Chevota

I have a '16 E550 Coupe (M278 eng), 32k miles, and it's lost a ton of power and I don't know why so I'm hoping someone has a clue.

It had 28k miles when I bought it some 4-5 months ago. It ran fine and I put an OE tune in it and was pretty happy with that. It it sure felt like I was getting the claimed power and acceleration, might even be described as violent. Seemed fine for a couple months but then I noticed it just wasn't pulling hard anymore. I rarely get to floor it for more than a second or two due to traffic, but in that time and especially at higher rpms it's clearly lacking big time. If I had to guess it's making about 50-60% of the power it was. No check eng light but I scanned anyway and nothing... Scanned again several times since, including other apps and dongles, nothing. So I uninstalled the tune just to see, and power dropped even further and most certainly well below what it had before the tune. As a comparo, I had an E350 before this and I'm pretty sure the 350 would win in a drag race.
So I got Torque Pro and Realtime Charts to look for clues. With the OE tune boost would peak ~15psi at low rpm, like 2500, but it's just a brief fraction of a second spike then quickly drops to ~10, then drops more with rpm. I do not feel that brief spike in power btw, it only shows up on the app. With the tune removed it peaks at 8psi at low rpm and drops to <3.5 or less at it's max of ~6200... I get that the turbos are too small for it but not that small, so this seems like a controls issue or something is preventing them working? This is my first turbo car so I'm no expert, but I'm not stupid either. So I'm guessing whatever controls the wategate or bypass is simply commanding them open when they shouldn't which would explain the brief peak as it tries, then quick drop as it controls it to do so? Since the psi dropped more with oem vs OE tune I think I can eliminate leakage in the system b/c with a leak the pressure would've been the same.
I'm tempted to hold the wastegates closed to see what happens, which I don't think will hurt it but it's an expensive engine and turbos so I'm asking first. Plus the power drop is greater than the difference in boost lost so I don't believe it's simply a lack of boost, I suspect something else and the boost drop is a byproduct. PSIA (I said A) at peak oem boost is claimed to be ~27.5. My current peak psia is ~23, a loss of ~16-17% which cannot cause the massive loss in power I have... What the oem boost is at 6200 redline is I don't know so no comparo but I bet its not a whole lot higher than my 3.5psi.
Someone mentioned I should suspect the knock sensor, which it has two of and they're a pita to get to. My understanding is the knock sensor only pull timing, not boost? And if one or both failed I'd assume it would simply allow ping/knock, if there was any, and most certainly give an error code? Or could they somehow give more signal and say it's pinging when it's not? Ign timing with the OE tune would go negative under say peak down to ~10psi boost, as much as -10 degrees, but w/ the oem at 8psi it just goes down in the single digits, like 5 degrees advanced. Seems like a big gap in timing for the small boost difference. With less boost, like at 5psi, timing is 20. At 3.5psi it's 23 which I suppose sounds normal but I just don't know what's normal.
Sources online say you'll lose mpg if it was a knock sensor but that isn't the case here, my mpg has not changed and I get better than the factory claimed 21 despite my driving style, which is a rare day that anyone accelerates or drives faster than me so I'm either passing people or stuck behind them. 99% it's the latter but the point is I think I'm getting exceptional mpg...
The Relative Throttle Position, which my understanding is actual position, never exceeds 75%. I think that's ok considering how big it is, but should it not open all the way anyway? I mean why install one so big that it never needs to fully open? I have no MAF so I can't tell you air flow. I've been using the app to look at TQ, HP, MAP, Intake Temp, Throttle Pos, Ign Timing and Speed. Nothing else seems applicable. The Intake Air Temp is much higher than I expected at ~120 on up to 160+ at low speeds, but even when it's down ~80F on a cooler morning the car runs no different at all.
Anyone have any thoughts?
Thanks in advance for taking the time to read all this.

