Serious Help Needed, E300TD

[Big_Jon]

Hi All,

Had the problem with my E300TD where it performs ok cool and then as soon as warm, loses performance, wont kick-down and is generally sick.

Definately NOT the MAF as have tried 2 brand new bosch units to no avail.

Any ideas???

Going into a very good indie-specialist tomorrow and I really am praying otherwise it will be going down the block.

 

[grober]

Faulty Crank Position Sensor? http://www.detali.ru/cat/oem_mb2.as...GM=717.446&CT=M&cat=19T&SID=15&SGR=120&SGN=04

 

[aka$h]

A crank sensor would genrally fail and cut the engine out.

Im sure Dieselman will have an idea.

 

[Dieselman]

Hmm...LOL..

If the MAF is definately good then there's not too much it can be.
I'd check the air and in particular water temp sensors followed by fuel sensor and shut off valve and fuel heater thermostat.

You can measure the sensors for resisitance or read the values using Daig, but try bypassing the fuel heater as a start.


Is it definately temperature dependant or is it running time and engine load. If so check there is a good supply from the tank, the strainer might be blocked.

You could check the strainer and heater using a vacuum gauge just before the pre-filter.

It won't be the crank sensor, the timing is purely mechanical.

What exactly do you mean by running poorly.? Low on power or running rough.?

 

[Big_Jon]

Definately temperature dependant.

Thanks for the advice on this, really appreciated.

Going in to mertech tomorrow and mick has all the diagnostic gear so fingers crossed.

 

[aka$h]

Hmm...LOL..

I think you should start A Dieselman's version of the haynes books.

 

[grober]

It won't be the crank sensor, the timing is purely mechanical.

Not saying you're wrong DM but what would happen if the crank sensor was going faulty when hot? Very common fault in petrols and tends to stop them dead in their tracks as Aka$h said --but what about in a diesel?--I assume its there for a reason- --I am assuming I have the correct engine here of course?

 

[aka$h]

Not saying you're wrong DM but what would happen if the crank sensor was going faulty when hot? Very common fault in petrols and tends to stop them dead in their tracks as Aka$h said --but what about in a diesel?--I assume its there for a reason- --I am assuming I have the correct engine here of course?

It will stop the diesel engine dead too. I had a faulty cranksensor on my last e300td, the car would cut off.

 

[Dieselman]

Yiddo, if the engine simply loses power and is very lethargic after about 5 minutes of running check the EGR valve is working as that will trip limp home after several minutes of running and revs rising and falling.

 

[Dieselman]

Not saying you're wrong DM but what would happen if the crank sensor was going faulty when hot?

They can stop the engine dead but don't go wrong anything like as much as a petrol engine due to running much cooler.
The problem the O/p has isn't stopping dead, but running badly, which the CKP can't do as the timing is mechanical, in addition the ECU takes it's primary engine speed signal from the sensor inside the fuel pump.

The CKP can be measured on Pin4 of the Diag socket, so is easy to check.

On a petrol engine the CKP is used as a timing reference so can cause all sorts of weird running faults.

 

[230K]

Hi

Is the rpm sensor the same as the crank position sensor?? This guy http://www.mbclub.co.uk/forums/showthread.php?t=65021 is having rough running at idle with a duff rpm sensor.

230K

 

[Big_Jon]

Yiddo, if the engine simply loses power and is very lethargic after about 5 minutes of running check the EGR valve is working as that will trip limp home after several minutes of running and revs rising and falling.

Genius!

We had a 320CDI that drove like it had a 2hp outboard running it.

We cleaned the EGR valve, popped it back in and bingo!

Hopefully that may help resolve it.

Thanks

 

[Dieselman]

Is the rpm sensor the same as the crank position sensor?? This guy http://www.mbclub.co.uk/forums/showthread.php?t=65021 is having rough running at idle with a duff rpm sensor.

Because his mechanical pump has electric idle control. If the CKP goes down the idle control is lost.

He doesn't have trouble when running.

 

[230K]

Thanks

Wasnt sure if rpm sensor was the same as crank position sensor.

Shows how little i know

Thanks

230k