W204 C220cdi Loss of Power Under Load

[MBLOVERMCR]

Hi everyone,

I have a 2013 c220cdi manual gearbox - 105k miles, mostly motorway at 65-75.

I’ve been struggling with a loss of power since August last year. The issue happens when I put my foot down in 6th gear and the engine moves through 2,000 - 3,500+rpm. You know yourself when something is not quite right and there’s a bit of a flat spot somewhere in that range; if I keep my foot down past 3,500rpm the car goes into limp mode.

So far I have had the actuator and both intercooler hoses replaced but the problem persists. The car is serviced each year and is looked after. It just does a lot of miles on the motorway and I set the speed limiter to 65-75.

My gut tells me it’s something to do with the turbo unit. Maybe it isn’t regulating properly and there’s a boost issue which the ecu doesn’t like?
I drive in Europe (Germany) a few times each year so it would be nice if I could floor it in 6th without the engine failing. Here in England, driving every day, I’m terrified of the accelerator pedal at the minute. I love the car and don’t want to get rid but the garages I’ve used have been tinkering for 6 months and not diagnosed it.
Maybe one of you can help? Sometimes it’s about asking the right questions as well, which I don’t think the garage is doing.
The garage say there is only a boost fault showing on the machine but when the turbo is tested the boost levels are consistent.

Does anyone have any ideas what it could be or how to diagnose the fault?

 

[whitenemesis]

Does anyone have any ideas what it could be or how to diagnose the fault?

The obvious answer is the get any fault codes read using STAR. An experienced indie should be able to diagnose relatively cheaply.
Who services the car routinely?
Has it had any software updates applied recently (August last year)?

 

[MBLOVERMCR]

The obvious answer is the get any fault codes read using STAR. An experienced indie should be able to diagnose relatively cheaply.
Who services the car routinely?
Has it had any software updates applied recently (August last year)?

I thought it would be as simple as that. I know they’re reading the faults but it’s not leading to a diagnosis. The actuator was only replaced based off of my description of the issue - there may have been a second fault which the actuator repair does appear to have resolved. But this loss of power and engine mode trip appears no closer to being resolved. Surely the car can’t be on its last legs? She’s done the miles but barely everseen high revs.
It’s an independent Mercedes specialist in Manchester investigating the power loss and there’s a garage nearby who do the servicing, family friend, used him for almost 20 years so I’m happy with that part.
Not sure about the specialist though. They first diagnosed a split intercooler hose - even though it was evident that both hoses were split. I diagnosed the second damaged hose myself when I was inspecting my new hose - huge split, visible from space. No idea how it was missed but it’s a concerning oversight from them.
It had a software update from Mercedes a couple of years ago and everything was fine until the last six months.
I’m stuck because I’m in their hands entirely. The repairs are being arranged through Motoreasy (after market warranty company) and they won’t send it to a Mercedes main dealer.

 

[classiccarzone]

Did you get this sorted?. If not its sounds like an inlet manifold leak. Usually the bottom bolt second from the front. Usually drops into the under tray.
You will need a scope to look in at it. Usually a deposit of black oil/sludge can be seen, having dropped on to the oil cooler

 

[MBLOVERMCR]

Did you get this sorted?. If not its sounds like an inlet manifold leak. Usually the bottom bolt second from the front. Usually drops into the under tray.
You will need a scope to look in at it. Usually a deposit of black oil/sludge can be seen, having dropped on to the oil cooler

Not sorted. The last Mercedes specialist garage I went to said there was a stored error code stating pressure error on low pressure side of the turbo. They have no idea how to progress as all the hoses and pipes look good, and the actuator was changed recently.

It’s weird that you bring up the manifold though as I swear I can hear a bit of a rasp under acceleration.

Other than that I thought the most likely culprit was the turbo vanes sticking. My daily commute for the last 12 months was 50 miles each way and I spent it with the speed limiter set to 70. So I thought maybe the prolonged periods sitting at exactly 70 had caused the turbo vanes to stick a bit.

I’m going to try and get it into merc. I’ve had an after market warranty on it so they’ve been arranging the garage visits. They’ve told me to try and sort it myself and then get back to them. I wouldn’t recommend them.

 

[classiccarzone]

It has all the signs of an inlet manifold leak.
Prior to I changing the inlet manifold it had precisely the same characteristics as yours. Have a look at this youtube video

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