Heathlewis

Did you ever get this solved? The same thing happened to me today. Sitting in traffic, made a u-turn, hit the gas and noticed maybe a 200 hp drop. I also have an OE tune. 81k miles. Has always ran flawlessly until this incident. No CEL. '14 E550

Chevota

No I have NOT, and I'm very frustrated.... Stuck with an expensive hotrod that has no power, no clue why and no solutions...

Since I posted last I rigged a camera under the hood to watch the wastegate on the pass side, and as soon as I floor it it opens. This would explain why I get a brief moment of pressure before it drops because it apparently takes a moment for the computer to decide to open them, then time to physically open.
Still, the power loss I have does not match the pressure drop. I'm not certain what the OE tune pressure is but when it's reading say 8psi boost the power is a joke compared to what it was. As mentioned it seems about identical to my old E350, which made a claimed 302HP and 273ftlbs torque. According to the Torque app I currently cannot break 300HP or 300ftlbs torque. Of course the app is not very accurate but it seems about right compared to the E350. The engine is 1/3rd larger so even with no boost it should make good bit more power, but no, so obviously something else is up, big time.
I've considered locking the wastegates closed just to see what happens, but if it doesn't make power at 8psi then it isn't going to magically make it at 13 or whatever.

In an attempt to troubleshoot I added a bottle of VP octane boost which I est took it to ~95 or so, which made no more power. Of course that doesn't mean much, it would only mean something if power improved. I do not want to replace the knock sensors ***** nilly because it's kinda a big job but more importantly it's a bit risky. If I break some stupid plastic part that's important I'd have to rent or buy a car within a day. More than that I just don't want to because I just don't want to. If I had more reason to believe it was the knock sensor(s) I'd have them out right away.

I'm sorry this happened to you too but it makes me think it's less of a weird glitch and more of an OE thing? Or just some weird whatever issue and we both happen to be victims, but odd we both have OE... Whatever it is it's probably easily fixed if we knew where in the haystack the needle is. Frikkin computer controlled cars are such a pita. Everything I own that's electronic is a pita, usually don't work right and very short lived. My phones and home computers included. My laptop is apart on the floor right now, apparently a dead screen. I have three other laptops that all worked when last used, but none worked today when I needed one so I had to repair the one I'm on now so I could order a new screen and yet another laptop. Gremlins apparently love me...

If you find anything or have any ideas please share asap and I'll do the same because I want this over wth asap and I'm sure you do too.

bbirdwell

Have you read out the codes both stored and current? If yes, what are the codes, if any?

Have you logged data real-time? If yes, post some logs.

If the above answers are no, you won't get anywhere until you can answer "yes" to the above. Without the above info, you are not drilling down to the root cause of the problem. The solution will be very simple *once you know the root cause*. Based upon your posts, there is no information to provide a clue. I have no idea what you refer to as "OE tune" but all of your problems started shortly after you installed it. Is "OE" Original Equipment (i.e. Mercedes factory tune) or is "OE" an aftermarket vendor? If the latter, return to the OEM tune and compare the performance issues.

So, is an "OE tune" a Mercedes factory OEM tune or an aftermarket tuner program? If the latter, return to factory tune.

Not trying to bust your ***** but I used to tune aftermarket ECUs for high-performance Miatas. An unintended "little" error could cause a major performance issue that would have me chasing my tail for days or weeks trying to resolve.

Chevota

bbirdwell: Nothing that involves electronics in my life is easy, and it may be very simple once I know the root cause, but finding the cause is the problem with electronics... It's not like OBD actually works or something. It's a very crude system that's like a Weather Rock, if you've seen one, except in this case you cannot see the rock. More often that not, for me, OBD gives false codes or no codes when there should be. Around 2008 was the last, and maybe only correct OBD code I've had; a faulty O2 sensor, otherwise it's all BS. Maybe not for most people, I'm saying for me. The usual response I get from any electronics mfg, tech support or whoever for whatever device is "I've never heard of that before" which gets real old.
In this case there were no codes as mentioned unless you count U codes like a comms error with the pass seat headrest or the light bulbs I pulled because they're annoying.
OE is the name of a tuner, and as per the first post it was removed first thing which only dropped boost and power even further. The tune remains removed while I try to figure this out, but like past experiences involving car electronics, the only fix is to get rid of the car.
If you want a chart you would need to specify what you want to see, but boost is low, power much lower. I'd post a random chart now but as mentioned yesterday I'm having serious computer issues, more so than usual. This is my life when it comes to electronics, which is why I have many backups for anything important but I do not want to buy a spare E550.

