OM642 320CDi rail pressure too low

[zedmeister]

Still having trouble with my car - as a standard diesel, it jerks with lack of power only when cold. When warm it runs fine. When the Brabus D6 unit is refitted it is completely undriveable as the jerking occurs even at half throttle and then throws the engine management light on with the following fault:

2047 Rail pressure monitoring via volume control valve The rail pressure is too low.

Indie suggests fitting a new common rail with sensor on the drivers side (right side). They are around £600 but he is not sure if it will fix the issue.

Can the sensor be bought without the rail? Do you guys think this is the issue?

 

[Roxie]

The volume control valve is on the high pressure pump.
It could be the pressure sensor on the rail and if it does unscrew it will not reseal it needs to be changed with the rail. It could also be a blocked fuel filter and many other things.

 

[zedmeister]

We have already changed the fuel filter for a new genuine one.

I'm glad you told me that it will not reseal as I was about to unscrew it today. A company says that they can supply just the sensor if I unscrew it and give them the number but you are saying that it could be the valve on the pump by the error. Any way of telling for sure? The car is quite sooty on the exhaust as well.

 

[Alex Crow]

Could be a low pressure supply or blockage problem - the filter has been changed, which would be a good guess.
Then we have the HP pump, which is unlikely to be at fault. the quantity control valve (mounted with the pump) is known to play up, and might be at fault. Equally the pressure sensor and pressure control valve could also fall under suspicion.

Might be worth a general thought about what fuels may have been used (we see questionable things in peoples tanks, almost always causing trouble!), if any water is in the system, and if there are any other clues (past faults or repair work?).

My guess is the quantity control valve, but workshop testing ought to help...

 

[zedmeister]

I always fill up at Esso, using standard diesel or premium diesel. Used a couple of tanks full of premium recently to see if it would clear up but no difference. In my ownership, I have changed a whole load of sensors such as lambda, MAF, exhaust back pressure.

The error code came from the indie using Modis. Would Star pinpoint the issue?

Roughly how much is a volume control valve? Is that the same thing as the quantity control valve you mention on the pump side?

I should also mention that this has been going on with the car for many months - seems perfectly driveable without the Brabus kit fitted but there is a slight fault there when cold only. Accelerates well after just a few mins of driving, but fault can show up after 20-30 mins parked and then floor it immediately.

 

[mersum1es]

+1 Alex above. In addition injector leak may cause trouble, it is sometimes temperature related. Star has guided test procedures for all those components.

Brabus kit rise the fuel pressure and thats the reason why there is more trouble when box installed.

 

[Alex Crow]

Have seen injector leak off issues with the OM642, but not yet at higher rail pressures - usually a starting fault.
However, a good guess and a good point, and may well be.
Note that the Brabus kit uses higher rail pressures.

Quantity control valve = volume control valve (as opposed to pressure control valve).
Price = whatever Mercedes say, around £60 I guess.
Yes, STAR will be more helpful, with more data and tests, and better code definitions.

 

[Dragos B]

Hello mate I have got the same problem, how did you manage to fix it and where??? I'm looking forward to hear from you

 

[Wighty]

Hello mate I have got the same problem, how did you manage to fix it and where??? I'm looking forward to hear from you

The previous posts you are asking about are 2014 dated ... Just in case you didn't spot the date