R320 Issues
 

I'm having a heck of a time with my 2009 R320 with the Bluetec. It started after a fuel stop this weekend, when I was getting on the highway it went into a limp mode. I reset the codes but didn't write them down as I had my family with me.

We completed our trip in limp home mode. The car would alternate from a really loud turbo noise (like as loud as the AC fan on high) whooshing to no turbo noise at all. When I got home I pulled the codes again and had a 123900 The positive control deviation during boost pressure control is too high.

I thought I was looking for a boost leak with this so I pulled off the air charge pipe to the intercooler and found a bad o-ring. I replaced it and the turbo air inlet gasket which had also failed. I took the actuator linkage off and everything moved freely. I removed the cover of the actuator and ohm'd out all of the delicate connecting wires and all were ok. The actuator moves.

The car falls on its face at about 1200 RPM after reseting the code and goes into limp mode somewhere between 3000 and 4000 rpm. Sometimes this happens right away sometimes it doesn't. With my foot on the gas and other on the brake we can see the actuator move up and down trying to regulate the boost as the car bucks and surges.

Currently I am boosting upto about 24psi. On my scan tool I register idle at 13psi (even with the car turned off). I am also seeing similar numbers for exhaust backpressure. So I got the idea to run a DPF Regen on the car using my iCarsoft MBII. It didn't work. Now I have a 13AF00 Soot content of the Particulate Filter is too high. I did not have the error code until I ran the regen and it will not clear. The scanner lists the ash at 0g...so I don't know what's going on now.

I have tried a few other things but nothing really changes. Any help is appreciated. I need to understand what the control deviation is and why it is too high.

Wow, thanks for the details. Usually someone posts just a code number and says " tell me how to fix my car." It's also great you carry a scanner on the road.

I don't know these cars specifically but I'd be investigating if there is an improperly operating exhaust restricter flap. Some diesels do this to reduce emissions / lower warm up time. This might explain the " 13AF00 Soot content of the Particulate Filter is too high " , the " ash at 0g " is probably a time weighted calculation as I doubt there is a scale in the DPF.

I'd also be looking for the boost pressure sensor that is giving the 13 PSI reading. Hang a volt meter on the sensor and don't just rely on the scan tool readings. Sometimes when there is a fault, the ECM will substitute a value that ends up showing on the scanner.

Have a look on the ML, GL, G-Wagen, R-Class, Unimog, Sprinter forum.

The R320 has the same engine as the late 2000s MLs and E class (I have one of each!)

The DPF may well be clogged, and your forced regen was the last straw. The regen cycle forces the engine to run rich and dumps excess fuel down into the hot DPF, causing a process similar to what happens in a self cleaning oven.

There is a differential pressure sensor across the DPF under the vehicle that senses incoming and outgoing pressures and produces a signal to the ECU. This is what tells the ECU when to regen and when it is clogged.

There is a manifold pressure sensor downstream of the turbo but can’t remember where it is at the moment - maybe in the plastic box at the front left that joins the return from the intercooler to the two halves of the manifold.

The description of the problem ‘positive control deviation during boost pressure control too high’ means that the system is trying to command an increase in the boost pressure but it is overshooting the mark and going too high. If the turbo is actuating properly that is a good sign and I suspect the boost pressure sensor as well.

There is a Lubro Moly product meant for cleaning DPFs. Rollguy had a thread on that a while back and had good luck on an E class using it to clear out the DPF.

If you can get your hands on a Xentry computer it will help immensely. Not only will it show you the fault codes, it is hyperlinked to the repair/troubleshooting procedures.

Thank you for the responses. Do either of you know the values on the map/boost sensors? I'd like to eliminate those from the equasition.

Jay Bob, do you think that if the actuator is moving it is fine? I did notice when I removed the cover that there was a tad bit of play in the worm gear. Could it be possible that the overshooting is caused by the slop which is causing it to overshoot?

Ok I think I may have found the culprit....completely blocked air filters. I figured I'd pull the boxes (what a pita) and check them and they are plugged solid. I did a very short test drive with no boxes and the car pulled hard to redline with no new alarms.

My last post didn't work for some reason, but basically I pulled the airboxes off the R320 and the car ran perfect. I found that the air filters were plugged solid.

So I drove to the closest place to get an air filter for this pos (25 miles one way) got back wrestled the absolutely stupid air boxes back into the car and.....back to the same 123900 code. Thought perhaps it was something to do with running it with the map sensor outside of the air box so I removed it and tried again, same thing.

Earlier with the passenger airbox off it went into alarm straight away. When I pulled the drivers airbox I was able to push it hard multiple times without issues all the way to redline for about a mile w/o alarm. I'm starting to think there may be an issue with the MAF sensors or there's some type of massive blockage in the air duct on the drivers side?

Not sure why this forum is not letting me post, but in the event that this finally makes its way to anyone's eyes; I removed both air boxes again and can't make it out of the driveway without it going into alarm.

Is there any possibility that bad fuel could cause a 123900? Symptoms started about 1-2 miles after a fill up.

There is a forum rule that if you are a newbie then a moderator has to approve your first 5 posts. Just to keep the spammers out.

