hi guys and girls
i recently purchased a slk at a auction and it wont rev pass 300 revs any ideas. it has done 45000 miles since new.

regards kevin

 

Hi,
Likely it is in "Limp Home" mode.
Get the OBD (On Board Diagnostic) codes read.
Come back with the codes.
This will point to the problem.
230/320, Man/.Auto. Year? 45k is no distrance for one of these vehicles IF it has been regularly serviced (i.e., oil change)
What does the ASSYST (Service Counter) readout state?
As a long shot disconnect the battery and leave for 10 mins or so then reconnect. Just might make a difference. NB., Ensure you have your radio code otrherwise you will end up with another problem!!
Do you mind me asking what you paid?
Stuart

 

yeah i don't see any reason why it shouldn't rev over 3000. take it to the dealership and have it check out.

 

hi
i paid 6k for it how do i get the obd codes.

kevin

 

Hi,
You didn't provide year details etc.
Good buy subject to whatever is currently wrong.
You need a scanner. Year makes a difference what type.
Scanners (at least ones that can do more than just give you the code cost circa £150 and many are available on eBay.
However most garages and especially dealerships will read the codes but will charge about £25.
Simply plug into the diagnostics port and turn on.
You get codes like P0170. This means that there is a fault in the emmissions system caused by the MAF being out of range.
You didn't state whether your Yellow engine light is ON?
If it is not check that it illuminates when you first turn the ignition ON.

Mercedes are very robust but resolving problems can be tedious because of the proprietary electronics.
Once you have the codes come back and we will try to indicate what to do next.

You didn't state but if it is a 230 then there are a whole load of problems that i am not famiuliar with linked to the supercharger (I have a V6) but the codes will indicate the direction to go in.
Please also expand your symptoms.

For instance will it not go above 3000 RPM......
When stationary. Out of gear?
On the road in 1st gear.
On the road 2nd gear.
Under any condition.
What happens once it reaches the 3000 limit? Does it cough and splutter or is it just unwilling to go further?
Where is the accelerator pedal when it is going at 3000 RPM. Fully down? or does the pedal just not seem to be connected from say quarter throttle position. There is no throttle cable on the SLK. It is an electronic (fly by wire) system.

There are a whole load of safety systems. For instance the engine will not rev above 4000? when stationery / out of gear to prevent engine damage.
The engine speed is limited if emmissions limits are threatened (limp home)
There is a rev limiter to limit engine overspeed...set at 6000 or so.
There is a speed limiter. Maybe this is on (control on LH steering colum stalk) and you have assumed that the engine is at fault when in fact the speed limiter is set lets say for 30mph.
etc.etc.
Did you disconnect the battery?
Stuart

 

Hey Kevin was your car a 230? was it the speed limiter?

 

So how have you got on?
Stuart

 

Im guessing the MAF needs cleaning or replacing

Bazzle

 

[B]Hi I have merc (w203) I have taken to Mercedes specialist because my car was not going over 3000 revs and also engine management light was on, put it on star machine came up with Dpf full, had Dpf cleaned and degeneration process drove car back superb, later that day back into limpmode this time Mercedes told me it's an O2 sensor upstream so paid 400 Inc labour and got it fitted still sane problem took it back said it's could be the egr which is sticking so replaced egrdrove it home later that night same problem not goin over 3000 revs now you can understand how frustrated I'm getting so I take car back to merceds specialist put it on ramp the changed the turbo actuator still no look I really am not happy what could be causing the problem for the car to go into limp home mode.please help [/B