S-Prihadi

Gang,

Those with this M276DELA30 engine, your turbo boost leak path are :

WASTEGATE
01a. ACTUAL LEAK : Wastegate metal flap inside the turbo can't close well due to the arm worn out and shaky shaky.
Google BMW engines, good case study on youtube

01b. LEAK INDIRECTLY CAUSED BY OTHER COMPONENT : The turbo boost solenoid including its related hoses controlling the wastegate vacuum flap leaking or fail to pull the rod, which means boost will escape.
The design is fail safe, loose boost instead of overboost and engine computer intervene by cutting fuel & killing injector and limp the engine, example M271 EVO which is not vacuum operated flap, but positive pressure.
https://mbworld.org/forums/e-class-w...te-issues.html
https://mbworld.org/forums/e-class-w...76-3-0-tt.html

01c. LEAK INDIRECTLY CAUSED BY OTHER COMPONENT : The vacuum flap is leaking, so no negative pressure built up = no suction = no pulling of the rod, which means boost will escape.
Search Taso's channel https://www.youtube.com/c/TasosMosch...uery=wastegate

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02. Diverter valve failure. https://mbworld.org/forums/e-class-w...-0tt-m278.html

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03. The check valve I am discussing now. Its vacuum opening behaviour is still good, but whack with pressure, it leaks.



What does it actually do ? Its in a lousy place. It can be under boost or vacuum, unlike in normally aspirated engine's check valve which work under less stress.













We must by as a set to the pipes





So, I only use the check valve and keep the rest for next time use. This is plastic, it will crack soon , my car is no 8 years old.



Happy tracking leaky leaky......

S-Prihadi

The 3 possible boost leaky zones are worthy of mention because they perform repeated open/close function and is subjected to wear and tear.
Surely there are many areas like gasket, o-rings, air hoses which can leak the boost too, but those are static duty and tends to last much longer.

The leak is slow but as it is, it may effect long gear pull like 3rd and 4th gear ( top speed ).
I wonder if the check valve simply OPEN, what will happen during a long gear pull and boost goes in to engine crankcase ,
what will happen to the crankshaft oil seal and other related components which is not supposed to receive positive pressures.?
Perhaps the other pipe ( #2 in the CAD drawing ) from the boxy shape oil separator which run to the inlet of the Right side Bank 1 turbo will take those excessive pressure ?

We know if PCV valve stuck closed and induction/suction by inlet manifold for those gas can't happen , bad things will happen.

DubVBenz

Thank you for this writeup. I see you bought the pipes, so that means you had a crack and leak right? I have an OM642 and the charge pipes (also plastic/rubbery stuff) crack and break open as they age. It manifests itself after the engine is hot and you've run it WOT in higher gears (like flooring it on the freeway). In those scenarios you get a limp and a code. What symptoms did you experience to lead you down this path, and how many miles do you have now?

S-Prihadi

Hi DBenz,

Nope, my pipes are still healthy for now, no crack. No DTC.
It is just a routine health check where I will test all check valve/s I can access for its 100% CLOSED position capability and if it will flow/OPEN under suction with ease as it should be. I am now at 36,000 KM.
If you see the Utube video of mine, I am showing a simulation of 12 psi turbo boost my engine is capable pushing thru that check valve and it is super minor leaking back to Oil Separator/PCV at the moment, hence I replaced it before it becomes really leaky.
That check valve is a twin check valves in one.




Before boost build up, air path 1 in pink is from the oil separator ( PCV ) system and engine at inlet manifold will suck air path 1 and 2.
Air path 2 is fuel vapor purging from charcoal cannister which has its own electrical solenoid to open/shut the flow.
Air path 3 in blue only happen under boost or above ambient atmospheric pressure caused by turbo boosting up.

Any mechanical components in my car I keep it as much possible close to a VERY like new working condition, because they are measureable/test-able, unlike electronics components which I need to wait for it to go banana
Daily drive on this car is logged per 1 second using Banks Data Monster Gauge via OBD2. Once in a while I will scan those excel logging files to spot possible problem brewing.
After a long distance run , say Jakarta-Bali or return run, I will study those files carefully due to 10 + 10 non stop hours the engine run ( excluding fuel stop ) in 2 days, so total 20 hours.

Soon I can log more data, I am going to put extra sensors like Engine Oil Pressure which is so important but non AMG engines do not get one...DUGGHH !!!

groovetek

Hi, great thread. Wondering your thoughts on the symptoms with my E43.

So it recently got Stage 2 tuned, so obviously running more boost, probably exacerbates likelihood of these types of issues.

Anyway the car has been driving fine, boosting strong from low rpm, etc. however on a drive yesterday, upon spooling from low rpm (around the 1500rpm to 2500rpm range), I suddenly felt a loss of boost, and can hear alot of air "bypassing" kind of sound.

Strangely, if instead I go full throttle starting at higher rpm, say 3000-3500rpm, then it still boosts quickly/strong and holds boost.

So something appears to be opening an airflow path when getting on the throttle at low rpm. I replaced the small check valve off the vacuum pump at the rear of the engine as part of the Stage 2 upgrade recently, so I don't think that's an issue.

I've also had a look at the main hoses from turbo outlet to intercooler, intercooler to throttle body, etc. and all seem like they're on solid.

What would your gut feel say is causing this issue?

S-Prihadi

Your engine is 396HP version M276.8 right ?

Some questions :
01. When you say you loose boost, are you watching your boost or the power surge feeling is what you define as boost ?
02. Stage 2 tune. Is this ECM flashing with new parameters or is this the cheating version fooling the pressure sensor kind of mod , the add on module thingy?
03. What is your mileage now ?

Since your engine is tuned, I am trying to visualize how the new tune torque curve is like ?

In my engine, being a family sedan version M276.820 , the turbo boost peak is not at redline RPM, it is at much lower RPM.
I call this engine a city-engine , nice engine for traffic jam laden city of mine.

Let me know those 3 questions yah

groovetek

01. When you say you loose boost, are you watching your boost or the power surge feeling is what you define as boost ?
Watching the boost using an app the boost start to build a little bit then I can suddenly hear diverting of air, surging from around 2000rpm. But once I get to 3000rpm it clears up and suddenly all boost comes back.

02. Stage 2 tune. Is this ECM flashing with new parameters or is this the cheating version fooling the pressure sensor kind of mod , the add on module thingy?
This is a full remap with all parameters, no fooling of MAP sensor, etc. it was running fine/strong until only 2 days ago, boosting 1.3-1.4bar peak in the mid range, around 3000-3500rpm, and tapering down to 1.0 bar by 6000rpm.

03. What is your mileage now ?
Quite high, 118,000 kms. It had new factory spark plugs installed end of last year, just 5000km ago. I only bought the car a few months ago.

Thanks so much in advance for your potential insight as to what could be going on. I tried applying some light pressure (using my mouth) on that 3-way check-wave and it was holding.

I'm suspecting DVs because of the mileage of the car, plus the way the DV holds closed is by equalizing boost on either side of the piston right? So I wonder if at lower rpm, there is not enough boost to keep the piston closed, if it's degraded, etc. but at higher RPM, past a certain boost level it can push on the backside of the diaphragm to keep it closed.

S-Prihadi

Wow 1.3 BAR. Mine is 0.8 BAR , but only 330HP stock.
There is much more stress to the components, no choice, pay to play.

You have vacuum hand pump ?
Get this one, which can do positive pressure too :
Since you said that boost can be OK at higher RPM, we shall assume the wastergate metal coin/flap is OK.
This flap :


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Lets check these 2 :

The two moving parts controlling boost is the vacuum actuator and the boost control solenoid.

Vacuum actuator





Use the vacuum hand pump to suck it in, see how many Hg or negative PSI it takes to fully pull in and does it hold still and no leak for 5+ minutes ?



Turbo boost control solenoid.


While you can test it for leak, you can't easily test this for strength.


This is a simple valve controlled by PMW signal.

NOTE : To test the boost solenoid Y77/1, it must be on the road and turbo while boosting. Idling test is not accurate.

..

The higher the boost targeted, the more power in % PMW this solenoid get.
The actual power is vacuum power from vacuum pump, but this solenoid is controlling it so that the vacuum actuator round thingy get higher and higher suction negative pressure to fight the boost.


If it has 100,000KM+, you best replace this solenoid. It is cheap anyway.
Its failure or weakening is lack of precision to control the vacuum flow. Or if totally dead, it wont allow vacuum to pass thru.

While at it, test by vacuum pump the 2 vacuum hose/tubing set controlling the wastegate. Are they lealking or not ?
Item #20 and #10.






Also while at it, run engine and read the vacuum pump value for the turbo boost solenoid.
If you don't see at least -13.5 PSI from your vacuum pump after a few engine revs, that is a bad vacuum pump already.
I have electronic sensor installed for my vacuum pump, so I can in real time see its performance and log it. I worry for my brakes, not my turbo boost.

=========

Actually, you can if you want, read the vacuum pressure into and out of the boost solenoid, but you need two sensors and a scope, which is too expensive.

Here is a good video of a VERY weakened boost solenoid, not totally dead, but weakening to the point DTC is issued by ECM


Happy troubleshooting.........

groovetek

Thanks @S-Prihadi !

I went for another drive today, and felt like when the car loses power, I could hear the exhaust note sounding different, indicating a wastegate scenario.

Also, on a few occasions, the car would suddenly tighten up and boost hard. With that in mind, and with your advice, I decided to look into the boost solenoid.

I found that the amount of vacuum on my finger from the vacuum hose at the valve (from the vacuum pump from rear of engine), felt quite alot stronger than at the "out" port on the solenoid. Also when putting my finger over the out port, the solenoid would make a funny buzzing noise.

I took the valve off, gave it a good clean, some oil came out, ran some IPA through it, re-assembled it and the problem has stayed away even after an extended drive.

I've ordered a new one for good measure; I'd imagine it's slightly degraded by now after 118k kms, and with abit of contamination from oil vapour from when the vacuum pump check valve was split.

Thanks and will update if situation changes!

S-Prihadi

Aha, oil in the boost solenoid. So at one point in time that small membrane at the vacuum pump fitting for turbo boost solenoid, gave up and hence you got oil.
Mine is dry so far, but me only 40,000KM today, albeit 10 years old.
I bought spare check valve/fitting from Amazon, but I do not know its quality.

The buzzing sound from boost solenoid is indication that the valve mechanical movement is not smooth anymore.
Since it is using PMW and at 300Hz, its like Bee's wing buzzing when and if mechanical resistance is hindering it.

Here is a test I did in 2022.




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Groovetek wrote :
I found that the amount of vacuum on my finger from the vacuum hose at the valve (from the vacuum pump from rear of engine), felt quite alot stronger than at the "out" port on the solenoid.
.
The ECM will pulse the PMW or power to boost solenoid just enough to maintain boost or not allow the wastegate flap to leak.
So it will not use a 100% of the -14.5 PSI vacuum available from the healthy vacuum pump.
You can see my video, at 40% ish duty cycle at idle, the vacuum at the output side of the boost solenoid is only -10 Inch Hg or approx -5 PSI.
At 90% duty cycle which is MAXIMUM, it is showing 26 Inch Hg or -12.7 PSI.

So the suction power of the boost solenoid output is dependent of ECM PWM command %.
Best to use Xentry or proper scanner to do this test, don't do direct battery voltage to boost solenoid if you can, the coil can overheat.

Also every extra length of hose or air-space further away from vacuum pump, it will be weaker vacuum power at that extra distance.

Wastegate flap wear and tear is given, it will happen. The main rotating shaft is the one taking the beating, not the round flap itself.
Google BMW wastegate repair in youtube, there is a lot of examples.

groovetek

Fantastic information - thank you. I can see you're not only a true guru with the M276, but you're also someone who takes pride and joy in sharing your knowledge and guidance to beginners to this platform!

I felt that way with the B5 S4 2.7TT platform, back when I was building custom Stage 3 cars for multiple customers - I knew practically every map in the ME7.1 ECU, and where every vacuum/boost port and connection was, ha.

By the way, I tuned my E43 myself from a stock binary file; luckily there hasn't been that much chance in Bosch FR from ME7 to MED17, so most of the same tuning concepts exist still.

S-Prihadi

Me IT stupid.....
I hate computers and software thingy.....
But have to learn them, no choice.
I dare not even use Vendiamo, afraid I will brick my modules.

Get to know your E43 while it is still healthy, otherwise when trouble happen we do not have a baseline.

I have some testing done on COP, High Press fuel pump quantity valve and injector using pico scope, if you need them in the future to compare a known good waveform, make a post to request it, I will share with you.
Cam vs Crank timing waveform I have it too, for future reference.

groovetek

Thank u so much for offering to help.
​​​​I'd like to ask you something; is it normal for wastegates be pulled closed at idle on M276?

I feel like in idle, it makes sense for wastegates to spring return to open position? No need to spin the turbine, and allow minimum restriction to exhaust path?

Anyway I have a replacement Pierburg solenoid valve from a 2016 SL63 with only 15k miles, should arrive tomorrow. I thought better to get a Pierburg one than cheap Chinese knockoff?

Or in your opinion or experience do you think the Chinese ones are ok/good?

​​​

S-Prihadi

Stick with Pierburg or MB-Pierburg boost solenoid and not Chinese knock-off. They are precision device. They last long and low cost, what more can we ask.

Don't worry about feeling like an indie, we all want to learn... I learn a lot from other members here and good youtube channels and my own itchy hand testing this and that on my engine.

The standard ECM parameter for wastegate is fail safe, no power or no vacuum, wastegate stay open by the force of the return spring inside the vacuum actuator, that fat apple shaped thingy.
The wastegate flap itself is a slave, it only follow where the vacuum actuator movement is, vacuum powered pull or spring powered push.
In M271.8 inline 4 turbo GDI W212 E200/E250 or W204 C250, the wastegate uses POSITIVE pressure from its own boost and not vacuum, but has boost controller solenoid too.

At idle the M276.8 and M278 wastegate flap is to be closed just nice and proper, no leak.
Turbine blade may actually offer worse flow for exhaust gas when it is stopped dead, instead of simply spinning with exhaust gas.
On sailing boat, when no more using its small diesel engine for maneuver in a marina and use wind power instead in open sea, the propeller can have the blade angled/folded to reduce drag...as though as there is no propeller.
Like this : https://www.flexofold.com/

Update me when you have replaced the boost solenoid