Unhappy W211 E320CDI

[Blobcat]

Hi All,

A "short" 286 mile round trip for me yesterday, on the way back I accelerated hard away onto the main road and received 3 sharp judders like kangaroo petrol in a manual. It then cleared for a couple of seconds and did the same thing again. Following that I had no kick down or turbo so pulled in at a layby and switched off. I then drove it back home and the kick down and turbo were working to some extent although nothing like I am normally used to.

Just before I arrived home I called Mobilo, they sent out a service van (~40minutes) and ran a test on the car. Quite a few errors logged O2 sensor and turbo waste-gate were the main issues. Ran a test on the waste-gate and it was working perfectly He thought that because of the O2 sensor fail it went into limp mode, he didn't reset the errors so that the garage can see them today.

One impressive thing that I didn't know that Star could do was do a compression test! I don't know how it does it but wonder if it is the injectors that do the measurements of the back pressure?

I've taken it into my dealer today and am currently in a Fiesta

 

[rpe2]

Was it showing cylinder compression, or turbo boost pressure?

 

[Blobcat]

Was it showing cylinder compression, or turbo boost pressure?

Cylinder compression

 

[Cole@MBS]

Is been going for a while Russ!!

http://forums.mercedesclub.org.uk/showthread.php?t=41647

 

[Blobcat]

Is been going for a while Russ!!

http://forums.mercedesclub.org.uk/showthread.php?t=41647

I'd forgotten about the O2 sensor failing when you did a code read last year. I presume that caused the limp mode, would that also cause the waste-gate fault?

 

[television]

I can only presume that if the O2 sensor failed completely the engine management would be along way out,,what way does it fail,,in one way it would enrich the mixture, in the other way it would weaken it, and I think that this is the case here,,if the engine was too rich it would still run but be very smokey. see what they say in September when it comes back

 

[Blobcat]

I called the service manager tonight and they have a new turbo on order to be fitted tomorrow (thanks for warranty...). The Mobilo tech tested the waste-gate on Star and it appeared to be working so not entirely sure why they have changed the turbo.

I expect they will also be changing the O2 sensor although I didn't ask about that.

If it doesn't arrive tomorrow morning they have another E Class I can use so at least I will be out of the Fiesta.

 

[Alex Crow]

the compression test simply uses crank sensor generated data. i`ll try and keep it simple.......

the crank sensor is able to give very accurate values for crank speed, if you look at the ring gear you will see approx 80 or more teeth. each tooth will produce a voltage spike in the cps read by the ecu. so the ecu can gauge crank speed upto (approx!) 80x per revolution, clever and fast stuff huh? the ecu can use this info to assess the crank acceleration produced by each power stroke - it uses this for smooth running correction on the cdi engines.

ok so far? the compression test simply gives cranking rpm for each cylinder generated by this cps analysis. the test results quote a speed in rpm for each cylinder, which is indicative of the compression of the relevant cylinder assuming other mechanical losses are equal. the actual values will vary according to battery condition and engine temperature etc, but the point of the test is to compare values and ensure they are within a given tolerance of each other.

i think MB have changed a lot of the variable vane turbos, any knowledge of this malcolm?

 

[television]

i think MB have changed a lot of the variable vane turbos, any knowledge of this malcolm?

You are ahead of me on the Alexander, and your knowledge here is far better than mine

 

[Blobcat]

i think MB have changed a lot of the variable vane turbos, any knowledge of this malcolm?

Yes I think they have, the service manager did say that had changed a few and Cole has also confirmed the same.

I've called the dealer twice today for an update and just been informed that they are fitting the turbo at the moment.

 

[Blobcat]

The good news is that a new turbo was fitted yesterday, the bad news is that the Comand unit was stolen over night whilst it was at the dealers :-(, so I don't expect to see the car for a couple of weeks until a new unit can be fitted.

 

[rpe2]

Jeez. Sorry to hear that.

I'm looking to retro fit comand so I'll keep an eye out for yours on ebay:wink:

 

[psmart]

Bad luck all round, hope the car comes back in tip top shape, but you might forever be finding little pieces of glass!

