Yes should be coincidence. I posted that mine also came on and I added a quart - message went away. It was just a quart low. With more oil on the cylinders, if your oil wiper is crudded up, that could conceivably increase oil consumption, but constantly washing everything with oil is probably a good idea. So just keep running it. If it is not actually using oil though, then you just have a sensor issue and again, is unrelated.

 

This style pump is used in transmissions, and in those applications they make a few hundred PSI.

 

Not sure what you are implying.

 

Tassos suggested/implied that running the pump w/o the solenoid may expose the oil to more shearing that as design; therefore, the oil would not last the 10K miles suggested by MB. I think that is incorrect since the maximum pressure would likely be either wrist pin, or crankshaft bearings.

Since you are familiar with hydraulic pump, you can comment on the usual weak points of variable displacement rotary vane pumps. I understand they are sensitive to debris, dirty oil since it increase clearances. Working continually between 2 and 4 bar should not be an issue, correct?

 

Just to play devil's advocate here, not all vane pumps are constructed the same, different tolerances, volumes, materials, thicknesses, etc.

Again, my personal opinion is that the M157/278 pump is probably fine and not susceptible to any significant excess strain from running in normal pressure with cold oil.

 

You know the oil level sensor may be telling stories to the ECU or breached through superheat has elected sensor to become an "oil-in-harness" provider. Perhaps we should wonder how trustworthy the seasoned sensor is now: "pass/fail/marginal" ?

I can't speak much to that sensor... I have the old fashioned engine dipstick. It hasn't failed me.
If the oil sensor is turned into a service item.... you may be over filling the crankcase due to sick sensor. Do an oil drain while reading sensor data...

PlanB: mo' scientific experiment
if indeed you car is burning oil, you may want to try to deal with that condition ASAP so you can resume unplugged mod testing with proper oiling pressure.
Seafoam comes to mind... dono... if you wash clean the dry cylinders that may directly hurt the engine longevity more than help it.

Study your topic carefully - Any action may be double-edged destruction the way the original game was scripted.

 

I had this happens as well on my M278. I did not plug connector back into solenoid.

 

Yeah, the oil level reads fine on the dipstick, closer to max actually after the last 1/2qt fillup. And shows around the same level each time the warning popped up, so it's not burning oil.
Oil sensor is new since it was faulty and I just had it replaced not too long ago and it was all good again. Harness is dry and no signs of oil ingress or anything of that sort.

That's the weird thing though is that my oil level is the same via the dipstick so it's not consuming any oil. Like stated above, the sensor is new and has not given me any issues prior to this. Even with the additional half quart, it popped up twice again even though oil level is fine. I'm going on vacation soon so won't have time to experiment too much, but will unplug it once I get back and see how she does.

 

I agree with that. It should have no bearing(no pun intended) on shear. The pump is just moving more volume and honestly we are not talking much pressure at all.

vane pumps are pretty efficient and reliable pumps, they can work at much higher pressures and RPM than a gear pump, but in this scenario it’s not really relevant as we are talking very little pressure for the design.

This pump cam ring is steel and the vanes are steal, so reliably should be pretty high. The end plates are anodized aluminum just like any gear pump or small vane pump in say a hydraulic system making 200+ bar. We are only talking the difference in viscosity of a 15 weight hydraulic oil and motor oil which is almost the same anyways.

In this setup I would have no worries about running the pump in high volume constantly. It should have no reliability concerns in regards to the pump or any kind of extra stress. It’s designed to work at max volume, so it can run at max volume. The pressure is dependant on RPM, so that’s fine anyways. (It will rise with rpm as the pump is moving more against its restriction, in this case the restriction is the oil galleys and ports that distribute the oil in the engine) The highest strain pump sees is high rpm hard driving in which this system is out of play anyways. So unplugging it at low Demand situations shouldn’t do anything damaging. And when I say shouldn’t, I mean that’s the most unlikely possibility given the design of the system.

I really don’t think the info on the 2 / 4 bar is a constant. I do think that’s marketing Mumbo jumbo, I think as I mentioned above a calculated estimate for x volume against y restriction.
I don’t see any pressure regulating valves in the setup, so those two constants cannot be possible.

 

If what I gathered is correct your particular oil level sensing circuit needs work. Not related to pump solenoid topic.

This being non related go ahead and open a thread where we'll guide you to a solution for a reliable Daimler product.
We understand a new sensor was not the fix and same original issue as stayed around despite excellent service... check the nearby poor GND - Where... read VIN schematic to pinpoint

Without further splitting hair... you can simply begin fixing your poor ECU GND originated from engine bay to footwell: 90% chance of relief - Read schematic now or later, your choice .
Joy with zero part✌️

+++ If we get to the root of your liar OIL SENSOR we might help everyone else's TEMP SENSOR on the bank2 - We never know what gem will find... ECU peripheral inputs are high up on VIP list.


