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Joelmoak
09-23-2013, 01:33 AM
I have an '06 3500 Diesel that was a lease and has a governor. I have an issue when I'm driving it will start decelerating until I move the pedal and it is ok for a while and does it again. If I don't move the pedal it keeps decelerating. If I move it down and up slightly it seems to correct it.

Also, the cruise control works sometimes and doesn't sometimes. Both these problems seem to come and go....

I changed the fuel and air filters and ran three tanks of fuel injector cleaner.

Any help would be appreciated.

sikwan
09-23-2013, 04:09 AM
Decelerating from what speed?

Aqua Puttana
09-23-2013, 12:13 PM
...
Also, the cruise control works sometimes and doesn't sometimes. Both these problems seem to come and go....

...
Any help would be appreciated.
First thing that I would do is adjust the brake switch. If that doesn't correct the problem then the brake switch contacts should be tested or the switch replaced. The part isn't that expensive.

The brake switch adjustment method post # is listed in the Cheap Tricks condensed thread. vic

Joelmoak
09-23-2013, 12:16 PM
Decelerating from what speed?

Any speed

sailquik
09-23-2013, 01:55 PM
Joel,
I'm puzzled here.
What speed is your governor set at?
I agree with Vic, if the Cruise control kicks out all the time that is normally a symptom of a mis adjusted brake light switch or bad brake light switch.
In your initial post you say you have to "move" the accelerator pedal to keep a constant speed?
I'm wondering if you are unfamiliar with Sprinter "drive by wire" systems and what you are experiencing isn't normal for a CRD Sprinter.
If you are cruising along, in Cruise Control on a flat road there will be some slight accelerations and decelerations due to turns in the road, wind gusts, anything that changes the overall load on your power train.
If you come to a big valley/dip in the road, the % LOD will go to 0% and engine management will hold back (decelerate) to keep your speed constant, and if the downgrade is steep enough, it will actually downshift the transmission.
As you start up the other side of the valley/dip, engine management will open the throttle (perhaps to 100% if the Load goes that high) to try to maintain your set speed the other way, and may auto downshift the transmission....anything to balance the %LOAD and speed.
So, at any given speed, engine management is capable of taking the throttle position from 0% to 100% with no input from the driver. It's a bit spooky until you get used to it.
Check the brake light switch first as that's the most common cause of the Cruise Control kicking out.
Hope this helps,
Roger

shortshort
09-23-2013, 02:27 PM
Maybe the accelerator pedal is faulty. One of the smart guys might know what reading to expect from it's sensor.

sassmatt72
09-23-2013, 02:28 PM
Also you might want to test your "gas" pedal it's just an electric potentiometer, (a simple rheostat, i.e. twist to increase voltage signal). Your condition sounds to me like the pedal signal is being lost by computer. loose connection, frayed wire, or very likely a worn spot on the rheostat contact area...
good luck, matt

sassmatt72
09-23-2013, 02:29 PM
lol shortshort called first.

riskydnb
09-24-2013, 07:11 AM
Perhaps its a TPS (throttle position sensor) found under the gas petal. You may even get a check engine code. I had one today but it was due to a crack in the turbo hose which wouldnt allow the vehicle to go over 50mph when flooring the petal.

Joelmoak
09-26-2013, 12:21 PM
The governor is set at 75mph. I don't believe this is a normal acceleration since it will happen at 35mph or 70mph. It will be maintaining a speed and then act as if it were interrupted and stop accelerating until I make a movement in the pedal. I do suspect the throttle position sensor but I wanted to see if any of these symptoms triggered anyone who had experienced the same problem before I started replacing things. I drove 300 miles in the last two days and it didn't do it at all.... And then my AC went out....

riskydnb
09-26-2013, 01:35 PM
The governor is set at 75mph. I don't believe this is a normal acceleration since it will happen at 35mph or 70mph. It will be maintaining a speed and then act as if it were interrupted and stop accelerating until I make a movement in the pedal. I do suspect the throttle position sensor but I wanted to see if any of these symptoms triggered anyone who had experienced the same problem before I started replacing things. I drove 300 miles in the last two days and it didn't do it at all.... And then my AC went out....

I have ac parts cheap if you need them shipped let me know, 760-622-0148 -Randy

Aqua Puttana
09-26-2013, 01:38 PM
... before I started replacing things.
I know that the DAD has the capability of monitoring such controls using Live Data. I'm certain other scan tools do too. If I didn't own my DAD unit and I were in your situation I would research whether a simple multimeter can be used to check consistency of the output. A multimeter in proper hands can be a great troubleshooting tool.

Just replacing parts can get expensive with little return.

... I drove 300 miles in the last two days and it didn't do it at all....
Did you adjust the brake switch per the procedure? Has it been OK for that long before?

And then my AC went out....
The A/C problem may be completely coincidental, but I'm not saying to completely discount it as a symptom if the problems return it all could be harness related. Just a suggestion, not a diagnosis.

vic

Joelmoak
09-26-2013, 02:08 PM
I hear a tone coming from the AC compressor (I think) it started blowing warm air (Dallas) after working fine for an hour of the drive. I tried to charge it with freon and the gauge went into the red indicating mechanical failure.... I've started getting quotes on compressors...

I drove for 3 hours yesterday without the decleration problem and I havn't had a chance yet to work on the brake switch. All I have done is reach up and feel it and check connectors.

I'm probably going to end up being the hack mechanic I can afford. I dont want to replace the AC compressor just to find its not the problem, I'm going to try and turn it manually with a ratchet and see if its froze up. Argh!!!

manxtony
12-20-2013, 02:56 AM
I got the very same problem on my 07 but my issue started off doing it on hills. I thought it may have been an air lock in fuel. Then it done it in head winds, I am going to bite the bullet and replace throttle pedal unit..I'm in Canada.

motozona
01-01-2014, 03:48 PM
Would like a follow up guys. My 04 Sprinter has a hiccup every once in a while. It doesn't die it just acts as if I took my foot off the gas??

sailquik
01-01-2014, 04:06 PM
manxtony,
So, when you encounter headwinds, do you downshift to 4th gear to get your RPM up into the more performant and economical range (2600-3100 RPM) or do you continue to LUG your engine @ < 2400 RPM?
Might want to consider a Scan Gauge or similar so you can see if the % engine Load is changing.
If the % engine load changes, your Sprinter's engine management has to change the fueling rate and
associated turbo/manifold pressure to maintain your speed. Nothing you can do about this.
It's the way Sprinter engine management works.
Hope this helps,
Roger

motozona
05-04-2017, 11:16 PM
Cleaned up the throttle sensor ( gas pedal) and replaced the fuel filter . It has been good for years... Now I have a head gasket to replace .. :( :bash: