2007 viano 2.2cdi rough running

[hmang]

Hello all .

The viano is running rough .
Idles ok , my star says all the cylinder speeds are more or less identical . it got a kind of a knock though almost like a cylinder isnt firing proper;ly

Its rough to pick too ,does a knocking thing before it gets spinning .

got new oil / fuel filter / air filter .

no leaky injector seats . even swapped injectors for some used ,but with some test certificates ?

just not sure , star says most things in tolerance .

only thing is air mass is just above the upper limit .

any clues fellas

 

[Frontstep]

disconnect maf and see what happens ?

 

[hmang]

disconnect maf and see what happens ?

wont that put a fault code into the ecu and cause running issues ?

 

[Frontstep]

I am sure your ecu will cope with another code, you already have rough running issues and disconnecting and running then replacing or cleaning the maf sensor with contact cleaner spray may solve your issue easily it should go to preset values, but it could be the harness, vacuum leaks downstream of sensor etc etc

A lend of a sensor could be cheap way of diagnosis.
There are a lot of Ebay specials out there so beware there very poor.

 

[Steve@Avantgarde]

If you have star look at the guided tests.

They will either default via the fault code or there is a complete list of tests, select the MAF and run through the guided diagnostics. No need to disconnect or loan anything.

If you are at your limit of capability or knowledge, then seek the help of an independent. It will cost you less in the long run.

 

[Westheath]

Hello all .

The viano is running rough .
Idles ok , my star says all the cylinder speeds are more or less identical . it got a kind of a knock though almost like a cylinder isnt firing proper;ly

Its rough to pick too ,does a knocking thing before it gets spinning .

got new oil / fuel filter / air filter .

no leaky injector seats . even swapped injectors for some used ,but with some test certificates ?

just not sure , star says most things in tolerance .

only thing is air mass is just above the upper limit .

any clues fellas

Sounds like an injector dripping (faulty nozzle), pull them and have them tested.

 

[hmang]

not got a lot of faith in the test numbers I'm afraid .

the correction figures on star read really good figures on an old set of injectors that I know for sure are knackered.

just tried a set of replacements with printed test reports .....lots of numbers and ticks .....and the thing runs worse than ever

 

[Westheath]

Time for a compression, timing test.

The knock is a clue if its not over/under fueling then it could be wear.

If MB Star reports no faults, its back to basic mechanical testing.

 

[hmang]

the star compression test comes out pretty good , with all 4 in the green .

good idea though, does any one know the acceptable comp figures to look for if i put a gauge on it

, i'll do a leak down too and see what that has to say .


some poor soul on here had a vito , i think, that munched a piston, apparently some engine s were prone to this .
His was breathing badly if i remember .

any one have details on the affected engines for this issue

my chassis
wdf 63981323310304

 

[hmang]

the star compression test comes out pretty good , with all 4 in the green .

good idea though, does any one know the acceptable comp figures to look for if i put a gauge on it

, i'll do a leak down too and see what that has to say .


some poor soul on here had a vito , i think, that munched a piston, apparently some engine s were prone to this .
His was breathing badly if i remember .

any one have details on the affected engines for this issue

my chassis
wdf 63981323310304

 

[hmang]

Here's a strange thing
Runs smooth for a few secs after starting then you can hear every thing change .

 

[hmang]

It appears that
Initially the fuel delivery is governed by the pressure regulator then after 30 or so secs that transfers to the quantity control valve .

There's 2 tests for the quantity control valve

1st is turn ign on measure supply voltage
Should be 3v then rise to 4.5v after 30 secs .

Mine drops to 0v

2nd is signal voltage .

Start engine measure voltage
Should start at 3v and rise to 4.5 after 30 secs .
Mine stays at 3v .

Double

Oh no not another ecu problem ......????