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View Full Version : Release gas pedal and van “holds back”


JonnyGnwc
08-27-2018, 04:44 PM
Is it normal, when you release the accelerator, to feel the van decelerate? It does not “coast” like my old ford did. You feel the engine sort of holding back.

It has done this since we bought it used at 40,000 Miles.

Now I’m worried this could be related to our new transmission ordeal:

https://sprinter-source.com/forum/showthread.php?p=683464&posted=1#post683464

ptheland
08-27-2018, 06:06 PM
Mine does the same. (Also a 2013, fwiw)

JonnyGnwc
08-27-2018, 06:19 PM
Mine does the same. (Also a 2013, fwiw)

Thank you so much! My mechanic seemed to think it was normal. I liked how my Ford diesel “coasted”, but I’m glad to know there’s nothing wrong with it

NelsonSprinter
08-27-2018, 07:38 PM
Very normal for a Sprinter, when accelerator is off next to zero fuel is being injected in, so you then have the 18X compression working against you, ie engine braking.
If you want to coast, just give it the smallest pressure on the accelerator you can, just not full foot off
The Ford might have had a transmission disengagement feature for coasting, the Sprinter doesn't and has saved my brakes descending mountains hundreds of times

autostaretx
08-27-2018, 08:18 PM
Very normal for a Sprinter, when accelerator is off next to zero fuel is being injected in, so you then have the 18X compression working against you, ie engine braking.

Yeah, but...

Since the Sprinter doesn't have a compression release gadget on its exhaust valves (Jake brake), you get that same 18x compression *back* on the "power" stroke, even without adding fuel. Yes, it gets squished, but then it's still in there pushing the piston back down whilst it's unsquishing.

Most of the Sprinter's engine braking is simply higher ring friction (a result of the extra effort required to *hold* 18x compression).

--dick

4wheeldog
08-29-2018, 01:59 PM
Two things. One, Sprinters push a huge amount of air.....Especially the tall ones. So, like a boat that is slowed very quickly when the throttle is closed, they don't coast well. You can test this one by shifting into neutral as you begin to coast. But DON"T shift back in, until you are stopped.
Second, the transmission is set up to hold the current gear (Most of the time, if the RPM is low enough) when you release the pedal, rather than automatically upshift into the highest gear possible, as most other vehicles do.

smurph
08-29-2018, 11:47 PM
Experiencing the exact same thing with my 2013. Glad i'm not alone.

CJPJ
08-30-2018, 01:14 AM
If desired the Engine designers can offset the engines cylinder/-forward of the crank centerline to reduce the engine braking and increase free wheeling.

Sprinter SS
08-30-2018, 01:56 AM
All of my sprinters have had compression braking. I actually like it, and probably why I get 100 k out of brakes!

manwithgun
08-30-2018, 05:33 AM
If desired the Engine designers can offset the engines cylinder/-forward of the crank centerline to reduce the engine braking and increase free wheeling.

I’ve read about this in regards to 4-stroke motorcycles (vs. 2T which inherently have far less engine braking). It was also mentioned that Honda held the patent on the offset and uses it in their off-road line up (CRF450). Seems silly to be able to hold a patent on such a thing, but I do know that Honda once held a patent on the front brake hose routing, forcing everyone else to make a loop in the hose and go down under the fork leg rather than straight up....

CJPJ
08-30-2018, 02:30 PM
Formula 1 will use cylinder bore offset just to rearrange the packaging.