C250TDI Auto - Gearbox problem?

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paulfoel

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Jul 14, 2003
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Only happens some of the time - it seems to be anoterh time you'll drive the car and it'll be OK.

Problem is:-

Car won't go over 70mph and seems pretty sluggish.

If you kickdown or manually change gear (not at 70mph) the engine revs increase but the speed remains the same. Weird.

Of course, when its running OK it accelerates easily past 70mph and kicks down, accelearates OK in lower gears...

Anyone got any ideas ?
 
The gearbox isn't the issue, it'll be the ECU dropping the turbo so the engine can't produce enough power.
Possible MAP sensor but really needs the codes read.
 
Dieselman said:
The gearbox isn't the issue, it'll be the ECU dropping the turbo so the engine can't produce enough power.
Possible MAP sensor but really needs the codes read.

MAP sensor?

I take it you mean Merc dealer to do the diag?
 
Manifold Absolute Pressure. Boost sensor to you and I.

Any independant will be able to read the codes but it's probably cheaper to just swap the sensor.

There isn't a lot more in the 250 TD electronics that goes wrong.
 
Dieselman said:
Manifold Absolute Pressure. Boost sensor to you and I.

Any independant will be able to read the codes but it's probably cheaper to just swap the sensor.

There isn't a lot more in the 250 TD electronics that goes wrong.

I see. So the MAP sensor tells the ECU when to kick in with the turbo?

Hmm. So the consensus seems to be thats what the problem is with mine ?
How comes I can't accelerate without a turbo then? I've driven non-turbo diesesl in the past and although not great they can still accelerate !
 
paulfoel said:
I see. So the MAP sensor tells the ECU when to kick in with the turbo?
No the MAP sensor reports the boost pressure to the ECU so it increases fuelling accordingly.


paulfoel said:
Hmm. So the consensus seems to be thats what the problem is with mine ?
How comes I can't accelerate without a turbo then? I've driven non-turbo diesesl in the past and although not great they can still accelerate !

Gearing and fuelling. The gears are too high for accelleration and the fuelling isn't being increased due to being in limp home mode.
 

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