C250TDI Auto - Sluggish - wont 'kickdown'

[paulfoel]

I've been thinking somethings up for a while...

Took it out for a drive tonight on quiet roads. Anyway, it looks like the auto box is refusing to kick down whatever... Never really noticed it too much before but if I remember it changes down if you ram your foot down.

At the moment, its just lumbering along in the same gear. Weird....

I tried fiddling with the S/W switch (Standard/Winter) to see if was that. (Wonder my litle boy has stood on it and jammed it in winter mode).

Does it do this in winter mode? (i.e. not cange down)???

Any other ideas?

Weirdly, changing down manually (not a tiptronic ) doesnt do too much either.....

 

[Iain]

Have you tried the gearbox reset posted on an earlier thread

 

[Iain]

1. Get in your car.

2. Turn the key to the on position.(not start)

3. Press the accelerator to the floor with the key in the on position.

4. Hold the pedal to the floor for 5 secs. then turn the key to the off position. (Don't take the key out) then release the throttle.

5. Wait 2 mins for a full alignment.

6. Drive the car and see if it responds as it should.

 

[paulfoel]

1. Get in your car.

2. Turn the key to the on position.(not start)

3. Press the accelerator to the floor with the key in the on position.

4. Hold the pedal to the floor for 5 secs. then turn the key to the off position. (Don't take the key out) then release the throttle.

5. Wait 2 mins for a full alignment.

6. Drive the car and see if it responds as it should.

Never heard of it before. I'll give it a try tomorrow...

 

[paulfoel]

Never heard of it before. I'll give it a try tomorrow...

Actually, how do u know if its actually doing anything ???

 

[Iain]

Well, if it changes gear and kicks down as it should,then hey presto!
This came from a forum in the US and the majority of posters reported great results!

If not,perhaps book it in to your local indy and have the transmission fluid changed along with a new filter.

 

[television]

Well, if it changes gear and kicks down as it should,then hey presto!
This came from a forum in the US and the majority of posters reported great results!

If not,perhaps book it in to your local indy and have the transmission fluid changed along with a new filter.

Hard to see this being possible as electric gearboxes do not have any memory in their ECU, they are on MB cars whats known as key re set, that means with any malfunction,turning off the engine,and re starting clears any fault within the box,
The Gearbox ECU talks to the engine ECU and adapts to the driving style of the car. It cant be any other way, you drive down a fast road overtaking what you can,and hit a 30 limit, the car is a docile as ever and changes gear normally.
With the car at the start of this thread,its more than likely that the MAF is going down and engine performance is reduced, disconnect it and try the car, if it drives almost as normal, then it is the MAF.

Malcolm

 

[Doodle]

Except of course, that the C250 doesn't have an MAF.

Doesn't sound right, as a good squeeze on the throttle (generally to about 3/4) will normally see it change down one gear on mine, with the kickdown dropping another gear.

 

[Carlo]

Check the Electronic/pneumatic valve that regulates the turbo valve.
Don't know the name in English.
Those valves are a common problem.

 

[Dieselman]

Check the Electronic/pneumatic valve that regulates the turbo valve.
Don't know the name in English.
Those valves are a common problem.

The vacuum transducer.

Also check the MAP sensor. If the sensor doesn't see boost it won't fuel the engine up.

If the turbo has been dropped you should be able to see the linkage is relaxed. The transducer is the same as the one for the EGR valve so you could test with that.

 

[paulfoel]

Whats the MAF?

Hard to see this being possible as electric gearboxes do not have any memory in their ECU, they are on MB cars whats known as key re set, that means with any malfunction,turning off the engine,and re starting clears any fault within the box,
The Gearbox ECU talks to the engine ECU and adapts to the driving style of the car. It cant be any other way, you drive down a fast road overtaking what you can,and hit a 30 limit, the car is a docile as ever and changes gear normally.
With the car at the start of this thread,its more than likely that the MAF is going down and engine performance is reduced, disconnect it and try the car, if it drives almost as normal, then it is the MAF.

Malcolm

WTF is a MAF ???

 

[Harley Man]

A MAF is also known as a MAS, which is a Mass Airflow Sensor, it measures the volume of air the engine is drawing in so it can inject the correct amount of fuel to go with it.

Harley Man

 

[paulfoel]

Hmmm. Been in the dealer for a diagnostic and they can't find anything much wrong with it....

All they've suggested is to change the fuel filter....

I'm assuming a diagnostic would have picked up any problems with the turbo, ECU etc....

Bit of a waste of £30 for the diag (perhaps they wont charge me!)

 

[230K]

WTF is a MAF ???

Dont worry your C250 Turbodiesel doesnt have one.

230K

 

[paulfoel]

Hmmm. Been in the dealer for a diagnostic and they can't find anything much wrong with it....

All they've suggested is to change the fuel filter....

I'm assuming a diagnostic would have picked up any problems with the turbo, ECU etc....

Bit of a waste of £30 for the diag (perhaps they wont charge me!)

Changed the fuel filter and a few hoses etc - £72. Seems the same to me though but they reckon there aint a great deal wrong. Suggested some Diesel injector cleaner stuff....

 

[paulfoel]

Yes, thank you, useless Mercedes dealer - SG in Newport, South Wales.

Had someone come to look at the car today cos I'm selling and it played up again. Looks like there is something wrong after all !!!!!

How do I replace the MAP and the vacuum transducer ???

 

[paulfoel]

The vacuum transducer.

Also check the MAP sensor. If the sensor doesn't see boost it won't fuel the engine up.

If the turbo has been dropped you should be able to see the linkage is relaxed. The transducer is the same as the one for the EGR valve so you could test with that.

Sorry - could you explain in simple terms for me ???

OK. Basics. How do I test if either MAP sensor or Vacuum transducer is buggered?

Whats the EGR valve? Are you saying swap the transduver on the EGR valve with the the vacuum transducer?

What does the one on the EGR valve do?

Linkage relaxed ???

how much are replacement vacuum transducers and/or MAP sensors?

 

[LastMinute]

Whats the EGR valve?

Item 5 here. It's the valve that controls how much Exhaust Gas is Recirculated back into the intake manifold.

'The' vacuum transducer that Dieselman was referring to (in response to Carlo's suggestion) is the one on the turbocharger (item 5 here).

In both cases the transducer is a device that converts an air pressure input (from a vacuum line) into a mechanical output to control the position of a valve.

There's a diagram of the vacuum system here. I'm pretty sure it's the third one that applies to your car - though without any useful labels, it may not be much help.

 

[paulfoel]

Item 5 here. It's the valve that controls how much Exhaust Gas is Recirculated back into the intake manifold.

'The' vacuum transducer that Dieselman was referring to (in response to Carlo's suggestion) is the one on the turbocharger (item 5 here).

In both cases the transducer is a device that converts an air pressure input (from a vacuum line) into a mechanical output to control the position of a valve.

There's a diagram of the vacuum system here. I'm pretty sure it's the third one that applies to your car - though without any useful labels, it may not be much help.

So what does the first one do - control the turbo?

If I swap and say the one I put on the EGR is knacked, whats going to happen?

Are these valves serviceable at all?

 

[paulfoel]

Would this cause a problem? Its the connector for the turbo pipe that lies across the top of the engine block and attached to the manifold.