But yeah there is a strong correlation between your fueling and the trouble starting. I had a situation where the station near my house had the delivery driver stick the gas hose into the diesel underground tank filler. I got a fill of 1/2 gas 1/2 diesel and my OM642 hated it. Went to the dealer and they purged my fuel system.

Fuel station corporate agreed to pay for the repairs but then their liability carrier got involved and refused the claim. So as a result I refuse to ever trade at this particular oil company again. Let's just say they got their start in a big city in Dallas selling ice between two certain hours.

I pulled the generic code and it is a P0299 which indicates an underboost. So I went back and looked for a leak again, pulled the silencer off and blew into it (no leaks) pulled the intercooler outlet hose off and no visible cracks.*



The Turbo is way louder than normal when building boost sounds like a fan under the hood, I can find no leaks (even hit all the charge piping with soapy water). I assumed that it was loud due to the actuator opening the wastegate while attempting to regulate the boost. There's no noise at idle or without a load on the engine. I did find an extremely small air leak around the intake manifold, the water bubbled but did not change bubble rate*when boost was built.*



At this point I can only figure out that either: 1) I have a leak that I can't find, possibly the passenger's intake or somewhere on the turbo itself (there is no play or drag*on*the turbo), 2) The actuator isn't functioning correctly it's going full open on the wastegate or perhaps it just isn't regulating correctly, 3) One of the MAF or MAP sensors is bad and throwing the readings off so the turbo actuator is going crazy trying to compensate.*

I have driven the vehicle approx. 170miles in limp home mode so hopefully it is not gas in the diesel...yikes. How did you figure out that gas was in the diesel?

I actually had fueled the ML320, the E300, and the 300TD all on the same day. They all started running weird. The IDIs hated it more than the CDI engine. The IDIs would not restart when hot. Pulled off the fuel cap and got a big whiff of gasoline.

Another test is putting the liquid in a styrofoam cup. A gas mix will dissolve the cup pretty rapidly where straight diesel won't.

I did this when the guys at old work put diesel in a gas man lift. ( The rental co told the guys it was a diesel lift. )

First if it started very shortly after a refueling. Get the fuel removed and replaced. It may not be bad but you cannot chance it.

Describe the type of place you fueled at. Some places are still supplied by contracted bulk carriers. They might not bother to clean out a previous load of whatever they had on board before filling with diesel.

It is not always gas contamination you are dealing with. One of the primary reasons I do not want the most modern diesels. A load of bad fuel can cost you a bundle to address. I am driving a less sophisticated non Mercedes diesel right now. Large truck stops represent the safest filling places. I also use a higher volume local place. I know they are serviced by dedicated tankers. I still got a lot of water one time in the middle of winter there.

Finally had time to make some headway here and some head way I believe I have made. I built a smoke "machine" to try and find the boost leak. I used a candle that was done for and put some paper towels into it, drilled 2 7/6" holes in the wooden top. I used some really old fuel line left over from a 1985 Grand Wagoneer and a sandblasting tube that has never been used. I zip tied a sandwich baggy to the turbo and to the blasting tube and applied air pressure. Here's my super sketchy smoke apparatus.

https://thumbnails-photos.amazon.com...A10984NNBN4RJK

After a while I noticed a lot of smoke coming out of the passenger side. At first I was worried it was a head gasket. I removed the aircleaner assembly (what a pain in the bottom). I eventually saw it coming out of a hole in the back of the throttle body flange.

https://thumbnails-photos.amazon.com...A10984NNBN4RJK

https://thumbnails-photos.amazon.com...A10984NNBN4RJK

After spending some time on the phone with the dealer we were able to determine that a sensor was supposed to be in that hole. It took some sleuthing to find the little bugger as it had wrapped around and behind some other wiring. Seems that the clip had broken off the sensor and it ejected out of the flange.

The sensor is an air restriction sensor. Here's the broken one:

https://thumbnails-photos.amazon.com...A10984NNBN4RJK

I'm picking up the new sensor this weekend and hope to have this resolved Sunday.

Yes it is easy to miss that sensor.

There are 3 electrical devices in the mixing chamber. The temperature sensor that plugs in the hole, the flap motor, and the pressure sensor. Plus the battery feed and glow plug/LIN bus connector for the glow plug relay riding on top of the mixer.

I just went through this on my 2008 E320. The alternator went out at 195 k miles. In order to replace the alt you have to remove all the intake tract on the front of the engine. All the way from the turbo outlet pipe, through the muffler on the right, the intercooler hoses, and the mixing chamber and resonance pod.

WIS tells you to replace all these o-rings and gaskets. I think the previous mechanic that did the oil cooler seals did not do this, as the gaskets were not on the repair bill of materials. I had massive crap leakage out several of the joints, including one right over the alternator. The alternator was totally caked in black goo. I brought a pair of nitrile gloves for the poor guy at NAPA who had to pack it up for the core.

I was also getting a whistling noise at boost which was a dead giveaway for an intake tract leak.

Renewed all the seals (about $50 or so) and cleaned up all the black crap, and replaced the alternator and serpentine belt, much better (and quieter when you punch it) now.

Also a totally “while you’re in there” thing: replace the camshaft position sensor. This sensor is vital for the engine to operate. If it dies it will leave you stranded. $100 at the dealer, cheap insurance. It can be replaced without having to run adaptations (unlike the crank sensor, that has to be matched to the injectors with Xentry).