High Revs and Loss of Power 350cdi

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stoutgoose

New Member
Joined
Sep 26, 2011
Messages
28
Location
Woking.
Car
2012 Mercedes Benz C207 E350CDI, L322 Range Rover.
Evening all.

I have recently purchased a 2012 facelift C207 E350cdi 7g+ 265bhp.

I have previously owned a 2011 W204 C350cdi pre-facelift model 231bhp and covered over 100k in it, so am familiar with the engine and regen process.

The new car has in the past week, twice gone into a strange mode. Revs increase to around 2000 before a gear change, and the car is dropping down into first when slowing or stopping. There is also a significant loss of power and even when the accelerator is pushed down, very little happens. On a road when the car would normally be in 7th, it is holding in 5th and will not change up when the flappy paddles are used.

There is no tell-tale hot rubber smell and lots of heat coming from the underside which usually signifies a regen occurring.

Earlier this week when it first happened I drove around for half an hour to let it do its thing, but it did not drop out of this mode. The following day it was back to normal. Same again this morning; all normal, however this evening it went back into strange mode, so I drove it onto the motorway and covered 40 miles at 60-65mph, yet this had no effect.

I had the car serviced last week and the gearbox oil and filter changed using a Mercedes service kit. Low ash oil used.

The car has covered 84k with 1 owner and a full history.

Any ideas?
 
I doubt it. They are a local garage I have used for years and have general diagnostic kit, but not STAR. The previous owner had it serviced with MB for the first two years, then used an aftermarket company, so again I'm hoping it has escaped any of the emissions tomfoolery that Mercedes are being accused of.
 
Probably need to get in on STAR to see what is happening with the live data
 
Yup, that's Monday's job. Luckily I have a Merc specialist with STAR nearby. Typical it had to happen over the weekend.
 
Sounds similar to what mine did at the weekend. First trip since it was serviced at a main agent. 33 mile trip to visit my parents: normal at first, then about half way through the journey the power vanished: it was revving up to 3000rpm before changing gear even with gentle acceleration and it seemed a struggle to get to 60mph. Not good for a 265bhp 3-litre diesel! It stayed that way until I arrived. But completely normal on the return trip.

Of course, the dealership claims that they haven't heard of anything like this previously. The car itself didn't throw up any error messages or lights and, when I got home, an ECU scan using Carly didn't reveal anything either.

Stoutgoose, please keep me informed of your investigations. I don't drive mine much so I'll have to start taking unnecessary journeys just to see if the problem comes back.
 
Thanks for your message. It’s a concern that yours didn’t throw up any fault codes. I will be using a specialist who has STAR and I hope he may have a better idea than the fitters at MB.
My previous C350 went into limp mode and it turned out to be something in the inlet manifold. It was 4 years old and MB covered most of the £1200 repair cost.
I’ll keep you posted.
 
Hi lads,
Will be interesting to know this answers as my CLS X218 has the same paranoid sometimes, took it to mercedes while back and after diagnosis nothing found.

Of what I been seeing it looks like the CAT particles filter, saying this because if I drive steady let's say for a week, then give it a push it tend to happen the same condition as you're describing, so my guess will be debris accumulating on the filter then with the push it tends to block or something. The suggestion from other research I've done in the past is to drive for 15 minutes with the engine at 2000 rpm.

Even on this situation I do not have a loss of power, if you're experiencing that it sounds like the car goes to limbo mode.
 
So this morning, driving to the specialist, the engine management warning light came on which is a first. The specialist diagnosed, using STAR, a faulty DPF pressure sensor, which was replaced.

They forced a regen using STAR and I have been told all is well. Cost £288 all in for the part plus 2 hours labour to diagnose, rectify and regen the problem.

The car has not yet gone into the 'ECO' stop/start mode (the ECO sign remains yellow), although I did have the windows open and aircon off which may have affected it.

I'm not entirely convinced; time will tell.
 
Thanks for the update. Fingers crossed that the new DPF pressure sensor fixes it for you.
 

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