SL Boy

I have recently bought a used SLK32 which I like immensely but it has one annoying fault - at least I assume its a fault. I floor the accelerator into kickdown mode and there is a huge surge of acceleration as you would expect but only up to about 4500 rpm at which point the car refuses to go up to the red line or change up to the next gear.

The "juddering" effect is similar to that when reaching the 155 mph rev limiter in top gear.

Is this normal or is it actually hitting the rev limiter which perhaps is adjusted too low or does it indicate a more serious fault.

all help welcome....

thanks

vraa

I think it's due to some kinda improper coding.
I'd ask the dealer to reflash the ECU.

MidniteBluBenz

Thats definetly not normal. I'd take that to the dealership and get it checked.

What octane fuel do you put in it?

SL Boy

Thanks for your replies.

I use 95 Octane fuel. Used to have a 230K SLK and used the same fuel with no problems.

Trekman

sound like your supercharger has gone bad.... have the dealer look at it

Jon Winter

Throttle actuator or Temp sensor

Jon Winter

I'm sorry look at the innercooler pump also. Does the car runs fine until you step on the gass hard?

SL Boy

Yes Jon, runs fine under all other conditions. Will get it checked.

SL Boy

Well it has taken me all this time to sort the problem as it didnt happen at all when the outside air temperature dropped below about 25 deg C which of course it did in the UK at the end of August.

With June temperatures above 25 deg again, problem returned but has now been cured.

There is a water cooling jacket around the supercharger and an auxiliary water pump to redirect the cooling system water through this jacket at air temperatures greater than about 25 deg. The pump had started to fail and blown its in-line fuse. As a precautionary measure when the uncooled supercharger reached a certain temperature the ignition was automatically retarding to stop any damage occuring.

So new pump and fuse fitted - problem solved.

Nice to know that Mercedes/AMG engineering introduced a failsafe process here to stop major damage and expense.