W205 OM626 1.6 CDI rough running on idle - light smoke on acceleration

[humzaahmed155]

Any techs on here that can advise? I'm certain this is leaning towards injector 2 failure. The engine runs VERY lumpy at idle only and smokes lightly on higher rpms.

Shutting off injector 2 makes near to no change in roughness, but any other cylinder shutoff results in the idle becoming weak and extremely lumpy.

This is an OM626 1.6 CDI (Renault, yes I know), and what makes this worse is, the injector shop has said these are all fine!

The picture shows the injection quantities for each injector, what can you guys tell me from the values? I feel like cyl 4 is being overfuelled and cyl 2 is almost dead at idle.

TIA!

 

[Jobsworth]

I had one with similar numbers the other day. To prove the point I swapped number one with number two, and the fault moved with it. A new injector resolved it. I think mine was at +5.20 ish. I’d ignore the number 4 for a while.

 

[Oleks1992]

Are you able to do zero quantity calibration via xentry? I know it can be done on om651

 

[w2052015]

Any techs on here that can advise? I'm certain this is leaning towards injector 2 failure. The engine runs VERY lumpy at idle only and smokes lightly on higher rpms.

Shutting off injector 2 makes near to no change in roughness, but any other cylinder shutoff results in the idle becoming weak and extremely lumpy.

This is an OM626 1.6 CDI (Renault, yes I know), and what makes this worse is, the injector shop has said these are all fine!

The picture shows the injection quantities for each injector, what can you guys tell me from the values? I feel like cyl 4 is being overfuelled and cyl 2 is almost dead at idle.

TIA!

Hi I see this is a few months old but can I ask did you solve this specific issue? I've had this for the last 18 months ... cylinder 2 hiting 5.00 mm/3 when starting coupled with unburnt diesel smoke and shudder and usually under 55 degrees coolant temp. In the middle I had turbo failure and pinging etc etc ... but with all the work I've done incl 2 egr replacements, injector swap outs , maps,maf, etc and I've got the car running great when warm..but on start up under 55 degrees .... this blasted cylinder 2 still hits 5.00 mm/3 at start up with shudder and unburnt diesel smoke... recently I've noted hi pressure egr opening immediately on start up / cold and replacing it makes no difference,it still opens too early so I will.look at that...but if you've had any success I'd be grateful.if you could help thanks. Car is 2015 w205 1.6 Diesel (Renault / Nissan job unfortunately)

 

[humzaahmed155]

Hi I see this is a few months old but can I ask did you solve this specific issue? I've had this for the last 18 months ... cylinder 2 hiting 5.00 mm/3 when starting coupled with unburnt diesel smoke and shudder and usually under 55 degrees coolant temp. In the middle I had turbo failure and pinging etc etc ... but with all the work I've done incl 2 egr replacements, injector swap outs , maps,maf, etc and I've got the car running great when warm..but on start up under 55 degrees .... this blasted cylinder 2 still hits 5.00 mm/3 at start up with shudder and unburnt diesel smoke... recently I've noted hi pressure egr opening immediately on start up / cold and replacing it makes no difference,it still opens too early so I will.look at that...but if you've had any success I'd be grateful.if you could help thanks. Car is 2015 w205 1.6 Diesel (Renault / Nissan job unfortunately)

Sadly bud I got rid of the car, I gave it to a specialist who found knocking in one of the cylinders (I think it was 4? Can't remember now) and they wanted to pull the head off and begin investigating. It's probably just easier to sell at that point and grab something with a 651 in it.

 

[w2052015]

Thanks for reply. Yep I've tried everything. Drives great when warm now, but was pinging and banging for a while, only remaining item is the slight shudder and unburnt diesel fuel now. But my injector situation was exactly like yours...cyl 2 ...no matter what injector was swapped in or out. I'll go at it for a few more months...coolant sensor next...I've a 25 yr old w210 petrol...not a problem...bit of rust. These r9m om626 engines are rubbish for clogging up with soot. Thanks again for revert.