KHM

Hi Folks

I've got a W211 220CDI 2006 model with an issue the MB dealer so far have been unable to solve. The car has relatively low mileage (125k kilometers).

Around 2100-2200 RPM while for instance running on cruise control uphill, the car jerks or shudders. Almost like misfiring but as it is a Diesel etc etc.

Certain conditions has to be met for this to happen. No hill or flat/almost flat road, no symptoms, steeper uphill, no issues, but in a long more flat/long uphill, it's very noticeable. if I gear down and RPM goes up to around 3000, problem is gone. Slowing down to below 2000 RPM, problem gone. Low RPM, never any issue regardless of gear as long as in motion.

The same problem occurs when starting to drive/accelerate slowly on flat road or flat uphill. As soon as the rpm hovers around 2100 RPM the car shudders and run unevenly. Like misfiring. At lower speed/2100RPM one can also hear a sound from the engine bay. Sounds like something rotating.

This sound coincides with the jerks. As soon as it's past the RPM and has geared, sound is gone.

The gearbox has been checked, due to fault in a transmission control plate of some sort (very expensive job here) was changed. This was done during last winter and the gearbox really turned bad.

They did a reset of the ECU late spring. Hey Presto! Solved all gear related issues. Gearing is almost better than when it was new. Gearbox fluid checked, nothing observed here and they said no need to change it either.

The Turbo on the car was changed around 2009 (Warranty job) and has appeared to be ok since.

At all other RPMS, regardless of temperature or gear it runs as it should.

If I accelerate with more power and past 2100/2200 RPM, no sign of any issues. Idle the engine runs smoothly.

Car is in for a new diagnostic next week. As it now is driving in excess of 110-115 km/h is very unpleasant when going flat/long uphills. At higher speed, i.e. 125-130km/h and over, smooth as a Persian carpet.

Any help/Tip appreciated! Thanks!

Plutoe

Have you swapped ECU's??

What happens when you disconnect the EGR??

Have you tested the injectors??

KHM

Hi there and thanks for your reply. As far as I know (not being a very MB techy person) Main ECU option has been tried or, they at least have replaced software and/or updated it while testing.

So I don't think it is related to this. Then of course I wonder, why would it cause a particular symptom to occur only in a certain RPM range.

EGR, funny you should ask. I think at one point this unit was changed. The car was for several years only used for very short distance driving. Also during winter. At one point it stopped/died, they had to change.. something. Think it might have been the EGR, at least I recall something about that.

Whatever it was, I do wonder if it was after this the jerking began but.. not entirely certain. What I can say is when accelerating/driving from idle RPM to 2100 RPM, right before it gears the mechanical sound comes and it jerks.

Past that.. it is gone.

As for injectors, no idea. Will ask when I take it in. But could they cause symptoms like those describe?Only at a given torque/RPM range? And not in any RPM range and/or on idle?

Cheers

KHM

Ok, so finally.. after years of annoyance the problem looks to have been identified and resolved.

Turned out to be related to the EGR (Exhaust Gas Recirculation) valve! Kinda ironic, as the part was changed on the car approx 4 yrs ago. I'd used it too little, the car died on me one day. The EGR was changed.

Ever since this took place I've had a lumpy, jerking symptom around a certain RPM. But it took some particular circumstances to really identify it.

The dealer ran diagnostics, from those it could look like it was the turbo. So they changed the turbo, but it didn't help. The technician who worked on the car checked the history and saw that the EGR had been changed. And that I started to report irregularities not long after.

More testing is needed, but this far it looks like they nailed it.

Tip to anyone else getting this problem: If your workshop runs diagnostics, this fault might not show up, all values might read normal. In my case the issue only manifested itself around 2100RPM, when the car geared from first to second, or when it ran at in a particular angle uphill.

So definitely pressure related, which is why the MB dealer thought it was related to the turbo.

Fingers crossed but.. looks like an X file is X no more

sar786

I have the same symptoms in my E280 CDI 2006. I thought maybe my Cat are blocked causing back pressure or my turbo actuator. Can you tell me how much the EGR Valve is and if its a big job to change?

KHM

Hi sar786

from what I was told EGR fault can actually camouflage itself, diagnostics either will not reveal what is really wrong OR point at something else. Like the turbo which in my case was ok. Now I have been driving a bit and all symptoms are gone! I do find quite a lot have been reporting similar issues and suspecting the EGR being the culprit.

One thing might be worth adding, a faulty EGR can produce a distinct sound under certain circumstances, especially at approx 2100RPM, when it gears from first to second.

As for prices, found an EGR for W211 on ebay for GBP85, retail supposedly around GBP350. When it comes to work, no idea, a guess would be anything from 2-4hrs?

sar786

Hi

Thanks for your reply. I shall try the egr valve hopefully I can solve the issue. If not will have to maybe look at the turbo actuator.

I can get egr valve for £200 brand new (brother has a auto parts shop).

Will update as soon as I have some news

sar786

Ok so I changed the egr today
Drives lot better
However the jerk is still there uphill

Not sure if it's exhaist related but when I parked up the engine very hot and I could hear the exhaust crackling even whilst the car was off and I could smell burning exhaist fumes from under the car in the middle

KHM

Hey there, well glad to hear there's been progress! As for the jerking, does it seem likely that, with the improvement post EGR change, that there is something else with the circuit it's connected to?

Then again it could be something entirely different of course.

As for the last part, I have no idea, perhaps something you should post in a separate thread?

sar786

Not sure...
Ex Mercedes mechanic suggested due to high mileage this may be related to injectors not functioning properly.