My poorly van

[Sherbingo]

Symptoms.

1. Engine knocking on cold start but clears up after a 5 minute drive.

2. A fairly small amount of white smoke that smells burnt on the first start of the day (It's not vapour)

3. Sometimes it drives and pulls like a train (mainly at the start of the journey but not always) and other times it will judder in 4th and 5th and gain no speed. I have to pulse the acceleration to get home or drive in 3rd. 

4. The van is very inconsistent in speed and power even when it doesn't judder. Sometime I can floor it in 4th and nothing happens but other times it will go as it should. 

5. 9 out of 10 times the engine does this big shake when I switch the ignition off. 

6. The Speedo and Milometer work intermittently and half the time when they turn on and off the radio volume changes gos down if they are not working and back up if the Speedo/Milometer comes back on. Could this possible be related to the other symptoms?

7. Sometime the wireless key locks and unlocks the van. More often than not it doesn't. 

8. 95% of the time when I relase the accelerator it judders as if I'm a bad driver. 5% of the time it doesn't and it almost feels like there's a slight delay in the action. 


No trouble starting the van but I'm so fed up with it. I've changed the crankshaft sensor, glow plugs, fuel filter, MAS... The injectors pass my screwdriver to the ear test and my leak off test results, although pretty rubbish didn't point me to any specific injector. I can't do a compression test but surely it would run pants all the time anyway? Has anyone got any ideas? Is it just possessed?

[Sol]

I never asked, what engine do you have? Apart from any weird BSI behaviour, which could be caused by water ingress or corrosion, if you have a doser valve, it could be the source of your problem.

With the amount of carbon in that intake, the doser valve controls the intake getting air and egr gases in the required proportions, and acts as an anti-shudder valve when you shut the engine off, it's probably caked in carbon and causing all these problems.

The later B9 engine no longer has the doser (mine doesn't) but my M59 which was a 2007 had it and I always suspected it of causing weird running issues, smoking on startup from cold then suddenly running perfectly as soon as it warmed slightly. I blanked my egr and it became almost perfect, but if I disconnected the MAF (mas as your calling it) it also ran perfectly. I put it down to bad egr / air control from carbon build up. The actual issue could always have been the doser valve.

Worth considering.

[Sherbingo]

Thanks for your help Zion, I keep meaning to put my details in the signature! Its a 1.6 HDI but that's about all I know atm. It's a 2010 (before the shape change). I've heard about these doser valves but Google never lead me down that route but I'm certainly going to try and find out if I've got one!

I've had so many theories but I think that after seeing that carbon build up the other day it's pretty much confirming that this is something to do with either this doser valve, egr or airflow. I've got some work to do!

[Sol]

Ok mate, this is the doser (or doseur in French) circled in red. (I notice you post mostly in the M49 (mk1) forum - which one do you have from the list below? (2010 could be M59 or B9 as they overlap for a couple of years) - click for larger image. The doser is also really the mixer valve for egr vs fresh air. 

Imagine the engine wants fresh air only (egr is only open at idle or on over run) and your doser is sticking sometimes on the egr port, which is not open, you would get a near stall / shuddering / cutting out surely.

   

M49:

   

M59:

   

B9: