Low boost/slow response fix for C43 C450 and the C400. Vacuum pump valve fix for M276

If you've been having slow 0-60 times, slow boost response and/or your entire first gear feels slow when you're brake boosting your launch... then you might want to check the vacuum pump diaphragm/check valve for the wastegate solenoid.
This is a short video on removing it, and comparing it to one I got on ebay for $9.99 which was advertised for Ford Ecoboost vehicles. So it was cheaper, but the same as the one advertised for Mercedes on ebay.
I've already replaced mine last year and fixed the issue I was having, however...
If your diaphragm is not like in the video, if it's disintegrated or missing then you need to replace it. It's the orange rubber piece inside the connector shown.
The C63/E63 use the same vacuum pump, and I recently saw that they too suffer from this issue. Check your valve!

[@arlokkkk]

thanks. Good to know.

[@guillermolrd]

Muchísimas gracias,me llega en 20 días,a ver qué tal se porta luego el coche,ahora me hacía en 5segundos el 0/100…

[@chrisc8089]

You're welcome, keep us updated on how it turns out!

[@tomekkorczak377]

My launch control looks similary . First gear almost zero boost going like 200hp and suddenly 2nd gear kick in the back . Do you think i have same issue ?

[@chrisc8089]

Sounds like the same problem, only one way to find out! Check this valve inside the connector, and luckily it's cheap and quick to replace. It's a good start to diagnosing your issue, which I'm guessing is the same problem

[@tabikes69]

Where did you get the cool intake??

[@chrisc8089]

This is the LEM air intakes, which I then wrapped in gold reflective heat wrap. They also have a new version of an intake releasing soon, which upgrades the inlet of the OEM intakes. Both are solid options

[@snipz3214]

My 0-60 times are the same as what you described. They’re as fast as stock. But my 100-200km/hr are faster than stock. First gear doesn’t pull hard at all. You think it’s this?

[@chrisc8089]

Sounds identical to the issues I had, but it could be a number of things. Luckily, It's fairly quick to pull the connector out and check for the orange valve, and if it's missing pieces or missing altogether. I think checking this valve should be the first thing anyone should check when having these symptoms.

[@greyeuro]

Did you order from a US vendor? Would you happen to have the link of the exact one you purchased from? My C450 sometimes stumbles upon 1st gear launch then recovers.

[@chrisc8089]

The one I purchased was shipped out of China This is the one I bought from my video, that I compared to OEM valve: www.ebay.com/itm/234551686530?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=1bPiXzwbTRC&sssrc=2349624&ssuid=zhNR6hqWTti&var=&widget_ver=artemis&media=COPY You can find this one from a US reseller, searching for the same Ford ecoboost valve.

[@greyeuro]

@@chrisc8089 thanks man. i ended up finding one on amazon. they mentioned it from ukraine & good quality lol. Cant wait to try it on my tuned c450

[@chrisc8089]

@@greyeuro yw! It definitely made a big difference for me and many others who had this problem

[@greyeuro]

@@chrisc8089 Just did this to mine. I had to wait about a month for the part to arrive from Ukraine but well worth it. Ran an 11.46 dragy run before on my c450. Now the car feels faster. Thanks again for video!

[@chrisc8089]

@greyeuro nice, you're welcome bro! I saw your Dragy video on the FB group. That's a solid run! Good stuff

[@adamchambers3438]

Is there just that one? MY C450 isn't making its commanded boost and I took the one out that you show and the orange rubber stopper thing is coming out and not a complete disk anymore. Ordered a new one and hoping it fixes my problem!

[@chrisc8089]

Yes, this is the only valve for the pump. The other end of the hose connected to the vacuum pump is connected to the "pressure transducer," aka the wastegate solenoid valve. If fixing this vacuum pump valve doesn't completely resolve your problem, it may possibly be that solenoid isn't operating correctly anymore. Or something else completely such as a boost leak etc. When I first discovered my vacuum pump valve was damaged, it also was not a complete disc anymore. It was disintegrated to about less than half the original size

[@adamchambers3438]

@@chrisc8089 Awesome man, I definitely appreciate you. This is the only information I have seen online regarding this. My valve will be here tomorrow and I will run some more logs.

[@jevaughnlewis9774]

Hey bro, do you have any idea why my boost gauge doesn’t work? I have a 16 c450

[@chrisc8089]

Yes, you're referring to the boost gauge of the AMG menu? If so, from what I guess the boost data isn't being transmitted to or used by the C450 gauge cluster. You'd think this could be fixed with proper programming but it seems that either it's not possible or that nobody has done it. Perhaps it's too much work to make happen from a programming perspective. People are activating the menu on the C450 which doesn't come with it from the factory, and the boost reference gauge just doesn't work. I had mine activated a couple years ago and the boost gauge doesn't even appear on the menu, only the oil temps. So in some cars where boost gauge option isn't working some of the guys selling activations are leaving that out instead of enabling it. I've heard a couple of times people saying that the gauge clusters are very slightly different after 2016 for the C43, and that there's one extra wire in the harness. They seem to indicate that's the reason why but I've not seen any proof to that, and to me it's all hearsay until someone actually proves it.

[@Boosted.450]

What do you look at to see if it needs to be replaced the orange thing, or the first rubber pump you unplugged from it?

[@chrisc8089]

The orange piece, which is the flexible diaphragm/valve that breaks down over time. It should be completely whole and no part of it missing (as in the video). Also the o-ring on the connector I removed should be intact and not torn. The hose should also be in good condition too, so that there is no vacuum leak. There's most likely nothing wrong with the hose but always good to take a quick look.

[@Boosted.450]

@@chrisc8089 thank you because i notice after a couple hard launches the car feels like it has no boost. And the exhaust becomes REALLY loud at low rpms when there’s no boost.

[@chrisc8089]

@Boosted.450 although you should check this vacuum pump valve since they don't seem to last long... it definitely sounds like you have a different problem if the exhaust became louder. Without hearing or seeing the car, I'd guess possibly an exhaust leak, boost leak or something else ( hopefully not worse). From what I've seen other people mention, a common area for boost leak is the connection from the top of the intercooler to intake manifold.

[@Boosted.450]

@@chrisc8089 thanks i’ll give it a look

[@Phillipsonfire123]

Will this cause a no boost situation as well ?

[@chrisc8089]

No some boost can still be built up even if the diaphragm valve was completely missing. If you are experiencing no boost do you also have an error code/CEL thrown by the ECU?

[@dhillon21]

I have a 2015 c400 stage 1 Eurocharged tuned w stock intakes. Car pulls HARD when it has boost but when i try launching it, i think the wastegate opens and it dumps all the boost. My car goes up to high rpm’s and it still has no boost. Turning the car off and back on would usually bring back the boost but this would make it so i cannot launch the car. NOW, my car is making NO boost at all. the exhaust sounds louder (I have a cutout in place of the second resonator from the front). Sometimes, driving the car for a while helps bring back some boost but it hasn’t fully came back in the last few days. Could this be the issue? or would it be something different?

[@chrisc8089]

At first what you described sounds just like the same problem my car had. But I'm unsure what you mean about it would make it so that you cannot launch the car again. However, the second half of what you mentioned sounds like a different issue altogether. It could be several things causing that, but I would've thought that the car would be throwing a code in that situation. If the diverter valves were commanded open it would dump any boost the car would be trying to make, and your car would feel like it's only making about 200 hp. The car can do other things to prevent boost from building, such as limiting throttle to around 30% where it would seem to take forever to reach redline. If you have faulty pressure sensors on the intakes, faulty boost sensor, faulty wastegate solenoid amongst other things... it could cause no/low or sporadic boost. I guess in your case it's still a good idea to check the vacuum valve, but I suspect something else is going on for sure. Like the C450, the C400 didn't come with ability to build boost when trying to brake boost launch it. Most early tunes didn't add this ability, AMR added this ability first then I think one of the EC locations did next. But I'm sure you'd know if your tune has that capability programed into it. The first tune I put on my C450 didn't.

[@dhillon21]

@@chrisc8089Hey, thank u for the response. I have replaced the vacuum pump valves, but no difference. I am starting to think it might be one of the sensors as you said. My wastegate actuator, like the rod itself, is vibrating like crazy on the drivers side. Do you think that has anything to do with it? I have no codes at all and the boost still comes back every now and then. My throttle isn’t being limited as i’ve been drifting and stuff, hitting redline pretty easily but it just has NO boost smh. My tune doesn’t have the ability to launch either. I don’t really mind that I just want to be faster than 200something HP.

[@chrisc8089]

@dhillon21 yeah it's worth looking into those wastegates and possibly replace them. Some people get the rattle with no issues, but I've also seen some people mention theirs needed replacing. However, also look into the wastegate solenoid it's another part that can have issues and it's not uncommon. The best thing is to figure out a way to log your data, even if using some free app on the android/Apple market. Try to log data because without that, it's really hard to tell.

[@jonrrrrrr101]

@@dhillon21 Hey did you ever figure out the issue? I am having the same issue ;(

[@vladt6038]

Min is never hitting target boost sometimes it goes 9 10 psi other 14 16 psi and it bassicly jumps up and down? Would this fix that? Allso where can I order this from?

[@chrisc8089]

It sounds like the exact same problem, and if so then it's an easy and cheap fix. Search on Amazon or eBay for "m276 vacuum pump repair" and you'll find this connector with a new rubber orange valve for around $30-40. However the same exact part seems to be sold under "Ford Ecoboost vacuum pump repair". I bought one and test fitted it to my spare pump and it was the same but only $10

[@vladt6038]

@@chrisc8089 ok I just ordered it on ebay, thx for making this vid I've been chasing this boost leak problem for awhile looking at every coupler etc not understanding why boost jumps allot and can't wait to get it fixed 👍

[@chrisc8089]

@@vladt6038 yw, I had spent months trying to figure out why my car was not getting full boost and bad times. I checked every other thing I can think of and replaced several parts. I finally narrowed down to the vacuum pump. But the whole time I didn't really suspect the pump, I knew the pump itself should've been OK since my brakes are still working the same. And of course, it turned out to be this one way valve on the vacuum pump for the turbo wastegates.

[@vladt6038]

@@chrisc8089 thanks allot man this was is an insane diagnosis that you found this 😁 I actually just managed to change mine today and when I took it out the orange rubber inside was actually hanging out inside the pump and I had to pull it out and it was all hard plastic disintegrating. Nevertheless put the new one in and now my car boosts like crazy.

[@chrisc8089]

@vladt6038 that's great to hear!

[@MarcoAlcn]

Which tool did you used?

[@chrisc8089]

I recommend to use a mini ratcheting tool that you can attach a torx bit to

[@kiki20604]

does it feels slow in 2nd gear also? and slow when pres gas at 150km/h in 9th gear?

[@chrisc8089]

2nd gear felt normal when doing a run from a dig. When I was just cruising along in traffic there's some initial lag going full throttle, but it was barely noticeable. I didn't even realize it until fixing it. Partial throttle boost while in traffic was lower by about 1-2 psi. These were the typical symptoms in any gear. Not sure about the 9th gear at 150 km/h, I don't typically drive it that fast. Btw I have the 7 speed in mine (2016 C450). From my experience with this issue.. Generally, once the car is already revving higher, then the damaged vacuum valve won't really be much of an issue since there is enough vacuum generated by the pump for the wastegates to still operate properly. The vacuum pump is connected to the end of the camshaft and rotates with the motor. The valve helps to hold vacuum in the hoses going to the pressure transducer which operates the wastegate. The wastegate is actuated by the vacuum. It was mostly noticeable at low speed/RPM and when trying to brake boost launch the lack of vacuum threw things off for the entire first gear - causing boost fluctuations and boost never exceeded 10 psi.

[@kiki20604]

@@chrisc8089 Thank you for information, i order new pump and i hope there will be some diference... maybe i feel most diference in 2nd gear because my c43 is stage3 tuned 520hp 780nm... and mercedes servis told me that my pump do not make any presure... sory for my bad englis haha

[@chrisc8089]

@Marcel levanic you're welcome. Also keep in mind that the "pressure transducer" is another fairly common part that fails in our cars, so that might be the next part to check if the vacuum pump doesn't fix it. The dealerships only sell whole vacuum pumps and not the valve unfortunately. But at least we can get it online. What are all of the mods you've done to yours? I'm very curious 🙂

[@kiki20604]

@@chrisc8089 Presure transducer is okay i check it last week, so is almost 99% that is vacum pump. Remap, downpipe, resdelete, mst intake, weistec hybrid turbo... and is much faster then stage1 tuned f82 m4... Now i have to start the visual rework haha, because i want it look more agressive

[@chrisc8089]

@Marcel levanic nice! If you have an Instagram of your car I'd love to check it out. As part of the turbo upgrade, Did you also upgrade fuel pump by chance?

[@calikickzt]

I’ve been noticing the same issues (2015 C400) I took the valve out and mine had the same black O ring but there was no orange membrane inside of it…. I’m thinking than can’t be good.

[@chrisc8089]

The orange valve likely tore to pieces over time, and the vacuum pump would've chopped it further. But I wouldn't worry about that. I did see the pumps have a metal screen where oil flows but i wouldn't suspect the tiny pieces to clog it. On mine there was no clogging. The orange piece is fragile it seems.. I'm sure the pump would have noticeable issues if that were the case. You aren't the first person to report the orange valve completely missing, and in no case have I seen it be an issue other low boost

[@calikickzt]

@@chrisc8089 quick update, I got the replacement valve and a cheap endoscope from Amazon and of course I found the the black plastic cap and what was left of the rubber valve inside the pump, fished them out with a paper clip. Car is shifting faster now, everything seems to be working better, even the breaks.

[@chrisc8089]

@calikickzt that's great to hear!

[@guillermolrd]

Amigo donde la puedo comprar en españa?

[@chrisc8089]

Try eBay www.ebay.com/itm/115045707705?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=WNmZrqelQ1K&sssrc=4429486&ssuid=zhNR6hqWTti&var=&widget_ver=artemis&media=COPY

[@Catalytic__]

My boost sometimes doesn’t engage at all, boost doesn’t fill and when I gun it it’s super slow seems like turbo isn’t working at all. And I’m stage 2 tuned.. Could this be my problem what do you think?

[@chrisc8089]

Boost not engaging at all? Have you had the ECU scanned to see what underlying codes might be set? It could be many things, including this problem especially if the vacuum lines clogged with oil. But I have a feeling it's something else Do you have aftermarket intakes? I've ran across a problem once where my throttle was limited to 30% and the diverter valves were commanded open, making the car feel extremely slow no boost. Also RPM was slow to climb.. except that I also had CEL in this case.

[@Catalytic__]

@@chrisc8089 hey thanks for the reply back boss. So it SOMETIMES works great half the time it won’t give me boost at all ! Also it is making a rattling noise couple of friends said it might be my waste gates.. I also have stock intakes. I already ordered this part online and will try this first before taking it to service

[@Catalytic__]

@@chrisc8089 I took out the valve and it has oil around it. Not sure if that’s a indication that it’s bad

[@chrisc8089]

@amgc4392 oil around it is normal, and as long as the round orange valve itself is intact, no pieces missing then it's good. A lot of guys have wastegate rattle problems on this platform, but I've not seen them report having boost issues. The bypass flap part of the wastegate that's in the exhaust stream is typically where that rattle comes from. It's difficult to diagnose these types of issues without scanning the ECU or looking at the live data. Is the rattle noise present all the time or only during the lack of boost? Any other symptoms you've noticed, or specific driving conditions where the problem occurs, or is it just random?

[@Catalytic__]

@@chrisc8089 understood I will do it tonight and check.. And it’s all the time! I noticed its gets really loud when I’m sports +…. but on comfort mode it is a light mild noise.