SALES@OETUNING

Have you taken your car to a MB certified tech for diagnosis? We recommend running a diagnostics for injectors, spark plugs and coils. These are common issues for service. Only Xentry tool can perform the necessary diagnosis tests.

Chevota

OE; thanks for the input.
I'm considering it. The only time I've taken a car to anyone, other than alignments and tires, is one Benz to the Benz dealer for something I could not figure out, which also had no codes. They couldn't figure it out either... I fully expect the same results this time but I will take it somewhere as a last resort.
The car only had ~30k miles when this happened and according to my cheap Autel Maxi AP200 all that stuff is fine, but I'm new at using it so who knows. No misfires per Autel, and I've never felt or heard a misfire. It runs perfectly other than the power is low, and I bet if I traded it in at the MB dealer it would pass a test drive.

I don't suppose you know what I should look for using a generic OBD scanner or the Autel? I mean other that what you already mentioned. Other than opening the wastegates when it shouldn't I can't see anything else out of whack.
Is there some place people share charts on cars that run right so I could compare? I didn't see anything in a google search...

Heathlewis: I don't suppose you have charts before your car took the same dump?

SALES@OETUNING

Like I was saying in the previous post, only a trained MB tech with Xentry can perform the required tests/actuations for diagnosis. Unfortunately generic OBD2 is very limited on this platform.

Chevota

An Xentry diagnostic, per a local place that has it, said they'd need the car all day. So that's not going to happen since I need it, and my wallet won't open that far for a diagnostic. I was thinking it would be 30min and $100, not >$1k!
Meanwhile, bbirdwell wanted some data, so here is as good as it gets from my best obd dongle. Same run from ~30 to 70mph in 3 charts, 0 to 6000 to show rpm, -10 to 280 to show power, and -10 to 80 to show boost and what not. Torque's Realtime Charts will not reduce the rpm scale, it is set at .1 here, also tried .01 but nothing, plus tried it on two devices and three dongles. Time marks are supposed to be 100ms but that would mean I went 30-75mph in <3sec. So that and the sync for each data is always off but the sync in this chart is pretty good, hence me saying as good as it gets. Just classic electronic bs not doing what it's supposed to do.
<280HP, <260TQ with 5 to 8 psi boost. This is with the OE tune removed, so 100% stock except for K&N air filters, 91 octane, est 65F outside and 2nd gear until mid chart.
With the OE tune power was a little higher, like 20%, and boost would go to 12, not 8, but would follow the same path degrading with rpm. With OE it will sometimes flash for a moment to ~17 psi, only to be controlled back to 12 as soon as the wastegates open which is very fast.
At time marks 16 to 23 you can see peak boost drop with rpm, then when the throttle closes a bit (not my doing) the boost comes back. I probably had it floored from mark 1 or earlier since it takes a sec before anything actually happens, and held it to ~mark 33. The throttle at 75 is fully open, per a mechanical test via Autel.

Barbalatte

Hay mate we’ve been speaking about something over in the C63 section. After disconnecting the rear exhaust flap sensors the car would drop to a much reduced power as a fail safe. Worth a try. One may have become loose.

