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Om642 sometimes loses power

CLS320CD1

New Member
Joined
Sep 22, 2024
Messages
7
Location
Finland
Car
CLS 320 CDI
Hello, my w219 cls320cdi sometimes randomly loses power, during kickdown revs do go up but it accelerates poorly and doesn’t really have any power. It doesn’t go into limp mode and the problem does disappear after driving around and giving full throttle for a while. Almost seems like something is blocked, maybe🤔
Any ideas?
 
Hello, my w219 cls320cdi sometimes randomly loses power, during kickdown revs do go up but it accelerates poorly and doesn’t really have any power. It doesn’t go into limp mode and the problem does disappear after driving around and giving full throttle for a while. Almost seems like something is blocked, maybe🤔
Any ideas?
The car will probably have fault codes that will indicate where to start .
 
Code P0299 (Turbocharger/Supercharger A Underboost Condition)
The turbo actuator is new, no leaks or cracks in pipes. Charge pipe o-rings(green,black) and Y-pipe orange seals have been changed.
Could a faulty EGR or swirl flap failure be the cause?
 
You need more info than just a code.

Replacing just the actuator doesn't often work so I suspect its something to do with that.
 
Hello, my w219 cls320cdi sometimes randomly loses power, during kickdown revs do go up but it accelerates poorly and doesn’t really have any power. It doesn’t go into limp mode and the problem does disappear after driving around and giving full throttle for a while. Almost seems like something is blocked, maybe🤔
Any ideas?
My faulty egr gave similar symptoms - felt like limp mode but no lights then was fine after a restart. It also made the gearbox very jerky at low speeds, which i only realised was due to the egr valve once it was fixed.
 
My faulty egr gave similar symptoms - felt like limp mode but no lights then was fine after a restart. It also made the gearbox very jerky at low speeds, which i only realised was due to the egr valve once it was fixed.
How did you fix the issue? Just by cleaning the egr?
 
How did you fix the issue? Just by cleaning the egr?
I needs proper diagnosis. Cleaning an electronic EGR wont fix anything long term. The old fashioned EGR valves can be cleaned and that works well.

I would do a smoke test to be sure of any boost leaks first. Then I would re-set all the adaptation data and drive it some distance to see what happens.
 
Egr valve cleaned which was really sooted up, pcv valve replaced for the new version, Engine works normal when coldstarting, problem usually occurs after car has been shutdown for about an hour. I will try to put a 4.7k resistor into the swirlflap. Still no fault codes. Very weird fault because the car works totally normal most of the time. Any ideas?
 
Egr valve cleaned which was really sooted up, pcv valve replaced for the new version, Engine works normal when coldstarting, problem usually occurs after car has been shutdown for about an hour. I will try to put a 4.7k resistor into the swirlflap. Still no fault codes. Very weird fault because the car works totally normal most of the time. Any ideas?
Get it scanned by Star and then sort out the issue. It's the cheapest way overall.
 
What does the user manual say ?
 
Well this is new😳
Does anyone know the partnumber or what the part is called?IMG_5560.jpeg
 

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I've changed these large intercooler pipes on one of my W212s - one of them is cheap from MB and yet the other side is obscenely expensive. I tried a Gates replacement but it arrived looking used/awful quality. Could just be bad luck.

I'd change both personally as they tend to weep from the seals even if you don't have a tear. Relatively easy DIY if you're happy getting the car onto axle stands and removing the front tray. Bit cold for it though!
 
If the intercooler pipes are in good condition, you can buy the seals from Merc for a few quid 👍

Teddy, I recall your original pipe was worse for wear.
 
Looks like that one has big tear in it!

Yes I ended up changing the cheaper one completely, and then just doing the seals on the other one, but then completely wrapping it in high quality silicone tape multiple times. A bit ugly but pretty sure it's less likely to have issues than a new pipe!
 
It certainly looks like a split in the intercooler connection hose.
It happened to me around a year ago.
Not too difficult to change.
 
Looks like that one has big tear in it!

Yes I ended up changing the cheaper one completely, and then just doing the seals on the other one, but then completely wrapping it in high quality silicone tape multiple times. A bit ugly but pretty sure it's less likely to have issues than a new pipe!
I was on my mobile so didn't see that! A bit of a bummer.
 

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