W211 E55 - No engine braking / feels like in cruise control

[andyb4.5]

Hi,

I've got a strange problem surfacing on my 2004 W211 E55... it won't slow down! Driving at sensible speeds anything around or below 40mph, in C or S auto mode, the car just maintains its speed with no throttle input.

This is on level roads. Feels like it is in cruise control (but it isn't).

Previously engine braking used to occur & it would change down through the box. Now it just continues chugging along around 1100 rpm in whichever gear.

Its pretty unnerving & I'm having to use the brakes a lot more instead of just coming off the throttle.

Any ideas as to the potential culprit? It's got an occasional misfire, which I'm assuming is unrelated.

Any help would be much appreciated
Thanks
Andy

 

[Alps]

Hi Andy,

not sure what the problem could be , would be worth getting it diagnosed properl on star tho.

Alps

 

[Oli]

Hi Andy,

not sure what the problem could be , would be worth getting it diagnosed properl on star tho.

Alps

Agree with this, you don't want to leave that long and wear your brakes out, they arn't cheap to replace!!.

 

[TDE1]

Sticky throttle body valve? Had the same in mine couple of months back, new unit was required

 

[andyb4.5]

Will get it checked - thanks guys. Hopefully the brakes won't wear out that quickly - I console myself with the fact that some people have never heard of engine braking - throttle or brake & nothing in between

 

[st4]

You can always nock it into N in the mean time, better than driving it against the brakes.

 

[Oli]

You can always nock it into N in the mean time, better than driving it against the brakes.

Would that not be bad for the gearbox?.

 

[andyb4.5]

From the user manual: "To avoid damage to the transmission, never engage N while driving". Its booked in on Tuesday, so hopefully will be fixed then...

 

[andyb4.5]

Turns out it was the Throttle Control Motor that was playing up. According to the dealer a failure mode of that was a build up of additional pressure in the system that blew off a vacuum hose & caused the misfire, so the faults were related.

All fixed under Tier 1 warranty & car is running beautifully (& quickly) again

Thanks
Andy