You checked the most common cause, but you also need to check the waste gate. If it sticks open that will underboost as well. Do NOT oil it with improper stuff unless you like setting your vehicle on fire.
First real problem @ 79k miles
Van lost power on freeway and threw a turbo underboost P0299 code. I believe it went into limp mode at that time. Anyways i ended up pulling the charge air hoses off the intercooler and throttle body to inspect for cracks. They all look good to me and the rubber o-rings still intact. At that time i noticed MAF sensor was filthy so i cleaned that and cleared the code and went for a 4 mile drive and then another. So far So good. But...............anyways, anybody else have any turbo issues besides me?
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Yeah, i saw the waste gate valve. I didn't mess with it as it's hidden under a heat shield. Is the valve serviceable without removing turbo and what type of waste gate is it? Vanes or just a flapper?You checked the most common cause, but you also need to check the waste gate. If it sticks open that will underboost as well. Do NOT oil it with improper stuff unless you like setting your vehicle on fire.
Honestly not sure as I’m new to the vehicle, but if it’s got an actuator it’s a flapper. Very few gas VNTs out there, and they are all electrically controlled.
I would normally say check the MAP sensor and it’s wiring, except the van likely wouldn’t run without that working well.
Otherwise it may have been an early warning of a turbo going out if this was underboost during a throttle transient (acceleration). If the turbo is lagging that is an early indication of it going out, though normally a fairly small sign. I’m not sure how sensitive these engine are.
Otherwise it may have been an early warning of a turbo going out if this was underboost during a throttle transient (acceleration). If the turbo is lagging that is an early indication of it going out, though normally a fairly small sign. I’m not sure how sensitive these engine are.
After another P0299 code thrown. I decided to do some troubleshooting. Turned out to be the vacuum actuator leaking by and never fully seating the waste-gate. A quick pull with a mighty vac handheld vacuum pump identified the problem. Of course Mercedes doesn't sell the actuator separately AFAIK. But, i was able to obtain one from China off ebay after a long wait. (first shipment lost). Anyways, If it doesn't hold up i'll get one from Mamba.I would normally say check the MAP sensor and it’s wiring, except the van likely wouldn’t run without that working well.
Otherwise it may have been an early warning of a turbo going out if this was underboost during a throttle transient (acceleration). If the turbo is lagging that is an early indication of it going out, though normally a fairly small sign. I’m not sure how sensitive these engine are.
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Great fix kbcool! The stealership would probably hose you and say the entire unit including turbo has to be replaced....and we found a small crack on the exhaust manifold, so that's a another $3000. Lol.
That's great the arm is the same lenth.
That's great the arm is the same lenth.
did the new wastegate solve your problem? My Metris started to develop similar symptoms and threw a code. Initial inspection of the piping looks good so I am trying to diagnose the cause of the under boost.After another P0299 code thrown. I decided to do some troubleshooting. Turned out to be the vacuum actuator leaking by and never fully seating the waste-gate. A quick pull with a mighty vac handheld vacuum pump identified the problem. Of course Mercedes doesn't sell the actuator separately AFAIK. But, i was able to obtain one from China off ebay after a long wait. (first shipment lost). Anyways, If it doesn't hold up i'll get one from Mamba.
Yes, it solved the problem. To diagnose without guessing, you need to connect a handheld vacuum tester to the actuator diaphragm and see if it moves the wastegate arm fully and holds it without leaking. Mine would just barely move as i pumped it and immediately leaked out. It felt like i was putting air into a tire with a big hole in it. Heres a link to the tester i bought. Amazon.com: Mityvac MV8510 Silverline Elite Hand Pump : Automotivedid the new wastegate solve your problem? My Metris started to develop similar symptoms and threw a code. Initial inspection of the piping looks good so I am trying to diagnose the cause of the under boost.