Chevota

Barbalatte: I don't believe I have ex flaps/valves. Not that I looked for them but when I had it up on blocks I would've noticed something like that. Plus I googled for it, like replacements, and nothing comes up. I will look again though and I appreciate your taking the time to share possible causes.
I wish there was a list of what the computer does to cut power, and what causes it to do it so I could narrow down my search. All I can see so far is it's simply opening the wastegates way too soon. As for timing and throttle position I can only speculate because I have nothing to compare it to. They're certainly not where they would be if I had programmed it but I don't know what the normal smogged down and safe map looks like. Sometimes the timing looks normal, like 20 adv under my weak boost (I assume 20 would be normal), then other times goes negative quite a bit and I can't explain that. The throttle opens all the way, but then a fraction of second later closes to random levels, like 70-50%, then opens, then closes over and over. Apparently, somehow, this is the tranny's doing which I don't understand, meaning why is the tranny involved in eng operations. It's like an old hag in the back seat telling you to slow down but in this case the ECU listens.

bbirdwell

Sometimes being a bit color blind sucks when trying to look at multiple overlays on one chart...

Assuming I'm not screwing up the colors, it almost looks like the throttle position line is offset to the left a few ticks when compared to the horsepower and torque. If I visually shift it to the right a few ticks then things begin to line up (just hypothesis here). Torque and horsepower max out, throttle cuts a bit and horsepower and torque drop a bit, throttle reopens, horsepower and torque increase, and the throttle cuts back again. Kinda hard to collect this data on the street; might be worth some time on a dynometer depending upon how much you like the car.

The transmission control module influences the throttle to close when the torque exceeds programmed "safe" values. Any chance there is a software update available for the transmission control module? I'm beginning to think it is the "smart" transmission pulling back on the throttle...

EDIT: Now I'm thinking the horsepower drop I see around tick mark 28 is caused by an upshift...

Chevota

bbirdwell; thank you for your input. Yeah, as mentioned this is a good chart, most are offset even worse. So you have to move them around in your mind to put them where you think they should be. A dyno would be interesting but it'll just show the obvious which is the wastegates are opening too soon/too much. They seem to be trying to hit a certain psi, like the MAP is bad and giving a higher than actual #, but I'm reading the MAP too so it is not. Plus if it was the MAP it would/should cause the fuel to go very rich, but instead it runs perfectly.
I also have some charts where I put it in higher gear, like 4th, but start at <2kprm to let it come up more slowly to give the stupid system time to collect more data. Same deal, wastegates open and let my power escape out the holes... I believe the wastegate modulation is working because it does try to hit a certain psi, it's just the wrong psi. Reasoning; oem program/map shoots for ~8psi but the OE tune shoots for ~12psi. So it's clearly working, but like a cam that's a tooth off.
Also, I was looking at said youtube videos on Xentry and it doesn't seem like it'll be of much use. Of course I'm only barely youtube certified but it isn't what I thought it would be and seems very similar to the Autel I have now. I didn't see a "no codes but it's hosed anyway" button. Maybe an Xentry guru can chime in if it's any hope for problems with no codes.
I will continue research, I just have very little time to do it... Meanwhile some MB god is supposed to chime in with the answer.... I mean Heathlewis and I cannot be the only ones this happened to and I'd much rather fix it than get rid of yet another car thanks to computer bs.
If you/anyone wants me to chart a certain something under a certain condition to help troubleshoot, let me know... Thanks again everyone!

Heathlewis

No charts and after letting the car sit for a few hours, the problem went away.

Chevota

Heathlewis: Glad to hear yours is fixed, and thanks for the update. Alas, mine is still fubar.
I have an Xentry program now but so far I've found nothing wrong, which is extremely frustrating... I'm a novice at using it and still have some dynamic testing to do so who knows.
Also bought a new MAP sensor (it has 2) and was going to replace the one I believe controls the boost psi, but I can't reach it. I read you have the pull the firewall out, then remove the entire intake which I predict will not change anything. It's hard to stay positive... If I do get it out I think I'll make an extension tube for it so the map sensor is reachable.

Chevota

Ok, I finally broke down and took it to a dealer since they wouldn't stop pestering me about the airbag recall, and everyone online insisting I have to take to a professional for the power loss issue, which I disagree with but I did it. I got a rental car so they could play with it for as long as it takes.
I want to note that I called this beforehand, either here or in another thread about it, but I knew this going in: "They can't find anything wrong..." They took it one a step further and said the mechanic took it for a drive and he said; "it runs fine, no power loss." Wtf?

