
It must have taught itself a lesson then, because I haven't been able to recreate it since, nor has it done it on its own since. The Sprinter is young still and going through a 'phase' I expect!
 

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