C220 CDI W203 injectors

[techcareuk]

Hi, I have a 2003 C220 CDI t-wagon (estate) that has always smoked quite badly.
To give you a bit of background on the cars history I got the car in bad condition about 18 months ago, it was in M55 limp mode and once I took a closer look it obviously hadn't been looked after.
modifying the inlet manifold (removing the swirl flaps and plugging holes etc.) sorted the M55 limp mode problem, I gave it engine oil and filters (including fuel and air) replacement in December 2017 along with a new thermostat and I also did the EGR omit mod ( the one with the circuit to manipulate the airflow sensor output when the EGR open signal is present to match the expected reduced flow values), both mods and service improved the running and performance hugely but it has always suffered being smokey, some times worse than others but usually a constant puffing at idle and huge dark clouds at acceleration, I suspected prior to the car coming to me it had been neglected and run for a long time in limp mode and I assumed it would improve with use.
I gave it two doses of Archoil 6400-D and 9100 which again helped but didn't cure.

The car has currently done 185000 miles ( about 14000 have been done by me since December 2017)

Star is showing Quantity correction values of injectors as the following
Cyl1 5.3mm/3 Hub
Cyl3 -4.7mm/3 Hub
Cyl4 0.9mm/3 Hub
Cyl2 -4.2mm/3 Hub

It also shows current injected qty is 20mm/3 Hub (star shows expected value is 5.0-14.0)

looking at these figures I suspect injector at cyl1 definitely needs replacement but what about the others, do I need to be concerned with the injectors showing minus figures?

If cyl 1 is closest to the bulkhead then the injector in cyl4 appears to have been replaced with a new or recon unit before I got the car so i'm assuming the figure of 0.9mm/3 Hub is good?

and the big question, looking at these figures is it likely the injectors are the cause of the smoke?

Any advice would be very much appreciated.

 

[om613]

I think the CDI2 QCV injector wear limits are +/- 5.
So cyl 1 (...front of the engine) is over the limit with cyls 2 and 3 also quite near to the limit.
Cyl. 4 is the recon, near bulkhead, close to zero shows that.
So it sounds like a 'yes'.

 

[Westheath]

Remove all of them and have them replaced/refurbished as correction values can mask other cylinder injector problems.

1-2-3 are possibly at their limits 4 can affect correction but need further testing to confirm, IE: live data road test and leak off test.

Just because it looks new don't mean its been refurbed or is ok, seen many refurbed injectors badly done.

(But it looks ok in Star)

Leak off test rough guide.

Bosch common rail type

Measure diesel injector return quantity
Start engine
Let engine run until one of the measuring cylinders is filled completely
Stop engine
The maximum permissible return quantity is 3x as large as the smallest return quantity measured


Measuring cylinder of injector


Contents


1 41 ml


2 44 ml


3 50 ml


4 46 ml


Maximum permissible return quantity:


41 ml x 3 = 123 ml

All the injectors are in good order.


Example not ok

Measuring cylinder of injector


Contents


1 50 ml


2 18 ml


3 18 ml


4 10 ml


Maximum permissible return quantity:


10 ml x 3 = 30 ml

Injector 1 has too large a return quantity.

It must be replaced.

 

[techcareuk]

I think the CDI2 QCV injector wear limits are +/- 5.
So cyl 1 (...front of the engine) is over the limit with cyls 2 and 3 also quite near to the limit.
Cyl. 4 is the recon, near bulkhead, close to zero shows that.
So it sounds like a 'yes'.

Thanks OM613.
The shiney injector is actually at the front of the engine cyl1.....

It would be interesting to confirm if the limits are plus and minus?

Today it developed another problem what appears to be slow turbo spool up then after few mins limp mode & EPC error so quickly loosing the will to repair it especially if its going to need 3 or for replacement injectors also.
I may start another thread for that after i read the errors but it may be the end of the road for it

 

[techcareuk]

Remove all of them and have them replaced/refurbished as correction values can mask other cylinder injector problems.

1-2-3 are possibly at their limits 4 can affect correction but need further testing to confirm, IE: live data road test and leak off test.

Just because it looks new don't mean its been refurbed or is ok, seen many refurbed injectors badly done.

(But it looks ok in Star)

Leak off test rough guide.

Bosch common rail type

Measure diesel injector return quantity
Start engine
Let engine run until one of the measuring cylinders is filled completely
Stop engine
The maximum permissible return quantity is 3x as large as the smallest return quantity measured


Measuring cylinder of injector


Contents


1 41 ml


2 44 ml


3 50 ml


4 46 ml


Maximum permissible return quantity:


41 ml x 3 = 123 ml

All the injectors are in good order.


Example not ok

Measuring cylinder of injector


Contents


1 50 ml


2 18 ml


3 18 ml


4 10 ml


Maximum permissible return quantity:


10 ml x 3 = 30 ml

Injector 1 has too large a return quantity.

It must be replaced.

Thanks Westheath.
The new looking inj is at cyl1, its a work car and its starting to look like its becoming un ecconomical to repair.
In adition to this problem it needs various suspension bush replacements and the problem in my previous post so starting to think its becoming a money pit.

 

[Westheath]

Any cars a money pit but the Merc "bullet proof" stuff long gone. IMHO

All limits are +/- 5 on those correction values smooth running at idle test.

Its when you go full live data road test you need to see what's going on if it passes idle and the leak off tests.

Its a shame because they are surviving the rust problems but not the mechanicals like they used to (Sprinters of those years use same engines 4/5 cylinders) and the mileage they can put on a lump will soon show problems and all are CDI related fuel pumps injectors and the curse of the CDI 2/3 the Black Death

Problem is you buy something else and can have to throw money at it.

What do ya do..........

 

[John Laidlaw]

Shame, as Westheath says the rust issues are minimal but ( especially diesel) mechanicals are a challenge . However injector refurb ain’t too painful themselves but with suspension bushes now you may be right - it’s a chance you might do the work and get a couple of years or....
Any consolation to you I spent near 7k in one year on an SL500....

 

[techcareuk]

Thanks guys! lots of good info here and thanks Westheath for explaining the leak off test!!

I'm right at that point where its a difficult decision to bite the bullet and sort these problems or run, Think i'm going to ponder over it this weekend!

Thanks again everyone for all your advice!!

 

[om613]

Any cars a money pit but the Merc "bullet proof" stuff long gone. IMHO
What do ya do..........

Oh yes, long gone, since DC became involved.
In the 1980's, remember that a W123 cost around 3 x a Ford 'equivalent'?