The tune I've had on it only keeps it running like a V6, which I know because I had the same model with a V6 before this car. So I removed the tune before I drove it to the dealer and I had forgotten how low the power really is, unless maybe it got worse, but it's flat out embarrassing!
Too late to get it today so I'll pick it up tomorrow and we'll see how much I have to pay in exchange for nothing. Once again it appears the only fix is to get rid of yet another Benz due to mystery problems. So frustrated....

Chevota

When I went back pick it up, the shop foreman and I spoke at length, and I took him for a ride to show him. He was very nice and really wants to help fix this, but he too was unable to find anything wrong. They're just like the indie shops; no code, can't help you.
One thing the car did different, which was on the test drive with him, is the CEL came on! First time it's done that for any reason ever! It was low boost turbo #1. Maybe I was right about it have even less power than before? How it can tell boost is low on #1 I have no clue since they both feed into the same manifold and there is no way to differentiate where the air is coming from. It still doesn't help me because the turbos are fine, but he hooked it up again and looked anyway.
He was also kind enough to not charge me for any of it! Not a cent for the whole ordeal. Not that I'd ever need to go to a dealer again, but if I did I'd take it to him.

Today I tried to buy a used ECU online, another desperate attempt to fix it, but nobody will sell me one. They say it's "classified as a Theft-Relevent Part". So I can't buy a part for my own frikkin car... Whatever....

S. Madman

You would not be able to use it if you cant mate it to the rest of the car. Have you checked your wastegate solenoid actuator?

Chevota

I found an ecu on ebay! It's not exactly the same, and from an E63, but the webpage says it'll work. If they don't cancel the order, like mboemparts.com did, then I'll be at step one. Step two; send it out to be virginized. If that works then step 3 is take it to the MB Dealer and clone it to mine, assuming that is possible. From what I read online it's not that easy to do like virtually all other models. So I'm not very optimistic I'll get that far, and if it do there's zero guarantee it'll fix my issue.
If it's simply not fixable no matter what I do, I'll just make my own circuit to control the boost solenoid and whatever the cause is, it can go f itself.

Thanks Madman, but he oem solenoid boost valve cannot cause this issue, but I replaced it anyway some time ago. I wish it was that easy... Keep in mind the ecu is actively controlling the boost to a lower psi, so it's not a hardware issue like a leaky wastegate, leak in the system, clogged cats, sticky solenoid etc.. It's the ecu doing this, but how/why I have no clue. Too bad MB doesn't have a way to tell you when parts fail...

I figured out why the CEL came on at my visit to the MB Dealer: I read online that boost has to be low for 5 seconds. With the tune installed it apparently doesn't drop low enough, and I rarely ever run without the tune because the power is so pathetic. So the pass I did with the MB tech, no tune, took more than 5sec and tripped it.

S. Madman

I had the same problem with no CEL loss of power and it was the solenoid for me. You can easily tell if when you start your car you see your wastegates rods shake. If you have a vacuum meter you can tell if the wastegates are sealing enough if you connect one on the side that connects to the Y, after your wastegates solenoid. Pump to 25 PSI on the tool (emulating what the M278 vacuum pump generates), and if it holds, that part is good.

Next would be after the pump, but before the solenoid while the car is at idle it should create vacuum at 25 PSI on the tool, and hold.

Last optional since you already checked, but just in case you have a bad hose, connect the vacuum tool on exit side of the solenoid, before it goes to the Y. When the car is at idle it should read 25 PSI. If it does not you will need Sentry to actuate the solenoid between the 2 modes 90% and 0%, to see if the solenoid is actuating.

You can also start the car with the solenoid unplugged from the Y, start the car, and while you reconnect the Y to the solenoid see visually if the rods on the wastegates move shut. You have to check each side at the time, because it's very hard to pull that hose from the solenoid while the car is on, and you may break it, so shut it off then back on.

