My C240 Accelerates by it self
Thread Starter
Junior Member
Joined: May 2012
Posts: 15
Likes: 0
From: Orange County, CA
S500-(2003) & C240-(2001)
Okay I think my problem just became bigger....I wanted error code to point issue out well i got one...so i cleaned the throttle body, and drove it for a while, and on a way back home, the gears just stopped shifting..
This is probably separate issue or maybe add on on the original one i had. Now the car will not change gears, just first gear and I put it in drive and thats it will not change further. I can also do reverse but thats it so reverse and first gear.
On the display it does not show anything on the gears as it was before when i put it in drive it will indicate D, when i put it in Neutral it will indicate N, now nothing...
As soon as I stopped the car and turned it back on Check Engine popped up...
Not sure if this is kind of revealing adding to my previous acceleration issue or this is totally separate one. So i will now have to find OBDII to plug in and discover the error codes.
Any ideas guys? Looks like my luck ran out ... now I'm totally broken....
This is probably separate issue or maybe add on on the original one i had. Now the car will not change gears, just first gear and I put it in drive and thats it will not change further. I can also do reverse but thats it so reverse and first gear.
On the display it does not show anything on the gears as it was before when i put it in drive it will indicate D, when i put it in Neutral it will indicate N, now nothing...
As soon as I stopped the car and turned it back on Check Engine popped up...
Not sure if this is kind of revealing adding to my previous acceleration issue or this is totally separate one. So i will now have to find OBDII to plug in and discover the error codes.
Any ideas guys? Looks like my luck ran out ... now I'm totally broken....
MBWorld Fanatic!
Joined: Jun 2011
Posts: 1,494
Likes: 131
From: Cape town
not a merc
We can only tell if your two problems are related by looking at the fault codes, Anyway gearbox faults can cause the engine light to come on too,
Over fueling will not cause a car to accellerate, a petrol engines speed is purely goverened by air flow and not fuelling, when the mixtures are correct, more fuel cannot make it go faster, only more air with more fuel.
so rule out injecter faults. they will only cause misfires and poor idling.
I would like to see on a open road just how much your car accelerates by itself before slowing down and how u initiate the process, that would help to fix it.
I really think you should have a short test done on star diagnose not a generic OBD tester, they are not in depth enough for these tricky problems. Some ECU's have Event memory as well as fault memory which only star can retrieve. Also if there is a fault star diagnose will show us the engine parameters as the fault was logged. that way we can see things like throttle position and pedal position and engine speed and load as the fault occoured.
Over fueling will not cause a car to accellerate, a petrol engines speed is purely goverened by air flow and not fuelling, when the mixtures are correct, more fuel cannot make it go faster, only more air with more fuel.
so rule out injecter faults. they will only cause misfires and poor idling.
I would like to see on a open road just how much your car accelerates by itself before slowing down and how u initiate the process, that would help to fix it.
I really think you should have a short test done on star diagnose not a generic OBD tester, they are not in depth enough for these tricky problems. Some ECU's have Event memory as well as fault memory which only star can retrieve. Also if there is a fault star diagnose will show us the engine parameters as the fault was logged. that way we can see things like throttle position and pedal position and engine speed and load as the fault occoured.
Thread Starter
Junior Member
Joined: May 2012
Posts: 15
Likes: 0
From: Orange County, CA
S500-(2003) & C240-(2001)
Okay I will try to acquire STAR to read the logs, I will post the error codes as soon as i get the device.
And thanks again for your time and response. Its greatly appreciated!
And thanks again for your time and response. Its greatly appreciated!
Thread Starter
Junior Member
Joined: May 2012
Posts: 15
Likes: 0
From: Orange County, CA
S500-(2003) & C240-(2001)
Example/scenario: if I'm driving 40Milles per hour,and trying to break, the car will slow down to lets say 20-30Milles per hour and then will try to pick up on its own, so if i don't pressure the break and let it go to do its acceleration it will go about 2-4 seconds and up to 35milles per hour, and then it will go back to normal.
I hope this helps troubleshoot better or clarifies the issue. And like i said now i will try to find STAR so i can get the logs our and let you know.
Super Moderator
Joined: Jun 2008
Posts: 19,942
Likes: 192
From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Agree on Star & please take the pipe from the purge valve to the manifold & block it & see if it makes any difference.
Both MB & BMW can suffer partial engine runaway due to EECS faults - The EECS circuit provides both more fuel & air to the system.
I would like to see what the throttle plate is doing when this occurs & even a scanner with real time capability can trap that.
Both MB & BMW can suffer partial engine runaway due to EECS faults - The EECS circuit provides both more fuel & air to the system.
I would like to see what the throttle plate is doing when this occurs & even a scanner with real time capability can trap that.
