Sounds like one of the pipes from the turbo compressor outlet came loose. Happened to me on a trip to Eastern Canada. We were just going over the Cascades here in Washington eastbound, tried to pass a truck and "pop" heard a noise and then a serious lack of power! Very hard to pass that truck them!! There were no engine error lights [as I recall].
The charge air pipe to the intercooler had come loose when a bolt holding the bracket broke (the bolt - holds the bracket AND the engine cover ball/socket ball - had been removed and replaced by the dealer earlier when replacing the M55 servomotor). Dealer in Kennewick couldn't get the broken piece of bolt out of the aluminum intake manifold. Managed to limp back home and get the car to the original dealer to fix his error!!! Trip cancelled for the summer!!!!
Check carefully all the connections from the turbo to the charge air cooler and from the cooler to the intake manifolds. Also look for leaks in the charge air cooler. If you lost that much power the leak is a major one and it will not be a small hole!

 

Thanks 4D, I have owned a few turbo'd cars, but this is my first time that the turbo failed to respond but the engine works normally - just like a non turbo would.

Usually, when the intercooler hose comes loose/fails, the engine doesn't want to go over idle speed. The ECM checks throttle position and adds fuel, the maf measures air intake, and the boost pressure sensor is still at zero, and the engine just boggs down.

I will have a look under the dumb plastic engine cover tomorrow. I wonder why all of the manufactures decided to put a plastic thing over the engine? Are they afraid of something?

 

No changes. The temps are finally above freezing, I had thought that perhaps the intercooler froze up enough to block large amounts of air but it doesn't appear that is the case.

The IC piping is all tight, no obvious leaks.

I do not know where the boost controller is. My other cars all had vacuum controlled BCSs, easy to find.

The dealer suggested to come in next week. Let's hope it is something simple like a wastegate stuck open.

 

Resolved, somewhat

So, I let the engine warm up in the garage and took it for a short spin. The boost kicked in on demand!

Now, I have to assume that there was water in the fuel filter and it froze, blocking some of the fuel. Or some strange electrical problem that prevents kickdown and turbo engagement when cold. Today is the first day above freezing this month. The fuel gauge is just shy of full.


I will find out on Monday when the high is supposed to remain below 0F.

 

Well, it just won't work when cold. I parked at the airport for a week, -25F when I left and 30F when I got back to the car. After scraping the ice off the windows, I noticed that the yellow check engine light was on. I drove home without boost and the tranny upshifting at around 1800 rpm. It took about 60 seconds to get to 60-65mph but cruised nicely.

This might be limp home mode???

The error code from a generic scanner showed P1402 - EGR position invalid.

I found the same problem with the ML320 people on this forum, some suggested cleaning the EGR valve while others found that didn't help. A MB scanner will be needed to get the correct code in detail.

The car only has 70K miles. Our winter diesel is very well treated for super cold temps, almost too much as it will pre detonate under load (when the turbo is working).

 

Sludge/carbon/soot build up, clean it up, likely the intake is really clogged too. It might be too late to save the egr valve, sometimes they cannot be saved. Limp mode can be triggered from overboost, egr issues, temp issues, lots of things but there will be a fault stored from the event saved in the ecm, a generic scan tool will not always find these codes. It is always best to have a star scan when it is happening to track it down.

 

http://www.benzworld.org/forums/w164-m-class/1553151-p1402-slow-acceleration-2007-ml-320-a.html

welcome to the club

 

This problem only happens when the car temps fall below 32F. Letting the engine warm up a bit, stopping and restarting the car will give you normal accelleration. The problem seems to be with the differential pressure sensor:
2008 Mercedes-Benz GL320 Parts - Mercedes Parts Center - Call (800) 587-4863 for Genuine Mercedes Parts and Accessories
The yellow 'check engine' light produces a P1402 generic code. This points you to the EGR valve, but that is WRONG. While the EGR valve may be coated in soot, it is in fact still working and impervious to cold temps.

BTW, my original battery is no longer storing energy after only 5 years and it is time to get a new AGM battery. Of course, a garage temp of 25F doesn't help either.

 

Is this the same sensor?
ATTACHMENT PARTS,HEATER PLUGS,AND SPEED SENDER UNIT. Fits: Mercedes | Mercedes-Benz of South Atlanta

 

We're both dealing with the same issue at the same time! I know we're criss-crossing a few threads now. I tried EGR cleaning and differential pressure sensor. It seems for most the diff pressure sensor was the culprit. For me...no. My next try is a cheap $18 try...air/charge pressure sensor. I'll let you know how it goes!

I had an 08 ML320 CDI from new up to 85k miles and never had a problem like this whatsoever. I had originally chalked it up to cold weather (it's nasty this year). I hope your fix comes fast!

 

I just changed that pressure sensor, based on that exact diagram. I'm waiting for part #100, as well, since the pressure sensor did not resolve my issues. I was having difficulty locating right part b/c of naming. After looking at many different reputable parts sources, I realized they were the same part and ordered from my preferred vendor (RMeuropean, autohausaz or rock auto). From what I see, the diff pressure sensor on some sites is called the MAP sensor or just pressure sensor. The charge sensor has also been called the air intake/charge pressure sensor, etc. Semantics are killing me. The diagrams showing the part and location on mbpartsworld have been super helpful.

Good luck!

 

There are 2 mercedes part numbers; the old part number is 0061539528, the new part is 6429050100.

I talked to a non-Mercedes mechanic who specializes in older MB cars. He said the intake manifolds get very dirty and can plug up the airflow. Nice to know, but the cost of removing and cleaning is probably too much for my bank account.

 

I'm hoping, like all of us, that it may just be sensor related. My EGR valve was not nearly as bad as pics/videos I've seen in posts. It was actually dirty, but cleaned up to near OEM sheen. Since I had fumbled on the hose clamp reconnects and had a small leak, I had to pop her off after driving her post EGR clean. It popped right out and was the same as when I had reinstalled her...clean.

 

Replaced DPF pressure sensor and it fixed it. Just for the future refference:
Part number that was on the old sensor that I've removed: A 006 153 49 28
"New" part number that was shipped to me: A 642 905 01 00

 

Battery died

This is so interesting! My battery was slowly nearing its demise this winter. I was too absorbed in correcting the non-turbo error and EGR error to look at other alternatives.

I solved the problem without any engine work! I replaced the battery.

So interesting... but it made complete sense. The computers did not have enough voltage to complete their boot up process and that triggered the error. That it only happened when it was below freezing is a direct result of how a cold battery works.

So, replace your 5 year old battery!

 

This is so interesting! My battery was slowly nearing its demise this winter. I was too absorbed in correcting the non-turbo error and EGR error to look at other alternatives.

I solved the problem without any engine work! I replaced the battery.

So interesting... but it made complete sense. The computers did not have enough voltage to complete their boot up process and that triggered the error. That it only happened when it was below freezing is a direct result of how a cold battery works.

So, replace your 5 year old battery!

I tackled my battery as part of my troubleshooting. I had it tested and the battery was in "limp mode" too! I figured for a 5-6 year old battery...it was time for a AGM! Glad a new battery fixed your issues.

 

for my 2008 ml320 cdi, last year I replaced the DPF sensor and everything was ok by after,
I live in montreal, last few days was -25 deg, the same problem is coming
tomorrow it will be -2, we will see if it s working good

 

wow that is cold

please post back and let us know if yours has anymore problems

 

I told you guys, today it s -2, everything working good
I will change this sensor, very easy, one screw and two hoses, sensor in montreal cost about 75$

 

that is great

this is an easy and cheap fix