Chevota

Well, what I meant is it cannot cause this particular problem, but of course it can cause a similar problem like yours.
Clues are: If vac was poor or leaking then the wastegates would not respond to ecu commands because it never hits the target psi. The problem would be consistent regardless of oem or tuned settings. Same answer to any leak in the intake system, exhaust restriction or problems with the turbos.
The vacuum is 25" or more, if I recall correctly from >a year ago. The dealer checked it too, and all the lines, which held. I have a dash cam so I got to watch them do it Same dash cam I used to watch the wastegates control to the two different psi #'s of oem and tuned. The wastegates hold closed, then open when I hit the programmed psi mark, then modulate back n forth to maintain boost psi setting which is of course different between oem and tuned. So the simple fact it modulates to oem or tune is the clue that it's the ecu.

Someone told me a chinese KTAG could clone my ECU to the used one, despite conflicting info on the AlienTech/KTAG website saying the legit version cannot. So I guess I'll buy one and see. Then I get to figure out what other thigns I need because I know it won't be that simple.
Thanks

WRC-LVR

In looking at the charts you placed in the thread, i see less than 8 psi boost at most.. Either you have a large boost leak somewhere or the turbos are not making boost,

If the turbo seals are bad or you have a housing leak or crack on the hotside, you are not going to make much boost. if the Bearings are bad or carboned up , the wheels are not going to spin up easily or well at all..low boost ...If you can get to the wheels, spin them with your finger, they should spin easily and the shaft should have no play side to side and very little in and out. If not the case, then id would think you are gonna have to pull them and rebuild or swap them out

Boost testing Make a charge air tester and put about 30 psi into the system testing the system from after the turbos to the intake manifold. make sure to block off ends. and look for leaks using soapy water. If you cant then get someone familiar with turbo systems to test it. With that big a leak you will be able to hear it quite well.

Check out the intercoolers, flex hoses and clamps, one way pcv valves (if it has that ), throttle body gaskets and seals, solenoids for turbos, rods for waste gates, turbo wastegate flappers etc etc Check plugs for soot,

If it has boost leaks then your gas mileage will be poor as the ECu will be adding fuel for anticipated boost but the amount of air will be less than what it should be. Both STFT and LTFT Short term fuel trim and Long term fuel trim % will be way off. You should be able to log that in your OBD dongle scanner using Torque, it is a nice app

Chevota

I don't think my intercooler or intake can handle 30psi, they are not strong like on most cars. I don't believe there are leaks because it can hit as much as 17psi before the wastegates open. The turbos seem to work because they can not only get to 17, but get there before the ecu can catch it and bring it down. So I can get good power for that very brief moment before the wastegates open. It seems the best way to do that is going ~30mph in 2nd and gas it. It'll spin the tires and start to get sideways, but only for maybe 20' or so and power is gone. So it's there, but the ecu won't allow it. Most all other conditions it spools up slower and the ecu has no problem catching it, like in the charts above.
I have considered locking the wastegates closed as a test, but considering how fast it can spool up if conditions are right, I'm worried I'd break my intercooler or intake. I can't rely on data because it comes through too slow. I'd install a blow off valve but all the bolt-ons ones are just stupid expensive. I may install a small simple one somewhere, but I hate to drill holes in my parts, especially if it'll be visible and that's the only place there's the room to do it.
Mileage is at or above claimed. Fuel trims were good. I don't think it anticipates fuel, but maybe the O2's are too slow to read a short blip of enrichment. Either way, no indication the mix is wrong that I've seen.
It actually dropped down to 4psi several days ago, but it was the check valve on the vacuum pump, which fell apart. Imo vacuum was simply too low and the exhaust pressure simply overpowered the wastegates. Once I had the check valve out and in hand, I can't see how it didn't fall apart when the engine was first started. So I fixed that and I'm back to 8psi again. I say 8psi but the avg is less. Hard to say what avg is because the data flows so slow I'm just getting little snapshots. Like trying to watch an action movie but at only one frame per second.
Meanwhile I ordered a KESS unit that is supposed to be able to clone my ecu to a used one I have. I'm the edge of my seat waiting for it to arrive, but eta is ~15 Feb. Not sure if it can actually clone it, or if a cloned ecu will fix the problem, but it's the only thing I can think of to try. If that fails I'll have to make my own circuit to control psi.
Thanks for the reply

