E350 CDI w212 high revs/gear changes

[Shed9098]

Hello all,

I wonder if anyone can advise and would be grateful for their input on the issue that I am currently facing.

I have a w212 e350 Cdi 2011 saloon - Auto. No error or codes for fault.

Out of the blue the car runs at higher idle and in turn changes gear more than the normal revs to do so. It is a very much unusual problem, not only I am finding it frustrating but unable to diagnose the issue. I have been told by Merc Dealership, they unable to create the problem and as there are no errors/codes unable to diagnose.

The issue happens now and then. After the engine warms up the gear changes will be smooth, and will be changing using the correct revs. However suddenly the revs will be higher than normal (800 like a cold start) and this then runs a chain of events. The car will change gears but higher revs are needed to and in turn will not cause overheating but excess heat under the bonnet. This is recognised when parked up. However some days the car will then suddenly drop revs and run as normal.

The best way I can describe it is like sticky revs, and the revs behave in a way that more revs are required for gear changes, and not running efficienty as it should do. There are no codes from the transmission/not stalling. Sometimes it feels like something is clogged and causing the issue and therefore I would put the gas pedal on the floor to clear and and sometimes it goes back to behaving normal. Not sure if it's is a clogged up EGR Valve.

Sorry if I haven't been clear but it's an unusual problem and finding it difficult to find the culprit.

Any advise or help will be really appreciated.

 

[st13phil]

Does this happen only once the engine is fully warmed up and you've been driving for a while? If so, it sounds like it's the DPF regen cycle running.

 

[Bri]

Sounds like DPF regen cycle to me to, but it should only last for around 20 minutes then gear changes and revs return to normal.
With my e350 this usual happens around every 1000 miles.

 

[Peter103]

If you normally do a lot of short stop start driving in town, as opposed to longish m/way runs where the engine runs hotter and at higher revs for longer periods, it will regenerate more often. During regeneration when stopped, tickover will be around 800 rpm, normally 600. Until regen, is complete. Next time this happens switch off and lightly touch the exhaust tips at rear, if they are too hot to touch it's regenerating, if they are only warm or cold that's normal.

 

[gIzzE]

As others have said, DPF regen.

Is your temp getting to 90ºc and sticking there no matter what?
If it fluctuating at all you may be stuck with the car trying to regen and not able to.

 

[Mr Filipov]

Learn to embrace the DPF regens haha. With short runs they will happen every 250 ish miles. Try to keep driving while it completes it. Can be stopped once or twice by turning off the car if at the end of a journey, but generally let it do its thing. You do not want a blocked DPF.

Oh and forgot to say, don’t take it as a pop at yourself, but everyone in general needs to do some research into what they are buying as well as being told by dealers. Both of these sadly do not happen often enough.

 

[OJLane]

I was really worried when I first got mine, a definite learning curve! Was really bad when the oil cooler seal went and there was a pool of oil just under the DPF, thought the car was on fire there was so much smoke! :-D

 

[Shed9098]

I am grateful for all replies and appears you guys have resolved my issue as being the DPF regenerating.

I tend to do motorway miles - 500 miles a week, and it happens on the motorway. Also it may happen once or twice a month and this DPF cycle happens out of the blue less so on motorway driving. The engine temp never fluctuates and stays at 90 even when it is doing its thing.

As most said the DPF regenerating, it's normal I guess but it appears After the DPF cycle finishes and I stop my journey I get concerned how much heat it produces under the bonnet. First diesal car for me so newbie.

Shall I use additives to clean the DPF or get the DPF cleaned? The car has done 185,000 so i am wondering if the DPF is getting clogged. Thanks again for all your input.