Cant accelerate over 4500 rpm in kickdown
Thread Starter
Senior Member
Joined: Aug 2002
Posts: 308
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From: UK
Cant accelerate over 4500 rpm in kickdown
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
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
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Thread Starter
Senior Member
Joined: Aug 2002
Posts: 308
Likes: 0
From: UK
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.
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.
