W210 E320 CDI engine switching to emergency run mode

[Nobby Clarke]

I have a E320 CDI with 130,000 km on the clock. Recently and unpredictably it has started to switch to emergency run mode: no kick down, does not go over 3000 rpm, lots of black smoke. Then when I stop and switch off the engine and restart the problem has gone away. I recently had a service and the diagnosed error code was a defective air mass meter. This was replaced and I had no problem for the next 1000 km or so. Yesterday, however, the problem re-occured. Anybody any ideas what it might be...?? Thanks

 

[television]

Welcome to the forum Nobby, I think it is a faulty MAS do you know where it was purchased,, Unplug it and see if the car runs better

 

[Dieselman]

Probably either the EGR valve sticking, the resonance flaps jammed or linkage come undone or blocked Cat on that order.

 

[BlackC55]

Seconded

 

[Nobby Clarke]

Dieselman, thanks for your reply. I have a horrible suspicion that it might be a blocked cat. I live in Germany and I don't know if you have heard but there have been problems with retro fitted diesel particle filters. I had one fitted last July (thought I was being a good citizen thinking of the environment!) however, it was found that some filters (including for my car) were not efficient and also some affected engine performance. They have been withdrawn from the market. Am now waiting for an improved replacement.

Anyway in the meantime will check the EGR and resonance flap valve.

 

[Dieselman]

My personal belief is that particulate filters are ineffective and a waste of time and money.
They have come about because for the unwarranted fear of diesel particulates.
This has come about as a result of media disinformation as opposed to proper scientific study.

Firstly a diesel doesn't emit much in the way of particulate matter, but what it does is visible, so becomes easily targeted.

Secondly the PM10 particulates can't pass through the lung wall into the bloodstream so don't cause problems anyway.

It is true that diesels emit more PM10 than petrol engines but in turn petrols emit more PM2.5 which are fine enough to pass into the bloodstream.
Diesels emit more particulates BY MASS than petrols but in turn petrols emit more particulates BY VOLUME than diesel.

In addition I've never quite understood how the SCR method of particulate filter regeneration can be particulate free.
It just stores them up and dumps them in one big cloud instead of continual relaese.
I don't see the point and they are definately detrimental to the peformance of the engine.

I would avoid a car with a particulate filter given the option.

 

[Dieselman]

Nobby
Try fitting a pressure gauge to the exhaust after the turbo, it will tell all if the cat or filter is blocked.

You can get special screw in fastenings to pass through a drilled hole from fixing and fastening suppliers.

 

[television]

For me reading that it key cleared, I do not see how it can be the exhaust of flaps

 

[Dieselman]

Unless they just flop back as a result of the engine stopping.

My first bet is still EGR valve though.

 

[television]

Unless they just flop back as a result of the engine stopping.

My first bet is still EGR valve though.

Yes true, is there no way the one can just remove the pipe from the inlet end, and try and blow through it, or from the output of the valve itself for if you could it would be open.

 

[Dieselman]

Sure, but if the valve is sticky it will just fail again once it opens next time.

 

[Nobby Clarke]

Just been to my local mechanic (Mercedes "meister"), who says that a faulty EGR valve should show up on the diagnostics. Have an appointment tomorrow morning for him to have a closer look. A blocked particle filter is also possible although have done about 15,000 km since it was fitted. Thanks for all your comments and suggestions.

 

[Dieselman]

The EGR valve operation is monitored by the MAF. There is no independent monitoring of it's operation.

So if the ECU thinks the valve is closed but it's not, this throws out the MAF reading so reports faulty MAF, not EGR valve.

 

[ceejay]

I had exactly the same symptoms on my E320cdi, usually when starting from cold. Went on doing it occasionally for some while until finally stuck permanently in "limp mode" - fault was the resonance flaps sticking which eventually made the control linkage pop off, exactly as DM described. It needed a new link since the clip/fitting on the end actually broke.

Chris

 

[Nobby Clarke]

Next episode: This morning was again by the mechanic. Changed the air filter as it was pretty dirty and showing red on the indicator. He said that a blocked air filter can also cause a MAF error. On the diagnosis the MAF showed a defect. The EGR was working OK perhaps a little low on high revs. Air filter was changed but left everything else - will check things one by one. Will let you know if and how things develop. Many thanks to you all for your assistance.
Nobby

 

[Nobby Clarke]

W210 E320 CDI engine switching to emergency run mode - final episode

Problem now fixed - it was a sticking EGR valve (thanks Dieselman - spot on). We took the vacuum actuated plunger cap off and found that the piston was sticking in the bore. We cleaned this out and put together again and the engine is running as smoothly as ever. Saved me Euro 400. Many thanks to everyone who responded.
Nobby Clarke

 

[kimjenkins]

Problem now fixed - it was a sticking EGR valve (thanks Dieselman - spot on). We took the vacuum actuated plunger cap off and found that the piston was sticking in the bore. We cleaned this out and put together again and the engine is running as smoothly as ever. Saved me Euro 400. Many thanks to everyone who responded.
Nobby Clarke

Where is the EGR valve on a 2002 E320 CDI Estate??

Thanks

 

[MERC'ED!]

Its on the right & just behind the rad looking into the engine bay, you will have to take off the engine cover I think, & its an alloy casing valves inside...

you can undo the hose that connects to it its like an elbow Big diameter!

Would love to help you furthur, BUT dont want to post links to other websites, forums etc...

Just Search the site, OR google it like I did...