Hi guys,

I am experiencing a performance issue with my 2015 E400 that has 118.000 km. I have brought the cars to multiple mechanics here in Canada that were not able to determine what the issue is. I just did a pull (full load) and will post those values at the bottom of my post. I will also upload the file.

What is noticeable as well on the car is the waste gate rattle and a noticeable difference between two exhausts. The passenger side seems much louder and a lot more air is coming out. The last mechanic I brought the car to told me that the drivers side exhaust is "too cold".

What I have done so far is:

1. Checked for any stored of current fault codes with xentry
2. Changing the boost solenoid
3. Checked for vacuum leaks from the brake booster to the waste gate solenoids
4. Replaced the check valve at the vacuum pump
5. Replaced the spark plugs
6. Connected a smoke machine to both exhaust tips
7. Connected a smoke machine to the air filter box
8. Compression test with Xentry

This is really as far as my knowledge goes and without great help from mechanics it is frustrating that I am not able to fully enjoy my car. Please help me with letting me know where I should start. Many thanks in advance

Calculated load value (%) 99.60784
Short term fuel % trim - Bank 1 (%) -3.90625
Long term fuel % trim - Bank 1 (%) -0.78125
Short term fuel % trim - Bank 2 (%) -3.125
Long term fuel % trim - Bank 2 (%) -0.78125
Intake manifold absolute pressure (kPa) 153
Engine RPM (RPM) 5883.5
Absolute throttle position (%) 47.843136
O2 voltage (Bank 1 Sensor 2) (V) 0.89
O2 voltage (Bank 2 Sensor 2) (V) 0.885
Fuel rail pressure (kPa) 15100
Commanded evaporative purge (%) 99.60784
Fuel level input (%) 45.098038
Evap system vapor pressure (Pa) -537.25
O2 sensor lambda wide range (current probe) (Bank 1 Sensor 1) 0.925675
O2 sensor current wide range (Bank 1 Sensor 1) (mA) -0.3046875
O2 sensor lambda wide range (current probe) (Bank 2 Sensor 1) 0.924211
O2 sensor current wide range (Bank 2 Sensor 1) (mA) -0.30859375
Fuel/Air commanded equivalence ratio 0.931592
Relative throttle position (%) 73.333336
Fuel rate (l/hr) 23.410854
Mass air flow rate (g/s) 70.32947
Boost (kPa) 53
Engine Power (PS) 213.05362
Engine Torque (N•m) 257.43558
A/F Commanded 13.638507

 

• So, you have no DTCs?
• What exactly is your "performance issue"?
• What does the mechanic mean by "too cold"?
• What other feedback have you gotten from shops you've gone to?
• Does your exhaust have a cross-over pipe? (See pic)

118,000 km is not that many miles. However, you should have had your transmission serviced by now. If your driver's side cat was clogged, I'm sure you would get a code.

 

• I do not have any DTC's
• My performance issue is that the car feels sluggish, especially in the lower end. According to the OBD2 values it never seems to deliver more than 300nm of torque vs the 480nm it should have.
• My mechanic said that in his opinion after measuring the temperature of my exhaust with an infrared thermometer, the temperature was too low. He thought this indicated an engine / compression issue on that bank.
• The feedback from most mechanics is that I should start with a carbon cleaning based off the mileage. How ever, this seems unlikely to be the issue as only one bank is affected.
• I forgot to mention that I had a transmission service done when I bought the car at the dealership.
• I do not have a cross-over pipe, I will upload a screenshot of the bottom of the car if that helps
  

Thank you for your help!

 

How long have you had the car? Is the sluggishness new?

You mentioned more exhaust gas from the passenger side, correct? That tells me there may be some type of blockage, maybe in the driver's side cat.

Where did the mechanic measure the temperature? Before or after the cat?

And you did a relative compression test. Was there any significant differences between cylinders?

I agree with you that if you had carbon buildup, it would be on both banks. Also, did the mechanics give you a price to do a carbon cleaning?

