Vito 2011 110CDi - poor idle when cold

[BenBrown]

Hi, Just bought the above Vito with 135K on the clock with a cold running issue.

Basically, it starts up fine but then within a few seconds the idle is hunting up and down and it can easily stall at a junction during the first 5 minutes. After that van drives perfectly. It drives fine when warming up its just the idle that hunts about and it can stall.

I have come to the conclusion that it could be the Fuel quantity control valve on the high pressure fuel pump, trouble is on my van its buried underneath. It took me 5 minutes just to find the pump and I cant even see the valve without stripping lots of pipes off.

I did discover a two pin (one wire pale blue) connector swinging in the breeze, it exits the main loom just behind and below the oil filter on the near side of the engine and is about 6" long, couldn't see any logical home for it, maybe its a spare ?

My simple code reader couldn't find any fault codes.

Any ideas ?

 

[BenBrown]

Also anyone had any experience of the valves on eBay - Chinese £33, Delphi £68 or Mercedes £150. I imagine the Delphi one is OK.

 

[91dm]

Any smoke or diesel smell around the engine?

I would go with a genuine second hand part before the cheap ones.

 

[BenBrown]

No engine runs perfectly when its been running for five minutes, and also drives fine when cold just has erratic idle. On my engine though the high-pressure fuel pump is right down the side of the engine an absolute pig to get to. Might be able to access it if I pull out the fuse box, though I am not sure

 

[mersum1es]

I would start injectors... leak test and elctrical values reading, at cold engine of course. Way more common than FQV issues.

 

[BenBrown]

Hi, Do you mean leaking from the nozzle or excessive leak back through the leak off return pipes ? I haven't had the car long but it did flag a high oil level warning shortly after getting it and the oil level was very high, I have since done an oil and filter change on it.

 

[BenBrown]

Just checked my oil level and it does seem to have crept up again. Not done any long trips for it to have been doing lots of DPF regen cycles but have done quite a few short trips where the idle has been poor. I dont have any decent diagnostics to look at DPF back pressure or fuel trim values. Might have to invest in some, cant imagine those injectors are easy to get out either and dont suppose I can test them very well.

 

[mersum1es]

I meant injector tank line leak, but sure if your oil level creeps up, its either injector not closing properly on idle, or continuous regen.

 

[Supernoodle]

I have come to the conclusion that it could be the Fuel quantity control valve on the high pressure fuel pump,

How have you come to that conclusion?
You have data to show it's pressure related?

Also, first start in current temps I expect it will be in pressure control valve control mode for first few mins.

 

[BenBrown]

Hi Supernoodle, I thought it might be the Fuel Quantity Control valve because my symptoms exactly match those of another post on line that turned out to be the FQV and it is reported to be quite a common failure. However I am turning away from the FQV in favour of injectors as I think my sump oil level is rising, I will measure it carefully and monitor over the coming weeks. Also after not using it for a few days, as I pulled away from a cold start I thought I heard a bit of a rattle connected to engine speed, this disappeared after 10 seconds or so, possibly pointing at a faulty injector. I will rig up a leak back test and see if one or more of my injectors is spewing fuel from a cold start and maybe bite the bullet and buy some half decent diagnostics so I can rule out a blocked DPF and maybe gain some intel on fuel trims etc, I think I will need it for injector coding if I come to replace any. Am I right in thinking if I buy recon injectors from Germany then I will need to code them to my car ? What if I recon my existing ones will they be just plug and play ? or need coding too?

 

[m80]

I wouldn't bother buying or reconning my injectors again, after a poor experience of trying that route. I would opt for new for the few quids extra.

But if your oil level 'is' rising that suggests issue with the passing of the rings. I would want to do a compression test to rule out the engine being well worn and needing other remedial works.
Does the engine oil smell of diesel?

Another thought, for diagnostics.
Are we sure yours will have a DPF, likely yes, but is it a definite?
Buy a bluetooth EML 327 transmitter for your OBD port, the better one's are around £7.
Download Torque Free to an Android. The DPF temperature monitoring on that will tell you when you're in regen. Being paranoid of these things I've set mine to flash above 525 C.

I use this type, you might find it cheaper??

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[BenBrown]

Hi All, Parked up in a level car park and carefully checked the oil and it's fine, not rising. My drive has a slope forwards and down to the left which gave me a faulty high reading last night. I have done so little miles since the oil change I was surprised it had risen but I will keep monitoring it. It was high shortly after buying it though as I was getting a warning oil level too high on the dash. M80 my van does have a DPF and I already have a simple code reader, but need something that can monitor live data and potentially recode injectors.

 

[m80]

and potentially recode injectors.

A few can recode, but replacement injectors should also have the 'teach in' programmes run for tick over and running.

It may be that others can confirm that the ECU will self learn over a longer period?

 

[Supernoodle]

Injectors have a characterization code which is used to correct the whole fuelling/pressure range back to nominal. This compensates for manufacturing tolerances.
If the injectors are dismantled, this is no longer valid. I'm not sure if remanufactures do or even can measure and create new codes. I doubt it.

Then there is a long drift compensation function which occurs on engine. This is a slow correction that will happen continuously. It only corrects for the zero fuelling point though.. You can speed this process up, ie the teach in.

There will also be a fuel balancing function and and air mass adaption correction, but these will be dynamic, ie short term adaption.

 

[m80]

Injectors have a characterization code which is used to correct the whole fuelling/pressure range back to nominal. This compensates for manufacturing tolerances.
If the injectors are dismantled, this is no longer valid. I'm not sure if remanufactures do or even can measure and create new codes. I doubt it.

Then there is a long drift compensation function which occurs on engine. This is a slow correction that will happen continuously. It only corrects for the zero fuelling point though.. You can speed this process up, ie the teach in.

There will also be a fuel balancing function and and air mass adaption correction, but these will be dynamic, ie short term adaption.

To confirm.
If we replace injectors,
eventually the ECU will self learn, and correct the fuelling of the replaced injectors, and they would be running as ideal?

 

[Supernoodle]

To confirm.
If we replace injectors,
eventually the ECU will self learn, and correct the fuelling of the replaced injectors, and they would be running as ideal?

Only if when you replace the injectors they have valid characterisation codes and you program into the ECU. The other correction mechanisms do not have the authority to compensate for wrong or incorrect characterisation codes.