+++ FYI... DO YOU???
This begs the question who has an OIL LEVEL SENSOR in the pan : pay attention to this !

 

It's definitely not a constant (though I see how this could be confusing for some) but my interpretation is that given a set condition (RPM, oil temp), the solenoid valve closed (not activated) yields 58 psi. Then when activated, pressure drops to half, or 29 psi. I don't know what those conditions are, but I would assume it's probably the highest RPM where the solenoid can be energized (so, 3500 rpm?). The on/off variance is different in different conditions. At very low RPM for example, it makes a very small difference. Although, everyone has pointed to changes in low RPM operation so it must still be different. Even a few additional psi could have a positive effect on everything if it happened to be just below a threshold for efficient VVT operation, or, just below the ~20 psi for piston squirter operation. In those cases, you wouldn't need a doubling of pressure to get a benefit. And I think this is exactly what's happening.

 

What I observed when I hooked up an oil pressure gauge the other day is that at idle (600 RPM), the pressure was at 20 psi, well below the 2 bar/29 psi limit when activating the solenoid. In my case, the solenoid was already disconnected. The engine was at normal operating temperature, so that may have made a difference. However at around 1500 RPM, the pressure climbed to around 45 psi (~3 bar) and held until around 4000 RPM where it settled at 47 psi. The pressure seemed to increase linearly with the RPM.

All of that kinda pokes holes in Tasos' claim that disconnecting the solenoid puts extra stress on the pump because on startup and at idle, the pressure doesn't come close to the 2 bar limit.

 

If this hasn’t already been pointed out, see the following regarding VVT solenoid operation:

https://www.spectrapremium.com/en/af...iming-solenoid

The performance improvement we’re seeing has to do with the increased pressure at the cams outside of the intended/designed performance characteristics of the engines.

For those with the capability, it may be a smart idea to monitor for knock or misfire via data logging (either live or with the capture of Mode $06 data). So far I have not seen any issues (an occasional hit of 1 or 2 scattered misfires in a drive cycle), but for those that are tuned, you may want to do some deeper data collection to make sure nothing is going outside of tolerance on the low rpm range.

Oil squirters - poor choice by MB to limit piston oiling until such a high minimum pressure is reached. Oiling should be happening as soon as pressure builds.

It’s somewhat comforting to know that MB (mostly) sees this as an issue to ignore. Or do they now?

If I’m completely off on this, let me know and I’ll strikethrough irrelevant items in my post.

Thanks - TZ.

 

The concern is easy to debunk. I think kenneyd brought it up early as a question. The solenoids are PWM controlled and the control is designed to target a specific cam timing (they aren't just on or off). The PWM would simply adjust to whatever pulse width is needed to achieve the targeted cam timing. So from a control perspective I can't see an issue. I'd invite a pre- and post-unplugging person to log cam timing and attempt to show a difference, and specifically to show if cam timing goes from "proper" to "improper." I think the opposite is true. I think the low oil pressure makes the phaser struggle to do its job, but never set a code. Based on the butt dyno, the problem before isn't just that they can't achieve proper timing, it's that it ends up oscillating trying to reach the target. With adequate oil pressure, the phasers achieve desired timing without oscillation.

Perhaps more importantly, during high load conditions, the oil pump solenoid is deactivated providing full oil pressure. So the phaser control has already seen the max oil pressure this engine is capable of. During all conditions where the oil pump solenoid would be active there is LESS pressure than during high load, full RPM situations.

Not a concern at all, for me.

 

WHY is this Oil Pump Solenoid so amazing for our engine power ?

Let's go see where the elusive Easter-egg got concealed inside this complex enchilada.


Concidering our V engines, there are 4x overhead camshaft phasers dynamically positioned by the ECU. This gets accomplished by individual PWM solenoids located on the face of VVT covers. These solenoids control the position of the phaser gear under the watchful eye of the CPS Hall sensor.

Based on desired camshaft timing, the ECU sends more or less pressure using the duty cycle of the VVT solenoids.

Perfect, everything is exactly controlled by a computed ECU map. This adjust the valves timing overlap, not the duration or height opening. It helps breath better at lower RPM for greater torque.


> WHAT'S WRONG THEN?
The camshaft positioning system goal is to smooth variables out of the timing work for it to become exactly predictable. The ECU tries to position the cams where it wants them ahead or behind of a neutral resting lock position. Each camshaft is independently managed to iron out differences.

Differences MB made sure to have plenty. Many variables keep changing non-stop: the engine RPM, the available oil pressure, the target position, the antagonistic efforts, the chain slack... Regardless ECU wants Cams positioned on time!

It uses a map to quickly work out the best PWM duty for its camshaft solenoids.

> Variable Pump pressure:
All engines oil pump pressure vary based on RPM between min to max.
Our adjustable pump does the same plus has an extra factor of adjustment. It has two separate max values. The min pressure are essentially the same.

