Engine will not rev above 3000rpm & gearbox will not kick down

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derekpayne

Active Member
Joined
Dec 17, 2011
Messages
77
Location
Torbay
Car
CLS 320 CDi 2008 "Facelift"
Hi

I have a CLS 320 2008 "facelift" model.

Today it decided to go into a sort of limp mode where it would not rev above 3000 rpm and the gearbox would not kick down.

I stopped, turned the engine off, removed the key for about 10 seconds and tried again and all was well. It has done this before a few times but it must be about 12 months since it last did it and removing the key sorted it then too. There is no sign of the engine management light.

Any ideas would be appreciated.

Cheers
 
Failing electro-plate (sensor plate) in the gearbox. Could continue for a long time with intermittent limp mode before failing completely, or might fail tomorrow.
Best to get the codes read using STAR/Xentry, any good indie should be able to sort it if it is failing.
 
Would that clear by cycling the IGN? I'd have thought the EML would come on as well?
I think the swirl flaps can stick a bit to start with as the inlet manifolds begin their slow blocking up
 
Computer says you've got a problem.

As the boys say, an icarsoft reader will tell you what the fault is, or an independent garage will plug its own reader in and tell you what the problem is, and scope out the solution.

Computer isn't always right. And sometimes you may have done something stupid which throws a false error code.

Nothing unique to Mercedes. It's modern car tech.

.
 
This happened to our other car recently. It's a manual so k/d wasn't an issue. Wouldn't rev over 3k and not enough power to get out of 3rd. No EML.So I parked up and had a cuppa. Restarted it and drove as normal down to my garage. They did a code check - nothing. He said it just happens. Treat it like a computer and turn it off and back on.
 
When I first got my S203 C270Cdi, it took a while to find (as 3k in top is 80+MPH) but I had exactly the same problem. Luckily the car had a warranty, some research on here and t'other side suggested MAF - and changing that completely cured the problem.
 
It happened again twice yesterday, cleared by turning off, pulling key, wait count to ten, restart and away we go.

Swirl flaps have been suggested before as I also have a problem sometimes rairly when I first start up go to accelerate and its as if someone keeps turning the ignition off and on a few time very quickly have kangaroo jerks then it clears and its fine, again no EML, the turbo actuator has also been suggested.

Any more thoughts would be appreciated as the two faults could be linked, the jerking fault I have tried with the gearbox in manual mode, sport or comfort and it makes no difference.

Cheers
 
It happened again twice yesterday, cleared by turning off, pulling key, wait count to ten, restart and away we go.

Swirl flaps have been suggested before as I also have a problem sometimes rairly when I first start up go to accelerate and its as if someone keeps turning the ignition off and on a few time very quickly have kangaroo jerks then it clears and its fine, again no EML, the turbo actuator has also been suggested.

Any more thoughts would be appreciated as the two faults could be linked, the jerking fault I have tried with the gearbox in manual mode, sport or comfort and it makes no difference.

Cheers
What mileage have you got buddy ?
 
The jerking has been mentioned as turbo actuator issues on the om642 , I remember reading about it when I had similar occasional jerking usually on a hot start , but my last issues like that were at 50k and I’m at 106k now .
If you are handy you could spend a couple of quid and put a 4.7k ohm resistor into the middle two terminals of the inlet port motor (£2 on eBay) , if this works it indicates an ilps motor/swirl flaps issues .
You could also take the actuator apart , mine had grey motor gunk (from the carbon brushes?) inside , I sprayed it clean and put some high temp grease on the worm gear drive inside . The actuators can suffer from a break in the four wires that sit on the outside of the board inside , check this when you open it .
You could also spray clean the tiny hole on the inside of the exhaust back pressure sensor that sits by the egr valve and the turbo
All free jobs (ish)
 
Exhaust back pressure sensor, swirl flaps, egr, turbo actuator , the gearbox can put the engine into limp mode , so don't always assume its an engine fault. You need a techy to look at live data and fault codes.
 
I have checked and there is a fault code P2A00 I have attched a pic here, I have cleared the fault and it hasn't come back yet. The car has done 140,000 miles so far. The symptoms to me are turbo related as there is no boost at all when you try to accelerate when the fault is present.
 

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I have checked and there is a fault code P2A00 I have attched a pic here, I have cleared the fault and it hasn't come back yet. The car has done 140,000 miles so far. The symptoms to me are turbo related as there is no boost at all when you try to accelerate when the fault is present.

You really need yo scan it with a Mercedes Benz specific scanner such as iCarsoft or MB Star itself.
 
Well you are at the stage of trying to find out what is going wrong,lets tackle the swirl flaps issue,have you checked that no oil is dripping from the turbo onto the flaps,this is simple to do,on your engine there are black plastic pipes joining into one where they meet the trubo right on top of your engine take the pipes off and inspect the seal,maybe buy a new one and fit it a easy diy job,the fault may well be the electro plate in your gearbox,has your car had a ATF oil change,how many miles has it done,at this point you have a decision to make,change ATF and hope it cures the fault,if it does not then you have wasted £200 having that done,the 7g box does not post faults in my experience until it goes wrong big time,of course have it put on star at a indy to see if there are any faults,I suppose the cost of around £60 to run the tests,lets assume it is the electro plate playing up,it is best to get your plate repaired as it can go straight back into the car and not need coding,there are two repairers neither anywhere near you, Valve Bodies Uk near Liverpool,also offer the whole package they will remove the electro plate and repair it if you can spend a day up there at least they used to,the other is ECU testing in Derbyshire,they will accept your electroplate by post and if nothing wrong only charge a test fee,I can only say that Valve Bodies have been excellent in the past,and the fact that they will do the whole job is in my view a plus,sorry for the long post.:oops:
 
I have checked and there is a fault code P2A00 I have attched a pic here, I have cleared the fault and it hasn't come back yet. The car has done 140,000 miles so far. The symptoms to me are turbo related as there is no boost at all when you try to accelerate when the fault is present.


Any form of limp home mode shuts down the turbo. Don't assume its the turbo. That o2 sensor won't be the problem either. You can disconnect it and the car will drive just the same , other than maybe a loss of 2mpg .
 
Yep , as above the O2 sensor went on my om642 (same as yours) with no limp home activation
 
My dads c320 cdi non dpf has just thrown a mil and no power. Rac plugged it in and say its swirl flaps. If they are stuck open would it still reduce power in limp mode or can we assume there stuck shut? Sorry for the thread hijack 👍.
 
The Computer knows what it thinks is the problem.

We can tell you a dozen horror stories of what might put a car into limp mode, but there's a billion quids worth of tech design in the OBD (On Board Diagnostic) systems which are built into your car.

Until you borrow a £20 code reader, or a £100 advanced code reader from a friend who's got one, or maybe even buy one off t'Net, use it, (and sell it back to the Net again) you won't know for sure.

Why do I labour the point? Because a decade ago my W220 S500L did it three times, and I thought I could just outguess the system. It wasn't an expensive problem - TBH I can't remember what it was now - maybe plugs?

On-board diagnostics - Wikipedia
 

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