What is crazy is that Mercedes dont one-time-code the COMAND system to the vehicle, such as in the ECU or keys. Easily done and they could hide the uProcessor in an extremely hard part of the COMAND assembly to prevent it being economical to extract the old uProcessor and install a new one.

Its lucky you didnt have the 420... 2 Turbos to go wrong, they had issues from the 270 onwards with Turbo's! I know they have gone to electrical actuators instead of vacuum controlled actuators, but it seems odd that Garrett havent got them sorted by now (> 10 years)! Could it be a red herring that the turbo has gone down, or some kind of combustion wave front design fault damaging the vanes?

 

[rpe2]

Sam Unit know more about this.

By all accounts a result of the wastegate being made of a different composition to the turbo itself, and the 2 just don't get on..

 

[Blobcat]

Bad luck all round, hope the car comes back in tip top shape, but you might forever be finding little pieces of glass!

What is crazy is that Mercedes dont one-time-code the COMAND system to the vehicle, such as in the ECU or keys. Easily done and they could hide the uProcessor in an extremely hard part of the COMAND assembly to prevent it being economical to extract the old uProcessor and install a new one.

I know what you mean, I've changed the control units of Motorola radios and even taken off the surface mount chips to try to clear the one time code that has been blown into them. I didn't have any luck at that and I think the Comand units should be the same.

 

[Alex Crow]

the turbo issue is with cdi3 on motors with varable vane boost regulation. older designs used the tried and tested wastegate system with vacuum control and rarely went wrong, only occasional vacuum realated problems which are relatively cheap and easy to fix. the variable vane system is great in theory with more accurate boost control and a more efficient turbo and housing design generally. the vanes are all linked together within the turbo with an annular ring which is rotated by the built in servomotor to regulate turbine speed and, consequently, boost pressure.

the problem is that the vanes and mechanism tend to stick when hot and under load, often only infrequently and briefly. when this happens manifold pressure excedes the max permissible amount and the ecu triggers emergency program, or `epc`, and severely limits torque and rpm. typically when tested with das in workshop scenarios the regulation is fault free, also cdi never logs eg `y100/1 position blocked` or anything to tell the technician that the mechanism could not be moved (unlike the m55 positioner motor on the manifold flaps - they will always log codes to say when the servo/linkage jammed). the only clue is the code saying b5/1 signal voltage too high, ie charge pressure exceded the max allowable.

we have seen a few now and expect to see more.

 

[rpe2]

Excellent explanation, thank you Alexander.

My 2004 E320CDI is suffering, feels at times like a manual car that has been left in too high a gear.

Saving hard for a new turbo as I have been advised that sending for a re-con won't solve the inherent problem.

 

[Cole@MBS]

You have a differnet turbo Richard to the one A/P replied to, Again, a perfect write up!!

 

[rpe2]

Thanks Colin,

In need of correction as per usual...:Oops:

Cheers

 

[psmart]

the turbo issue is with cdi3 on motors with varable vane boost regulation. older designs used the tried and tested wastegate system with vacuum control and rarely went wrong, only occasional vacuum realated problems which are relatively cheap and easy to fix. the variable vane system is great in theory with more accurate boost control and a more efficient turbo and housing design generally. the vanes are all linked together within the turbo with an annular ring which is rotated by the built in servomotor to regulate turbine speed and, consequently, boost pressure.

the problem is that the vanes and mechanism tend to stick when hot and under load, often only infrequently and briefly. when this happens manifold pressure excedes the max permissible amount and the ecu triggers emergency program, or `epc`, and severely limits torque and rpm. typically when tested with das in workshop scenarios the regulation is fault free, also cdi never logs eg `y100/1 position blocked` or anything to tell the technician that the mechanism could not be moved (unlike the m55 positioner motor on the manifold flaps - they will always log codes to say when the servo/linkage jammed). the only clue is the code saying b5/1 signal voltage too high, ie charge pressure exceded the max allowable.

we have seen a few now and expect to see more.

On the CDI2 engines you also have VNT, but is controlled by vacuum regulated by a BPCVT valve, which in turn is regulated by current control. There is a wastegate but only for overboost (ie more of a dump valve). These also suffered failures and when I replaced mine, it sounded a similar common fault, although not explained as well as you've put it.