Just want to chime and thank kbcool for posting this. I had similar symptoms at 109k, proceeded by increasingly bad fuel economy (like 15 mpg) before it finally started limping and throwing codes. Was able to find the wastegate actuator on eBay from a domestic source, and am big time relieved it wasn’t the whole turbo!
Oh lovely. My van just MILed and went into limp mode ; restart solved limp mode and it hasn’t gone back. Bought a Launch 319 and it is P0299. I don’t want to replace a whole turbo, which I assume is what the dealer does. Any place advised for getting instructions on how to do this?
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@kbcool provided the link and can probably tell you how if this is your issue.
I got that far; given the commonness of the problem, and the $27 I paid for the part, I’m going on the assumption that’s it. I was more interested in what’s involved in changing it.
The actuators held on by 2 nuts. I used a small gear wrench for removal. I first removed the air cleaner assembly then the heat shield covering the turbo. You may also have to remove the engine sound cover to access the torx bolts holding the heat shield on. I did not as mine was already removed when i did the spark plugs and i never bothered to put it back on. But, other than that it's pretty easy. If you could slip the c-clip off the waste gate from underneath the vehicle safely and squeeze a gear wrench on the 2 nuts. You may not have to remove anything other than the bad part. Let us know how it goes.I got that far; given the commonness of the problem, and the $27 I paid for the part, I’m going on the assumption that’s it. I was more interested in what’s involved in changing it.
I will. This is just the first real wrenching I’ve done on the thing besides the time where I opened it to add washer fluid and ended up tearing some pop rivets off to reseat the hood latch sensor which put me off of opening the hood, so I’m nervous; should I get a service manual to guide me on removing the intake/heatsheild/noise cover or are they pretty straight forward? If the dealer replaced the actuator rather than the $4k assembly I wouldn’t be trying this 😞The actuators held on by 2 nuts. I used a small gear wrench for removal. I first removed the air cleaner assembly then the heat shield covering the turbo. You may also have to remove the engine sound cover to access the torx bolts holding the heat shield on. I did not as mine was already removed when i did the spark plugs and i never bothered to put it back on. But, other than that it's pretty easy. If you could slip the c-clip off the waste gate from underneath the vehicle safely and squeeze a gear wrench on the 2 nuts. You may not have to remove anything other than the bad part. Let us know how it goes.
Another question: after the first event where it went into limp mode it hasn’t gone back into it since, and I reset the DTC with the scanner yesterday and the MIL has stayed off so far today. Should I wait until it does it again, or replace it as soon as I have a few spare hours once the part arrives?
To know for sure. You need to perform a leak down test on the actuator using a hand held vacuum pump. As far as the sound cover removal. Take off the 2 air cleaner brackets under the cowl. Also, be careful around the radiator bottle quick connect fitting's. They tend to snap off easily with just a bump.I will. This is just the first real wrenching I’ve done on the thing besides the time where I opened it to add washer fluid and ended up tearing some pop rivets off to reseat the hood latch sensor which put me off of opening the hood, so I’m nervous; should I get a service manual to guide me on removing the intake/heatsheild/noise cover or are they pretty straight forward? If the dealer replaced the actuator rather than the $4k assembly I wouldn’t be trying this 😞
Another question: after the first event where it went into limp mode it hasn’t gone back into it since, and I reset the DTC with the scanner yesterday and the MIL has stayed off so far today. Should I wait until it does it again, or replace it as soon as I have a few spare hours once the part arrives?
It very well could be a bad hose.
could you list your year and mileage?
Mine? 2016, close to 174k.
This is definitely above my head; I can’t even figure out how to get the noise cover off let alone the heat shield. Does anyone know a repair shop in the Philly area that would tackle this kind of job without replacing the turbo?To know for sure. You need to perform a leak down test on the actuator using a hand held vacuum pump. As far as the sound cover removal. Take off the 2 air cleaner brackets under the cowl. Also, be careful around the radiator bottle quick connect fitting's. They tend to snap off easily with just a bump.
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