[@TwinsTubeTV]

What would happen if the diaphragm is inside the pump hole

[@chrisc8089]

It may get sucked into the pump and will likely just become chopped/grinded up inside of it. I believe that's what's happening anyway as it disintegrates. There's a screen on the pump for oil to flow, the screen can become clogged but it's not likely happening or an issue. Mine had none of the diaphragm clogging it, but I did see a very thin amount of old oil that was hardened slightly clogging it. If yours is stuck, I'd try to get a fine picking tool like at autozone or pep boys and try to grab it out

[@trinibad_amgc43]

Was your boost jumping up and down ?

[@chrisc8089]

Yes that's exactly what was happening. Immediately after a brake boosted launch the boost would drop, then jump up and down never exceeding 10 psi. Once it shifted to second the boost was back to the normal and expected range

[@trinibad_amgc43]

@@chrisc8089 did you ever get it fixed ? I wondering what I have to fix. Boost pressure sensor or vacuum pump ?

[@chrisc8089]

@TRiniBAD_AMG yes in this video is the part to replace. The diaphragm to the wastage vacuum was disintegrated, there was almost nothing left of it. So the weak vacuum was causing the low boost. You may just need the diaphragm/fitting replaced. You can find these on ebay, if you search for w205 Mercedes vacuum repair www.ebay.com/itm/115045707705?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=WNmZrqelQ1K&sssrc=2349624&ssuid=zhNR6hqWTti&var=&widget_ver=artemis&media=COPY

[@chrisc8089]

@@trinibad_amgc43 I already repaired it before making the video, so my valve in the video is perfectly normal since it was already replaced to fix the issue

[@c43sedan]

Mine does this and doesnt go to the full 375 hp on the dynamic select screen, i have no check engine lights, scanned ecu and no faults. about as fast as a 2008 honda accord..lol doesnt pop or backfire in sport+ either. Boost doesnt jump up or down, it just wont go passed 220 horsepower on the digital gauge..

[@chrisc8089]

Sounds more like a malfunctioning exhaust valve, if you have the performance exhaust? If so it may only come up on a scan using a professional scanner that can read Mercedes specific faults

[@c43sedan]

@@chrisc8089 No performance exhaust , the ecu controls my pops. No dtc's in ecu or tcu. I feel lile its the acuators

[@c43sedan]

Cracked crankcase breather hose under intake plenum, full power restored

[@c43sedan]

Car wont pop or backfire if theres a vacuum leak no matter how minor

[@chrisc8089]

@@c43sedan that's good to know! Thanks for the update I'm sure it'll help someone

[@The_McD]

What was the mileage on this car? Did it throw a code? Curious how you identified it.

[@chrisc8089]

I bought the car with 32k miles after someone leased it for 3 years, tuned it at 34k miles. Never did any 0-60 mph testing until around 36k miles which is when I noticed something wasn't right. Around this time I also installed a boost gauge and did some basic logging of boost, afr and other things. The valve could've been bad even before I bought the car and I just never noticed. No code.. ECU doesn't even monitor the vacuum on this line. Basic troubleshooting on and off over some months. Checked everything I could think of, but the last thing I considered to be a problem was vacuum pump. Brakes were working fine and so I prioritized troubleshooting other areas first. One day I also had a friend come over with the same car and tune, we did some back to back testing and monitoring of boost for the sake of comparison. This is my first Mercedes and I was also still a bit unfamiliar with this platform.

[@The_McD]

​@@chrisc8089 - It could have been a manufacturing defect. When you make tens of thousands of parts there will be bad ones although low numbers. The tune does add more stress on internals and components. Is the tune a JB4? Would be great if you could update down the road. I'm looking at buying one in the next week. Thanks

[@chrisc8089]

@The_McD I went with AMR for tuning. Started with ECU then got the TCU done a year later. My 0-60 times went anywhere from 4.5s - 4.9s before I replaced the vacuum valve. Which is practically stock times, but from a roll the car felt very noticeably faster. It was only trying to brake boost launch the car where it was noticeable that my 0-60 times were terrible. After fixing the valve I ran a 3.70s, and a couple 3.76s 0-60 dragy runs. For reference this is a C450 so it has the 7 speed transmission, and also the tune map is for 91 octane gasoline.

[@phillip7925]

😄 ᵖʳᵒᵐᵒˢᵐ