bd041556

My wife has a 2006 E320 CDI that she has driven since new. It now has 156,000 miles on it. It has been a very reliable car and she likes it a lot, but lately it has been acting up, and I am hoping someone on the forum will recognize the symptoms so we can get it properly fixed.

It all started when she got in an accident with it. She bashed in the front at a slow enough speed that the air bags didn’t go off, but fast enough to require about $10,000 in repairs. With 156,000 miles, I thought the insurance company would have totaled it out, but they didn’t, and we have had problems with it since getting it back from the body shop. It’s only been driven about 300 miles since the accident.

It now frequently goes into a mode where it produces very little power. As those of you with 320 CDI’s know, the car normally has plenty of power, but when it goes into this low-power mode, it will not exceed 3000 RPM, the transmission will not kick down properly, and if left to its own devices it’s hard to get it over about 50 mph. You have to manually shift it to get it going, and even then it feels very sluggish.

We took it to the dealer (who has maintained it since new), and they replaced the EGR valve, updated the CDI control unit, and replaced the actuator motor for the intake shutoff. They also replaced the thermostat (which must have been damaged in the accident, since before replacing it, the water temperature wouldn’t get above 60 degrees), charging me a total of $2100. That made no difference, except that now it turns on the “check engine” light which it did not do before.

When my wife took it back to the dealer to get them to try again, they reported the following:

“We found excessive carbon buildup throughout entire engine causing intake manifold flaps to bind and not fully open and therefore there is not enough air travelling to the cylinders to fire. In addition to that the EGR system is also clogged with carbon causing exhaust fumes to build back pressure to motor”.

And suggested that we give up on the car. They didn't tell me what code was causing the check engine light, and I am too irritated with them to communicate further with them.

I think the dealer simply doesn’t know what is wrong and is hoping we’ll just buy a new car, accepting their low-ball trade-in value. Here are some observations:

1. When it goes into low-power mode, if you turn the car off and turn it back on, it runs with normal power for a while.

2. When it is in the low power mode, even if you put it in neutral and push the accelerator, the engine will not exceed 3000 RPM. When it is running normally, it shoots up above 4000 RPM quickly and easily.

3. If you drive the car aggressively it doesn’t go into the low-power mode. I took it out on a local highway for an “Italian tune-up” and drove it in third gear at about 80 mph for 20 miles or so and there was no sign of problems until I got off the highway and drove on surface streets for a while. Then it went into limp mode until I turned if off and on again, whereupon it ran fine (driving normally) for 10 minutes or so before again going into limp mode.

4. When it came back from the body shop, the alternator wasn’t working correctly even after replacing it with a new one. The dealer was able to diagnose this as a pinched wire in the wiring harness, and they did fix it (which I was impressed with).

If the dealer’s diagnosis was right, the car would run poorly all the time, rather than going into and out of the low-power mode. It acts like there is some sort of sensor that is intermittently giving wrong information to the engine control unit, causing it to limit fuel or turbocharge boost or something. The fact that there was accident damage to the wiring harness to the alternator might mean that there was other damage as well. It seems nearly certain to me that the problem was caused by the accident somehow.

The diesel models are pretty rare around here, so I don't know of any shop that specializes in them. I'm going to take it to an independent shop that specializes in German cars in general and works on some Volkswagen CDI's, hopefully they'll be able to fix it. But if you have any educated guesses as to what could cause the symptoms described, please feel free to share them.

Thanks in advance for any suggestions or advice.

Barry

nizam9w2ms

Hi Barry,

I have similar problem to my E270 CDI before.
I believe since day one you never change Catalytic Converters or Oxygen Sensor.
Please ask your mechanic to check or replace this two items.

Cheers.

rcheatum

I know when fuel filter gets clogged sometimes they run but cannot go above 50 miles per hour since no fuel is passing thru the dirty filter for the added acceleration.

Dan Wang

I would check out the EGR. It is quite simple to remove it and spray some cleaner to remove the carbon build up. Or just replace it with a new one.