I wrote about the dual pressure slopes here - (MBW link)

Practically the output pressure rises on a linear slope towards the max value that is based on ECU pump solenoid. It's operates with PEM but with only two high/low values, so really an ON/OFF solenoid.
Lets skip over what solenoid does to the pump. It counteract a reset spring to lower the volume of the compression chamber. It is not used to dump out pressure of a fixed pump. Our available volume physically varied to manage two pressure slopes towards max pressure.


> ANTAGONISTIC FORCES.
Now let's see what plays against this wonderful computer system: comes the mighty HPFP!!

That is were the reality of things gets complicated and engine performance fails expectations.

Inside the VVT gears we have oil and air controlled by a valve.
That VVT gear chambers pretty much works like an elastic shock absorber. It soften the camshaft efforts that are applied against the chain slack.
Negative counter energy is cushioned so it doesn't affect the weak soft tensioner system. I can see this helping to save energy by reducing frictions.

Ground zero for troubles is Bank1 Intake camshaft. It has the most work to do unlike the other 3 shafts that simply work valve springs.

In pure Mercedes fashion the HPFP come with multiple flavors. Triple or quad cams, single or dual pumps each with a timed proportioning valve that runs synchronously with lobes.

The efforts are tremendous as the cam lobes are ultra stip 90° angles, the return springs are strong, the plunger shaft are dried... so the dry roller needle bearings develop a flat spot when they quit rolling.

On one end we have a smooth VVT drive system on the other the jerking 8x lobes poking on/off: the rattlesnake!
These HPFP forced require adequate oil pressure to counter them. When gears are limp they have an automatic lock pin that prevents wild jerking (the "startup rattle" when pins are spent).


> HPFP TIMED SYSTEMS: rattlesnake vs. quiet
These extreme pressure pumps work with a plunger piston shaft and an open/close valve.

It's driven by 3 or 4 lobes per cam revolution spining at half crank speed.
So at 1KRPM is a 500x4 = 2k strokes per minutes
33 pops per second x2 pumps.

The computer has to time the opening and closing of the proportioning valve to best build the target pressure measured by rail sensor.

The ECU uses best-efforts to quickly close in target values until a perfectly controlled timed valve regulation can begin to take place. Precise regulation loop takes serious math to control closing on the target value. That's what VVT positioning delivers for HPFP controlled timing.


When that happens you are graced with amazing "Start no-crank" and rattlesnake-free quiet injection. The engine power output becomes unbelievable from 900.RPM because everything is perfectly tuned.
Even the tranny has no other option but to excel with great predictability.
The ECU is super happy to put out fuel to make the chassis fly effortlessly. That's why we purchased the finest Daimler engineered product, right?

The resulting heat is well managed continuously from the oil squirters to heat exchanger, to smart T-stat, to PWM fan: Coooled within favorable limits. No more heat spikes or killer soaks.

Now the whole system really shines. Either smooth or violent power on tap!
Thank Mercedes for this exciting quest game.


> TAKE HOME:
+ Good oil viscosity at regulated temps
+ Good timing maps adaptations
+ Good tensioners, VVT Gear pins
+ Good linear oil pressure
= REALLY GOOD OWNERSHIP!!

 

Its not proportionally variable for this pump, its two stages, so the benefit people are seeing at the low RPM is more oil volume. think of this pump as high and low volume settings. the pressure increase seen in the low RPM is due to the increase in volume being added to the system.

 

Yes high and low, but the amount low vs high is proportional to rpm. My comment is focused on the WIS information that talks about 4 bar vs 2 bar which is erroneous.

 

https://mbworld.org/forums/e-class-w...ml#post8621276
Here is the pump behavior with and w/o the valve. It seems proportional from idle to relief pressure

 

Question, how do I know if my car has the solenoid? It's a 2013 E550. Sorry if this is a dumb question I just can't find a solid answer.

 

90% chance yes... M278, right?

Does it have a mushy accelerator around 1000.RPM and the weird confused tranny response??

 

That looks like the max pressure is regulated the way it responded. I mean it was already obvious the way it stopped going up with RPM, but also the way it seemed to correct itself back to the target max pressure really looks like regulation to me. I assume it's part of the mechanical relief system.

Does it make more pressure at cold start?

 

I will check, but probably later this week. I'm in the middle of a "honey do" project at the moment.

 

- 20 miles
- no MIL
- better low rpm response

Will report findings as mileage accrues.

 

Exactly

 

Does the m278 and m157 have an OIL TEMP sensor/sender?

I ask this because I saw a thread the other day about amg menu in the m276 v6's (NA and Biturbo) and someone stated with mercedes benz literature proof that those dont even have an oil temp sensor and MB is just using software equations based on engine values like load and running time to calculate a value. I have amg menu on my wifes 14 e350.

I ask because I just put AMG menu on my s550 and would be good to know if what im seeing is actual oil temp or something calculated by the car itself.