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Pete, Mercedes Mechanic
Category: Mercedes
Satisfied Customers: 27647
Experience:  Over 15 years experience as a Mercedes dealer technician
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Going to try this, My company has had my work truck in to

Customer Question

Going to try this, My company has had my work truck in to the Benz dealership numerous times but no luck so far and a few parts have been changed.
Hello, I have a 2014 sprinter cargo truck with the V6 diesel engine. We have several of the same trucks just older model years.
Mine....starts, warms up fine. As I drive throughout the day, it begins to idle erratic at stops. Idle will fall and engine "hiccups" if thats the best way to describe it. It does this and occasionally it will just stall and I have to restart the engine.
There are also times where it just cranks and will not fire up right away, but it eventually always restarts.
It seems to drive fine, no issues at high speed 60+mph, however i do notice it lacks acceleration power that our similar 2012 model has.
No check engine light, No stored DTCs and the mechanic says there's nothing that jumps out at him. The high pressure pump has been changed, fuel filter changed, doesn't do this all the time, there are times it will idle fine then all of the sudden just die at a stop. There's times where it runs fine, but lately its been getting worse.
It seems now that as soon as the engine is up to temp the moment I drive somewhere and stop at a red light, the idle goes up and down up and down with that engine "hiccup" so to say. I often have to rev it to 1.5k to 2k to keep it from dying in the middle of a busy intersection.
Sorry for the rant?? any thoughts or insights? It only has 41k miles on it so far
Any input is appreciated.
Submitted: 1 year ago.
Category: Mercedes
Customer: replied 1 year ago.
2 weeks ago, it completely died on the interstate and would not accelerate past 15 mph, at that point the engine just shut itself off and I had to coast to a stop. We had it towed to the dealership. That's when they really dug into it, tore apart the fuel rail and found waxy buildup over the fuel pressure sensor.
They say its bad diesel, but i doubt this. me and all my coworkers get the same fuel in town.
After they gave it back to me and fixed it it honestly performed fine for a day or 2 but then the same things started happening again
Expert:  Pete replied 1 year ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

If they only cleaned the fuel rail pressure sensor and did not replace it I have seen the fuel rail pressure sensor fail in the past before needing replaced to correct this type of fault here.If they did not replace it they need to check and see if this is faulty needing replaced.They need to check it using their scan tool or sds machine to observe the actual and desired fuel rail pressure sensor signal to see if they match.I have found just observing the signal with the key on and engine off you can sometimes see the rail pressure sensor signal jump around and that usually indicates the sensor is faulty.If this sensor was already replaced let me know so we can continue.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 1 year ago.
Hello yes, I believe the fuel pressure sensor has been replaced. I think they replaced the whole rail assembly, or just cleaned it really well.
Is the sensor right in the front facing the radiator?
Expert:  Pete replied 1 year ago.

I apologize for the delay.

If they replaced the complete fuel rail assembly then most likely the sensor was replaced already.It should be in front on the rail.This may be a fault internally with the CDI control unit (engine computer) as this can act up internally and send and see false signals from sensors and solenoids and cause this fault here.If the data has not been checked with the CDI control unit this needs done to see if the CDI control unit itself is at fault needing replaced here.If found that it does need replaced it will have to be programmed and set up by a dealer or authorized repair center in order for it to operate properly.

This will have to be checked into further to see if it needs replaced.I would also have the wiring checked over on the engine to see if any wiring faults are found needing repaired or replaced.

Let me know if you need anything else and feel free to rate my help here.

Thanks Pete

Customer: replied 1 year ago.
going to take the truck back to them tomorrow....its doing the same thing still. Very intermittent though. Acted fine all last week until yesterday. Doing the same thing we described.
The check engine light came on and its code P2453. This code comes and goes...will be on...then will turn off.
The dealer says thats unrelated to my problem, but oh well. They're the experts i guess
Expert:  Pete replied 1 year ago.

O.k.,this can still be an issue internally in the CDI unit itself as I have seen some of these fail before.If they can duplicate the fault they should have no problems testing the fault to locate and repair this issue here.

Let me know if you need anything else and feel free to rate my help here as this is how I receive credit for my time.

Thanks Pete