Acceleration Issue - HELP!

Supa

Member
Needing help please.

When I place the van into drive, it will automatically move forward once my foot is off the brake. As normal.

But UNTIL the vehicle is actually moving, then the accelerator does NOTHING.
IF I am on an incline, and if my vehicle does not roll forwards by itself.
Then I cant go anywhere, I'm stuck.
I can place the accelerator to the floor, and nothing will happen.

My immediate thought is torque converter, yet it does not seem to make sense.
It's as if it is a sensor issue? Yet, when plugged into a computer, the accelerator is registering 100%. Yet, there is somthing stopping it from applying power at take off.

I am open to ANY suggestions at this stage.

2008 315 Sprinter Diesel.
 

sprint2freedom

2008 NCV3 170ext
What happens in Park, can you rev the engine?

Have you checked for codes?

The accelerator pedal assembly has two potentiometers which are checked for agreement by the ECU, presumably to prevent unintended acceleration arising from the failure of one of them.

Perhaps one of yours has failed or is failing? If you have a scanner that can read Sprinter specific data.. such as the Autel MD802, a live readout of the two accelerator pedal position sensors can be observed and you may be able to confirm or disconfirm this theory.

If the two sensors only disagree for the beginning part of the pedal range of motion (e.g. 0-10%) perhaps that would be enough to prevent the engine from responding.

It's also possible that you're running into an intentional decision designed to make the best of a bad situation (sensor failure). The logic may be.. if the vehicle speed is zero and the two sensors disagree, do not respond to the accelerator. If the vehicle speed is >0, then respond using the average of the two sensors, or the most "plausible" one.
 

Cheyenne

UK 2004 T1N 313CDi
Check the brake pedal switch. If the ECM thinks the pedal is pressed (or more importantly, not released fully) then it will limit acceleration.

Try resetting the switch by pressing the brake pedal with one hand and pulling the switch plunger out with the other. When you release the pedal it will correctly adjust the switch.

You should also be able to monitor the switch operation through a scanner such as the Autel MD802 previously mentioned.

Keith.
 

Supa

Member
UPDATE: (And wow it gets even MORE weird and confusing.

Plugged it into the computer - No Gearbox related issues or issues that could cause a fault.
Brake Pedal Checked - Yes tested another sprinter, and when the brake is pressed and accelerator is pressed, it still idle's up (yet mine does not)
Had a gear box tech inspect the gearbox (Thinking it's the Torque converter) - The Torque converter is working great he said. Once the vehicle is moving forward, everything is fine.

SO, we have NO idea why the vehicle has NO power unless the vehicle is actually moving.

I am hoping for a miracle, as we have NO ideas where to go next.
 

220629

Well-known member
Just something easy to check.

Check the hose from the engine air filter box down to the turbo. That needs to be properly installed, secured, and tight or there can be odd acceleration issues. By extension, I suppose an MAF circuit problem may be possible.

Information. Not a diagnosis. That wouldn't necessarily explain what seem to be transmission issues.

vic
 

98Firebird

Well-known member
Sounds like a failed torque converter to me, I've never had a Sprinter (maybe any vehicle) throw any faults with only a faulty torque converter one way clutch (stator). If you are careful you could do a stall speed test which would give you a pretty good indicator of whether or not it's the torque converter (rpms will only rise ~100 rpm when doing stall speed test if the torque converter stator is bad)
 
Last edited:

Supa

Member
Transmission guy tested the car.
Once the car was rolling and under power, he applied the brake.
The stall converter (Torque converter) was doing it's job. (as he tells me).

So he insists it's not the torque converter and something else that is stopping the vehicle from accelerating.

Now, what would a faulty transmission speed sensor do?
Im curious to know.

Guys, thanks for everyone who is giving feedback.
It's now been to 3 mechanics and they are all left saying "I have never seen this before".
 

ptheland

2013 144" low top Passgr
It may not matter, but you referred to your van as a 315. That leads me to think you're not in North America. What country are you in?

You've seen 3 mechanics. Were any of them Mercedes dealers?
 

98Firebird

Well-known member
Transmission guy tested the car.
Once the car was rolling and under power, he applied the brake.
The stall converter (Torque converter) was doing it's job. (as he tells me).

So he insists it's not the torque converter and something else that is stopping the vehicle from accelerating.

Now, what would a faulty transmission speed sensor do?
Im curious to know.

Guys, thanks for everyone who is giving feedback.
It's now been to 3 mechanics and they are all left saying "I have never seen this before".
Never heard of a torque converter stator being tested that way, that is definitely not testing the part I believe to be bad which would be the stator (one way clutch) in the torque converter. Sounds like they are just checking to see if it locked up all the time which would make it stall when coming to a stop in gear, totally different problem from what I'm talking about. Faulty speed sensor would give an implausible reading compared to the other sensors if you're looking at actual values. It would also throw a fault for gear ratio implausible or slipping as it would think there was an issue with input/output speeds. I believe if the transmission were to come out and the one way clutch in the torque converter inspected it would spin both ways which means it is bad.
 
Last edited:

Supa

Member
Hi guys,
Located in Australia.
So just to clarify, when the vehicle is in a stopped position. If you placed a block of wood under the wheel, placed it in drive and pushed down the throttle.
Nothing will happen. Not even the revs will move (This is the part that has us baffled). Not even the slightest movement in revs.
So the torque converter, has not even come into play. As this does not kick in until about 1200rpm.

Once the revs get up (After the vehicle moves off on it's own) then everything works fine, smooth gear changes etc.
It all comes back to that one thing, no throttle when the car is not moving (You can put it in neutral and rev it no worries)

Thanks everyone for all your comments on this.
Im getting sent to another euro dealer today. To be continued.
 

Bvaughan83

New member
I purchased a 2010 144" this summer with 100,000 miles on it. I have the same issue, no throttle response under load, if the vehicle cannot move at idle speed it will do nothing. Ive taken it to the local dealer and a few other shops in town and no luck yet. Your not the only one with this problem. Any updates or other ideas from other would be helpful for me too. Thanks
 

irvingj

2015 RT SS Agile (3.0L)
A very perplexing problem! I'm no Sprinter mechanic, but I can't help but think (and please correct me if my understandings are incorrect!) :

1) This vehicle is completely computer-controlled, "drive-by-wire."
2) Can the engine be revved when it's in neutral? (Does the accelerator position sensor function normally?)
3) When at idle and shifting into gear, is any pressure (a "thunk") felt, indicating the DRIVE shifter position has been established and it's "in gear"?
4) Are there a set of conditions, perhaps a safety feature, in which the ECU will de-couple --refuse to recognize-- the accelerator pedal position sensor and/to prevent the vehicle from moving? (Perhaps something similar to shifter locking in Park if the brake pedal's not applied?)
5) What are the differences in computer sensors/inputs as to when the vehicle is stationary vs. moving? Torque applied to the engine causing it to shift slightly?

I'd be trying to learn these things, but... could the ABS system/wheel speed sensors have something to do with this? Just a guess! Sure sounds like an intermittent electrical issue.

:popcorn:
 
Last edited:

Supa

Member
WOW, I feel slightly relieved I am not the ONLY one with this problem.

OK, lets answer some questions.

1: Yes, electronically controlled.
2: Yes the engine is fine in neutral and can be revved.
3: Yes, when placed into gear, it wants to move on it's own. (Yet if somthing is in front of it, like a speed bump, then it wont move and you are stuck)
4: I dont know :(
5: Again, not sure.

I thank you that we are throwing things and ideas out there.
My thought was some kind of gearbox sensor failure, that wont recognise the gearbox spinning.
Not sure if there is such a thing.
 

irvingj

2015 RT SS Agile (3.0L)
So if I understand your symptoms correctly: if--

a) engine is running, at idle, with no warning lights on
b) parking brake is off
c) foot brake pedal is not being pushed
d) transmission is in D --in gear-- but "bumping" against something so it won't move forward on its own

then, if you press down on the accelerator pedal, engine will not increase rpm? Nothing happens? Does anything happen?

And the other good question: does this also happen in reverse?
 

sailquik

Well-known member
Do you have "ParkTronic" with the sensors in the front and rear bumpers?
Could be that the sensors are looking down rather than forward maybe?
Do the front and rear Parktronic lights illuminate in a sequence?
Roger
 

irvingj

2015 RT SS Agile (3.0L)
Great thought, Roger! I forgot that many new vehicles have got that sort of thing... too bad it doesn't seem to be the case here, if a Parktronic system isn't involved...

Bvaughan and Supa-- next thing I'd do --and keep in mind I'm NOT a Sprinter technician, I'm just going through some pretty basic logic here-- is to get a live feed scanner on there to see if there's any registered change in "throttle" position while stepping on the accelerator pedal, in those conditions listed above. My TDI VAG-COM software will show this on my VW. Not sure if it's called the same as on a gasser, I know diesels really don't have throttles.... but I think it's still called "throttle position."

If it shows appropriate change (on my VW it's shown as a percentage, IIRC), then that's working and I'd start looking downstream, maybe at the ECU. If no change registers when accelerator pedal is moved, I think I'd look at wiring harness(es) first, just to see if there's any physical movement involved when the transmission is put in gear and "bumped" against a stop. At least, to eliminate a physical/mechanical issue. I really can't envision a problem with the torque converter or transmission if the engine just won't increase rpm when the go-pedal's pushed.

Did any of these shops you've been to have the real MB software stuff to do a thorough analysis? If either of you are near Colorado, I'd make a beeline for Dennis!

In any case, a real head-scratcher; hope you guys can get it figured out -- and keep us posted!
 

ptheland

2013 144" low top Passgr
I would be inclined to rule out the accelerator pedal by trying another one. I kind of doubt that is the sole problem, but it not a difficult part to swap out just to test.
 

Top Bottom