What you are experiencing is something is triggering the car to go into "limp mode". Have another dealer hookup the the car to a SDS machines and it should tell you what is throught the fault code.

bd041556

I'll get them to check the oxygen sensor.

If it was a dirty fuel filter, I think it would run poorly all the time, rather than intermittently.

They did replace the EGR valve, I think they are saying that the plumbing to it is also clogged with carbon. But I think that would also make it run poorly all the time rather than intermittently.

Thanks for the suggestions!

Barry

mrhoef

I have the E320 with the straight 6 cylinder and having the same problem. it goes in a limp mode which disables the kickdown and rpm will not go over 3000 rpm. A simple restart of the engine solves the problem for quite a while.
I haven't found an y reason for it yet and it is a shame you didn't get more response on your thread.
I have found on epossible explanation which is about the intake motor; it seems to drown in oil leak of the turbo because of a badly constructed seal. I am not sure if your V-6 has the same inake motor though

Let me know if you ever found the cause of your problems

bd041556

Mine has the straight six also. The dealer had replaced the intake motor that you are describing (I think it is called a "setting motor"), which opens vanes in the intake manifold. That did no good in my case. I took it to an independent mechanic, who thought that the replacement motor might be defective, so he tried replacing it again, with no improvement. He then concluded that the vanes inside the intake manifold were sticking. There is apparently no way to clean them, the only cure is to replace the intake manifold. He did that and it fixed the problem. The bill came to $2600 - about $1200 for the parts and the rest labor, if I remember correctly.

I did not believe it could be something mechanical like this, because cycling the ignition off and on cause the problem to temporarily disappear. But there you have it.

Barry

delviacv2

Since the car was in a accident check all the turbo piping including the intercooler for leaks, when I bough my car I had the same problem and it turn out to be a leak in the intercooler, it used to do exactly what yours is doing.

Delvi.

Tschuss_Bill

If it is EGR related, you might try the EGR delete which will disable the EGR circuit from funtioning, but tell the ECU that the EGR is still functioning. I'd find an independent to check both intake and EGR for excess carbon build up. Carbon build up (coking) can often be cleaned as opposed to requiring new parts.

This coking is caused by re-circulation of sooty exhaust gases along with oily crankcase vapors into the intake manifold. Lots written out there on the topic regarding causes. Lots of myth too.

Good luck, be sure to post how it is eventually resolved.

-Bill

2slowcdi

This sounds like a Mass Air Flow sensor ,but that would make the Check Engine come on.
I replaced mine just a few months ago and it would do the same thing. My CEL did come on.

I would never had guessed the intake vanes.
Glad you got it fixed.

Jack Dash

I had a similar problem with my 2000 220 CDI & several garages suggested all the above without success. I found out eventually that my problem was a blocked oil filter in the gearbox & by replacing it and re-filling with fresh oil it solved the problem for me.
I hope this helps

brenner

I had the same problem. The intake manifold CAN be cleaned. I did it. It took me about 4 hours to remove and clean it. After the repair, my car ran like new and it quit blowing black smoke when accelerating. This problem is well known in Germany and UK. Did the MB dealer give back some of the wasted money?

edwinwalke

Barry, I have a 06 E320 CDI that was doing the exact same thing that you describe that yours is doing. Took it to the dealer and they could not get it to go into limp mode. Recommended Fuel filter change. I tried the fuel filter and that did not solve the problem. I got and idea from a thread on one of the forums and disconnected the EGR valve. Problem went away. I have been driving it now for close to 10K miles with no problems. You might want to try this and if it eliminates the problem go back to your dealer that replaced the EGR valve and ask them to do a little more analysis -- mine works just fine with the EGR disabled.

65aircooled

The above post from the OP, he had the problem solved and describes the fix six posts above

Tschuss_Bill

I know of a method for loosening up carboned or coked up vnt mechanism on the turbo. From the VW TDI world it is using easy off oven cleaner. On the TDI there was an elbow joint on the EGR cooler that when removed, provided easy off access to the VNT mechanism. Did an oil change thereafter and it ran like a bat out of hell. That was 50k miles ago. The plumbing is different on the CDI, I would figure out a way to try this before I'd spend 2k or 3k.