I also noticed that the plastic cover over the driver's side lower control arm in the rear is missing. That's why it looks rusted.

 

I have had the car for about 2 years now. The sluggishness is not new, it has been there since I have it. I have been trying to diagnose this issue almost since the beginning.

Yes, there is much more exhaust gas (and noise) from the passenger side exhaust. I was thinking the same about the blockage, by the mechanic told me he the drivers side exhaust, including the cat was much cooler. This would mean that the cat isn't blocked. He also said the same as you that if there was a blockage, there would have been a check engine light.

Xentry said there was a difference of 11 rpm detected during the compression test, I will upload a screenshot.

The price he gave me for the carbon cleaning would come down to about 725 USD.

Thanks for noticing the plastic cover, I will ask to have it installed the next time the car goes in for service.

 

The plastic cover is somewhat protective, but cosmetic as well. I would check the price first. You could also just clean off the rust and spray undercoating on it.

Cats are supposed to be HOT. That's why on cold startup the secondary air injection runs for a few moments to quickly heat up the cat by injecting additional air (o2) into the exhaust stream. If the cat is cold, that means something is not right. But, if it were blocked, I would expect the increased back-pressure on that bank to have slower compression numbers. We do see the compression speed of cylinders 4, 5, and 6 being slower than 1, 2, and 3, but not significantly. But, are they slower enough to indicate a problem?

If the car has always been like this, maybe it's just normal. I would not trust OBD settings for your calculated torque. I think a dynamometer is best for that. Still, advertised max torque is ~480Nm (354 ft-lb).

Options available are to get an ECU tune. I have a @VividRacing tune that bumps the hp from 329hp to approximately 400hp. You can do this at home with a hand-held flash tool. You can also have the transmission configured to enable Agility/Sport+. I used BenzNinja for that. He also tweaks the throttle to be more responsive. Since you already have the equipment to run XENTRY, you would not need another computer.

Adding to that, there are a couple of "mods" you can also do at home for free: Oil Pump Solenoid Disconnect and Alternator LIN bus disconnect. (I have linked the discussions instead of trying to explain the details here.)

The Oil Pump Solenoid disconnect disables the oil pump from keeping the oil pressure artificially low, allowing linear increases in oil pressure to the benefit of better lubrication. The LIN BUS disconnect stabilize the voltage for more predictable electronics.

 

Here is a recent link about BenzNinja services.

https://mbworld.org/forums/s-class-w...-ireviewn.html

 

I don't know what is the expected boost level of a stock E400 (I can make a log on mine latter on this week) but your is maxing out at 53 kPa (0,53 bar or 7,7 psi) which seems low. I would expect an stock engine to use something in between 0,8 and 1 bar of boost. since you mentioned there is a noticeable rattle between both wastegates, it could be interesting to drop the cats and inspect the hot side of both turbochargers. Testing the pressure the wategate actuators are working can also give you some guidance in the right direction. If you have a borescope, you can inspect the cold side of the turbos by just removing the airboxes (one screw on each side).

 

@Andre Cateb brings up some good points and suggestions.

Since the car has been this way since you bought it, could the previous owner have tried to make adjustments to the wastegate controller to hold boost longer, but messed up the adjustment? Or, could it have been improperly tuned?

 

First thoughts would be the waste gate. You mention it rattles, and that needs to be checked.

next, I would do a real compression test and when the spark plugs are out, you could have them boroscope the cylinder and peek at the valves to see if they actually do need carbon cleaning. Imo, since many of your numbers are even between the two sides, it doesn’t look like your car is adjusting for an intake issue. If you are handy, purchasing the tools would be less costly than having someone else do these things for you.

Was the exhaust temp checked at the tips, or at the headers? If you are cold at the headers, you need to look at the engine, injectors, head gasket, rings…

editing one last time to say that it’s entirely possible that since this issue has been pervasive for your entire ownership of the vehicle that the previous owner dumped the vehicle because they discovered a greater problem.

 

Keep in mind those engines have a natural rattle on their wastegate. This is only significant if one side is different them the other. @JettaRed could be on to something. If the previous owner had that engine tunned and de-tunned it before selling it could be just a programing issue.

 

My wastegates are rock solid when running, absolutely no vibration. I have about 53,000 miles on my car.

The wastegates on our engines are normally open for "safety" reasons. They are vacuum actuated by the dedicated vacuum pump (unlike designs that use engine vacuum). They only close on demand and if there is sufficient vacuum to overcome the opening spring. If the vacuum pump (which has already been addressed by @Electronick ) is malfunctioning or a vacuum line has a leak, the wastegate(s) may not be fully closing, severely limiting boost. That's why I hate not having a boost gauge on the car.

I wonder if there is a way to temporarily hook up a mechanical boost gauge for diagnostic purposes (like you can with oil pressure).

 

I did a first gear pull while recording the data with the Creader Elite Scanner. I don't know how to export data from it yet but I was able to extract a print screen. The car lost a bit of traction and the TC did its thing so the acceleration curve is not the smoothest. In any case, maximin boost was at 1,643 bar and maximum intake manifold pressure maxed at 1,5 bar (which I assume was the target value).

Looking again at OP data, there's something I've noticed that while his boost maxed out at 0,5 bar his intake manifold pressure was reading 1,5 bar. It might be just a difference in absolute or relative pressure reading from the scanner. My ambient pressure was at 901 hPa (0,9bar) so my engine required a boost of about 0,6 bar to reach the target manifold pressure. But since the boost pressure sensor reads absolute pressure, it read 1,6 bar.

 

If I remember correctly, years ago when I dyno'd a car I had modified, I think the shop did 2nd or 3rd gear (manual tranny) pulls. I would also think that a 2nd or 3rd gear pull would give you better readings since boost will probably be maximized under a heavier load. 1st gear doesn't load the engine enough under normal circumstances.

For example, on my 2004 Audi TT (tuned) I hit max boost at mid-range rpm of about 21 psi momentarily when going uphill in 3rd or 4th gear. It doesn't hold that pressure for very long and drops off as speed and rpm increase. The relatively stable boost pressure across the rpm range in your graph makes me sceptical about what the numbers mean. Of course, we are dealing with a more sophisticated system on our Mercedes than the rudimentary setup on the Audi.

I would still like to see a pressure gauge reading to be sure.

 

Thanks for the ideas. I did try a Racechip which was the easiest and cheapest way for me here in Canada. How ever, it did not feel like the car was any faster which indicated to me there was something wrong as well. I will look into the Agility mode for the transmission and throttle response, thank you. I also disconnected the Oil Pump Solenoid and this made the car smoother in the low end but not faster. I will look into the Alternator LIN bus disconnect.

 

Thank you for doing the measurement! I would say that there is a small difference in boost numbers but nothing crazy. Like @JettaRed mentioned, I will try a pull in 2nd and 3rd gear and report back

 

Both my wastegates rattle under partial load. I can close both wastegates by applying about 17 PSI with the manual vacuum pump. It really sucks not having a dedicated boost gauge on the car, or in my case even per bank.

 

I'm still getting into the grips with the Creader scanner and its datalogging function. I'm going to try to find a parameter group that allows me to select boost pressure and engine output (HP/torque) however I could not find a customizable parameters group like in Xentry.

 

I do have this fluttering sound but much less bad. I hear it more while driving and accelerating under partial load. Both turbos sound exactly the same. I went to the dealer to have that fix carried out but it didn't change anything. Somehow I wonder if they actually did it because they had no clue when I showed them this document.

 

I am using the Veepeak OBDCheck Ble with an app on the phone. Works well too

 

Coils and plugs changed when?

Harness cam sensors and magnets connectors photos?

Spark plug photos?

