Volvo V50 2.0D oscillating rpm when driving

Hi

Have 2009 Volvo V50 with 2.0D D4204T engine and MPS6 transmission (Getrag DSG) in with oscillating rpm problem.

It starts fine even with -20C, idles great but when driving then rpm oscillate. Best felt in about 45 km/h at about 1500 rpm.

When speed rises then it's not be felt much anymore at 90 km/h. But about 60 km/h and 1800 rpm still present enough.


It had engine rebulilt few years ago. Then there was DPF problem tha got resolved. Lately EGR was replaced because it was faulty.

Took quick measurement and noticed that cylinder 2 is doing less work. It could not been felt when driving. Removed injectors and got them checked. #2 was faulty indeed. Others were within spec apart from preinjection for two other injectors. Preinjection was almost missing. Owner authorized replacement for one injector.



Replaced injector, reset adaptations and did another test. Cylinder 2 was now firing but no change in oscillation. Didn't think it would change though.



Will try to get this car in next week for more test. Did quick test and unplugged EGR and it gave no change.

Any suggestions?

Hi Volrem

idles great but when driving then rpm oscillate

I'm not quite sure what you mean by RPM Oscillates. Could you elaborate on that please ?

Is it the case that you hold your foot steady on the pedal at 1500rpm and the revs go up and down ?

Hi volrem , does this occur only when driving rather than engine reved stationary. Ive known two issues on the fords with the dps6 and dw10 engines .
First one is the clutch damper leaking .The other is the airfilter allowing glugs of air in on light throttle causing sudden fueling changes due to incorrect load calculations.
If it has the cylindrical filter in the square housing have a good look around maf connection and make sure filter isnt kinked.
We used to see maf dtcs but ford increased the tollerances in the calibrations making it actually harder to find the problem.
Danny

STC wrote:I'm not quite sure what you mean by RPM Oscillates. Could you elaborate on that please ?

Is it the case that you hold your foot steady on the pedal at 1500rpm and the revs go up and down ?

Yes. When driving with cruise control or holding steady gas pedal position revs go up and down. As seen in last picture I posted.

Dcunning35 wrote:Hi volrem , does this occur only when driving rather than engine reved stationary. Ive known two issues on the fords with the dps6 and dw10 engines .
First one is the clutch damper leaking .The other is the airfilter allowing glugs of air in on light throttle causing sudden fueling changes due to incorrect load calculations.
If it has the cylindrical filter in the square housing have a good look around maf connection and make sure filter isnt kinked.
We used to see maf dtcs but ford increased the tollerances in the calibrations making it actually harder to find the problem.
Danny

Yes it happens only when driving. Stationary idle and raised rpm everything is OK.

I have smoked intake and no problems found. Air filter looked clean but I'll check that and replace perhaps. And yes it has cylindrical air filter.

I did think of transmission issue but it happens both with even and odd gears (different clutches). Didn't notice anything unusual in transmission live data and ECU is inside transmission so hard to measure.

Any tips how to check clutch damper issue? I know it has had transmission repaired but I have to admit that it doesn't work as well as others.

With regards the damper , check for fluid leaks around bell housing even if slight , pull out starter and get borescope in and have a good look.
The pids you can view in datalogger for clutch speeds and the duty pwm to clutches but as you say it happens on both shafts.
Also check the fluid level , this may be the tcm anticipating a gear shift check the pcm and tcm calibrations are right up to date so you can ensure they match .
Danny

Have you got any specific vehicle information, so that we can determine the configuration?

Is the effect you are feeling, like a standard single cylinder misfire, or is it anything like this...

https://youtu.be/gerhI3TI-1c

Dave Hill wrote:Have you got any specific vehicle information, so that we can determine the configuration?

Is the effect you are feeling, like a standard single cylinder misfire, or is it anything like this...

https://youtu.be/gerhI3TI-1c

Have not had time yet to work with it but no misfire is felt. Even with that faulty injector nothing was felt. It's just like in your video.

Hava had these before with automatic transmission but this one is DSG so little but different.


It's 2009 Volvo V50, 2,0D with engine code D4204T and transmission MPS6. Just as stated in first post. I can give VIN but what else configuration info you need? This MPS6 is Getrag 6DTC450 (Ford PoweShift).

Dcunning35 wrote:With regards the damper , check for fluid leaks around bell housing even if slight , pull out starter and get borescope in and have a good look.
The pids you can view in datalogger for clutch speeds and the duty pwm to clutches but as you say it happens on both shafts.
Also check the fluid level , this may be the tcm anticipating a gear shift check the pcm and tcm calibrations are right up to date so you can ensure they match .
Danny

Thanks for the tips, I'll check these out. EMC and TCM SW is up to date and correct. Reloaded these myself some time ago.

Have you any look with this as yet volrem?
Just a thought can you see a pid in your live data for gearbox torque limiting would be worth monitoring it when fault occurs ive had a kuga this week and I ended up replacing the clutch and damper assemblies.
Danny

I did have some time. Can't share any data until monday but oil level was checked. Added 0,2L but we can say it was OK.

Clutch pressures jump around even in idle about 40 bar. Gearbox issue indeed.

Will do some more test on monday and can share some graphs also.

Ok I had sime time to check it again and get some data.

First a video that shows problem:


Cars sationary amd engine at idle clutch pressure varies a lot. NB! Graph shows measuring unit in bar but actually it's in mbar.








I did run transmission adaptations routine and it went a lot better but problem still present. I will send it away to transmission specialist.