Niraj

Same issue described by Barry. My car has only done 35,500 miles and in immaculate condition. No accidents etc. Day before yesterday went into limp mode - can not go beyond 20 mph and took it straight to garage. Mechanic said there is error on EGR Valve but that valve was showing clean, however, we replaced it but still engine can not rave up. It did not come out of limp mode. The intake manifolder has lots of carbon deposited on it. Also catalyst converter filters are blocked. Car never shown any engine sign on dashboard. It seems this is some manufacturing defect which is causing this carbon build up even at 35,500 miles. Any idea what needs done here ? My worry is could have this carbon gone inside engine ? Car system is not designed properly to give proper error messages on dash board and it never shows engine symbol the way it is mentioned in their manuals. I think this is nightmare and most weird thing you can expect in such high level top market classic cars. Limp mode feels similar to sudden heart-attack of this car and no proper error codes in diagnostics except EGR Valve - well it is upstream to that with intake manifolder etc..

kajtek1

Cats blocked and you worry about EGR?
Or is it particle filter on your car?
I heard that they can get build up if you constantly drive them cold, meaning driving like grandma.
What year is the E220 ?

Niraj

The reg is year 2006. E220 CDI Avantgard. Will catalysts cleaning sort the issue ?

Niraj

Also mechanic tried raving up the engine without catalyst converter. i.e. after removing catalyst converter and still it will not come out of limp mode. Do you think this is still catalyst converter issue ? I believe that this is Mercedes design issue which never shows the right alerts on dash board. You can not expect such basic huge flaws in this sort of top of the range cars.

kajtek1

Even if you remove the problem, the car will be in limp mode at least for some time.
You need to find a mechanic who knows how to erase the codes.
That and also the fact that computer will not allow high rpm without a load.

mrhoef

Most likely the car goes into limp mode as a result of the carbon build up. Several possible reasons: actuator motor of the vanes in the intake manifold cannot run, because vanes are jammed. Same for the EGR actuator; if it cannot move it goes in limp mode.
You must find the reason for the carbon build up. If the turbo is leaking oil on the seal you will have a very greasy build up in the manifold and EGR. If the engine vent, which returns air from the oilpan into the intake you will find more carbon, because the vent contains hot exhaust gas because of leaking piston rings.
If the O2 sensors are not working properly the car will most likely smoke badly if accelerating; same when the intercooler or intercooler pipes are leaking. Basically, if it runs rich, it will smoke black from the exhaust.
Only way to go is; clean up manifold and egr (big job) and then find the reason for the carbon/oil build up.
All together a big job and not something you can have the stealer do. Either a good indie or get the spanners out for a few days.
Good luck

Niraj

Thanks a lot for your ideas. Yes, actually it was an actuator problem with Turbo. My mechanic did some repair and got sorted without replacing the whole of Turbo (actuator is part of Turbo). Also the front small auxiliary battery was replaced as it was not doing well and hence the battery sign on dash board and the entire job done. It came out nice from limp mode. Got full serviced so now they changed all the filters (air, fuel, oil), engine and other oils, also replaced break pads and break sensors. All in all £470. Can't ask for better. Now only thing is in automatic gears in C/S Mode. It runs like a charm in S mode than it does on C. In C it goes upto 300 rpm to change gear whereas in S it changes at 200 rpm up to 3 gear and then on 250 rpm for 4th and 5th. I keep it S - hopefully it is OK. Many thanks, Neeraj

ptkacik

My '05 CDI had the limp home thing years ago due to an EGR problem and has been good ever since.

When the manifold plugs up with carbon, what is the fault? Does the OBDII port say something specific or maybe the speedometer??? I guess I'm due for this failure since I'm at 160,000 miles.

Peter