XENTRY compression test screenshot?

Dragy run screenshot before and after “problem”?

This car is modified. All bets are off.

@Electronick What is your gut telling you?

 

I am not at home in front of my usual PC, I am in Bali.
So me can't access my datalog on my E400 engine.

===========

The E400 of W212 , the engine M276.820 at 333 HP is torque limited to 480Nm, and not boost limited per se.
I am speaking of standard engine, not tuned one.

The turbocharging algo is targeted for mid torque and not redline WOT. This engine is comfort engine and not sporty engine.
Highest turbo boost of 0.8 bar or 11.7psi or 80Kpa above ambient pressure of the location, or altitude.
If at sea level, we can get to see the boost to 11ish psi above ambient, or 1.8 BAR of Manifold Absolute Pressure.
1 ATM at sea level is very close to 1 BAR, its 1.013 BAR in fair weather sea level.
Read post #112 here : https://mbworld.org/forums/e-class-w...ml#post9068187

As I said, this is comfort turbo, the maximum boost is at 4,500ish RPM , not at 6,000 ish RPM.
In fact at high gear, at low 3,000 ish RPM there could be high boost too.

Electronick, what is your location altitude ?
You can verify what your ECM is seeing by not running engine, but Ignition ON and using entry.
There will be 4 pressure sensors value you will get.
01 - The built in ambient pressure sensor inside the ECM MED17.7. See black color value at 993.0 hPa
02 - The Intake Manifold Absolute Pressure sensor at the front of the intake manifold
03 and 04 - The air filter box pressure sensors, one each side.





To Note :
AA. Your high pressure fuel sensors value is good. Its operation profile is the same as mine

When idiling, 120ish BAR or 120,000 Kpa is normal, no 1 in red. Highest 190BAR at above idling RPM but throttle being light is normal, no 3 in blue.
Kickdown for higher RPM, 150 BAR is normal, No 2 in green.


BB. How good is your wastegate flap condition ( air tightness ) to keep boost, no one will know until visual inspection is done.

CC. Your lambda sensors the front ones seems good, in terms of its operation.

================

Test your low fuel pressure values while doing 1st and 2nd gear WOT.
Make sure you have enough fuel volume into the high pressure pump.
Read here , post #12 : https://mbworld.org/forums/e-class-w...ml#post8568085

Fast summary



Let us know the result.....

 

I changed only the plugs, about 5000km ago. I did not change the coils. The cam sensors and front valve covers do have a leak a tiny bit of oil and I intended on having this fixed after I find out the issue I am experiencing. I do not have any dragy screenshots before the issue because I have the issue since I have the car. I only used the Racechip for about 2 weeks, since I wanted to see if I could amplify the issue and hopefully get a code. When this didn't happen I removed the racechip.

 

Thank you for this info @S-Prihadi I agree that this is a comfort turbo and I do drive my car in a relaxed fashion (unlike you haha). From the boost figures and from what I experience, it seems like there is boost but it just takes some time before it's there. I just connected a vacuum pump to the boost solenoid (on the turbo end) and the pressure was about 27 inHg / 13,2 PSI. I can fully close the wastegates with the vacuum gauge with 17 inHg / 8,3PSI so this seems like a little overkill. When I actuate the wastegates with xentry I am not sure if they close fast enough. I will upload a video, let me know if you prefer that I upload it to Youtube.

I am pretty close to sea level here in Montreal, I uploaded a screenshot of the xentry pressure values.

Last week my laptop battery died and I can only use xentry while stationary. When I will have this fixed, I will check for the fuel pump voltage. I might as well just change the filter.

For me the most likely issue at this point is some sort of exhaust issue with some back pressure in combination with the waste gates operating slowly or not properly closing. But not severely enough to trigger a code. What do you think of the boost values in my test file compared to being at sea level?

 

Coils and cam sensors need to be changed. Likely also O2 sensors. If it was my car I would replace these three items. It's an old car, it's time.