WRC-LVR

Maximum boost ( factory ) is 12.9 psig on this engine ( =27psia ) PSIA = PSIG +14 so you are getting 27 psia You indicate that on some runs you are getting up to 17-18 psi???? Is this in PSIA ? . IF PSIA then you are hitting 32 psig Not sure what to tell you as you are saying the car seems very slow yet it is above maximum OEM boost ??? . Please confirm that it is now back on the OEM tune and ignition /fuel are doing what they are supposed to do. LTFT STFT are correct?

Something def is not right here .............Is the car upshifting very quickly well before redline when you do a pull 0-60?. If so, then maybe a tranny control issue

If you have a dyno shop near by, roll it on and then do several pulls. Log rpm, gear position, boost and mph That should settle what your car is making
If not, then well after midnight with no cars on road, run a 0-60 time using manual shift just before redline in each gear and record it w Torque along with boost ,gear position and mph. Compare it against what MB said it can do. ( 0-60 = 4.9 seconds ) At least you'll have proof it is slow then

I looked deeper at the logs you posted. Your hp on the middle graph is ~ 280 @ wheels. Stock HP is ~380 @ crank. Using the 15 - 20 % typical driveline loss that translates to 304 or s at the wheels. So you seem to be losing ~ 20 -30 whp. at most if that log was WOT to redline

Chevota

17 psig per the app, but I don't think the car compares it to ambient so it should shoot for xx psia regardless of ambient. My ambient is between sea level and 14.4psi. Anyway, that 17 is for a very brief moment, maybe 250ms which exists only because it takes that long to open the wastegates. Plus I have to do it just right to get that #, otherwise it's like you see in the graph. The point was it's a clue that shows the turbos work and there are no leaks, otherwise that can't happen. And 17 was with the tune. Without the tune it opens the wastegates too quickly and a high peak is <10, which again was for a small fraction of a second, then back to <8.
Oem or tuned, all vitals look perfectly fine except boost. Tuned boost is supposed to be 18, but I get 12. More like 11 or less if you average it, but I call it 12.
Basically, picture someone going in while you were asleep and programming your boost to be 5 psi low, tune or not. This is, imo, exactly the problem except nobody did it, it just happened. Glitch, soft limp mode, who knows. So everything is fine, except that one very important thing.

All shifts are at ~6000 if floored. 0-60 has been as low as 5 sec with the tune on a cold 5am morning. Not sure what it is without, but no doubt >6. 0-60 runs are not easy due to traffic so I never bothered to check oem.
The tranny seems to be working as it's supposed to. I have shifted early to see if it helps, but only when it ran correctly. Considering the low-mid torque peak is gone, there is no point now.
The boost shows on Xentry, but unless Xentry holds the MB mechs hand and tells them what the problem is, they can't help. They did not check boost psi when they had it, but I did tell them what is was.

People that have dyno'd these cars claim the advertised power is very conservative and actual is more like 440. I don't know and unfortunately this problem appeared before I used an app. Also, I don't what it weighs so I just plugged in a #. I think I used 4400 to account for me in it. I'm ok with an estimate, it's more about looking for changes. Plus the numbers are not accurate anyway, the Tq and HP don't add up, which I noticed first thing. Since the HP & Tq doesn't slow the data down, I leave it in, otherwise I'd remove it. I can assure you I don't need an app to tell me if it's low because when it worked right the difference was day and night. Before this I had an E350 and I believe the 350 would take it. With the tune removed the 350 would kill it. The 550 is heavier and has less power, simple as that.
Fyi the power doesn't follow boost in a linear fashion, it seems each psi nets more power than the last psi. For example, 0 psi and 4 psi I can't even tell the difference and have to use the app to tell me which it is. 4-8 I can tell, but it's not much. 8-12 is obvious. The oem boost to tuned, which is apparently 13 to 18, is far beyond obvious and could be considered violent. It's a bigger difference than 0-12 is.