Fuel rail pressure and pump concern
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 52
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From: Lille, France
2009 E350 CDI Bluefficiency 4matic
it was indeed. Thank you for your input earlier about the fuel type. Now I can definitely tell when it is gas and when diesel by the smell. It was a long 2 months event. I replaced the oil cooler gaskets as well while waiting for parts. I learned a lot of things while taking this engine apart.I think I will go ahead and change the HP O-rings in the next weeks. Geniushanbiao has sent a file with the timing of the HP, but now the question is, how do you set the1st cylinder to the upper point w/o opening anything?
This forum is very helpful!! Thank you all for the information provided!
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R320, Astro, JSW, ST4
From earlier discussion it was later model OM642 needed to worry about pump drive orientation/timing, right?
Are you sure you need to time it? 2009 is before the bigger changes to this motor, if I'm not mistaken.
If you do need to "time" the HP pump, are there any scan codes which indicate the harmony resonance problem? I don't know, my car is older.
Or, is there any way of testing whether you have issue with motor running, before taking it apart again?
Either pump timing correct, or you need to rotate pump 180 degrees while it is off. You don't really need to know top dead center.
Are you sure you need to time it? 2009 is before the bigger changes to this motor, if I'm not mistaken.
If you do need to "time" the HP pump, are there any scan codes which indicate the harmony resonance problem? I don't know, my car is older.
Or, is there any way of testing whether you have issue with motor running, before taking it apart again?
Either pump timing correct, or you need to rotate pump 180 degrees while it is off. You don't really need to know top dead center.
Last edited by B34chBum; May 19, 2020 at 01:27 PM. Reason: clarification
Senior Member
Joined: Apr 2012
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2012 ML350 Bluetec, 2015 GL350 Bluetec
From earlier discussion it was later model OM642 needed to worry about pump drive orientation/timing, right?
Are you sure you need to time it? 2009 is before the bigger changes to this motor, if I'm not mistaken.
If you do need to "time" the HP pump, are there any scan codes which indicate the harmony resonance problem? I don't know, my car is older.
Or, is there any way of testing whether you have issue with motor running, before taking it apart again?
Either pump timing correct, or you need to rotate pump 180 degrees while it is off. You don't really need to know top dead center.
Are you sure you need to time it? 2009 is before the bigger changes to this motor, if I'm not mistaken.
If you do need to "time" the HP pump, are there any scan codes which indicate the harmony resonance problem? I don't know, my car is older.
Or, is there any way of testing whether you have issue with motor running, before taking it apart again?
Either pump timing correct, or you need to rotate pump 180 degrees while it is off. You don't really need to know top dead center.
From the WIS I have it's the EARLY model OM642 that need to worry about pump drive orientation. My 2012 and 2015 don't need timing for installation according to WIS.
But OP's pump needs to be properly timed I checked his VIN on my WIS.
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Joined: Mar 2017
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R320, Astro, JSW, ST4
Thanks geniushanbiao very much for correction, I got in hurry responding.
So, how to test if the resonance issue is present before taking pump off again?
At what RPM range(s) does it occur?
Is it audible range frequency (something detectable by phone mic / app)?
I'm recalling how you can see whether the key fob infrared is working by pressing the button and taking a picture of end of fob with your phone...
Wonder if there is a 'street' test way of determining - I hate fixing things that aren't broken - because the timing of pump may actually be correct as it is.
Vaseto, searching forum I only see finding TDC on OM642 in reference to timing chain service, where the right-hand valve cover comes off and marks are on cam assemblies.
There is a TDC mark on the crank pully - you can pull the glow plug on #1 and feel for compression (outward air pressure) at the glow plug hole, as the mark approaches TDC.
You need a 2' long breaker and 22mm(?) socket to turn the motor, and probably an assistant to feel for the upstroke of the cylinder.
So, how to test if the resonance issue is present before taking pump off again?
At what RPM range(s) does it occur?
Is it audible range frequency (something detectable by phone mic / app)?
I'm recalling how you can see whether the key fob infrared is working by pressing the button and taking a picture of end of fob with your phone...
Wonder if there is a 'street' test way of determining - I hate fixing things that aren't broken - because the timing of pump may actually be correct as it is.
Vaseto, searching forum I only see finding TDC on OM642 in reference to timing chain service, where the right-hand valve cover comes off and marks are on cam assemblies.
There is a TDC mark on the crank pully - you can pull the glow plug on #1 and feel for compression (outward air pressure) at the glow plug hole, as the mark approaches TDC.
You need a 2' long breaker and 22mm(?) socket to turn the motor, and probably an assistant to feel for the upstroke of the cylinder.
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 52
Likes: 1
From: Lille, France
2009 E350 CDI Bluefficiency 4matic
It seems both sensors are shot. KOEO Intake pressure shows 325 hPa, Boost sensor shows 2525. Exhaust sensors show 330. I believe both pressure sensors are done, I am not sure if the other one is bad too, waiting to put new sensors and check again.
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 52
Likes: 1
From: Lille, France
2009 E350 CDI Bluefficiency 4matic
Thanks geniushanbiao very much for correction, I got in hurry responding.
So, how to test if the resonance issue is present before taking pump off again?
At what RPM range(s) does it occur?
Is it audible range frequency (something detectable by phone mic / app)?
I'm recalling how you can see whether the key fob infrared is working by pressing the button and taking a picture of end of fob with your phone...
Wonder if there is a 'street' test way of determining - I hate fixing things that aren't broken - because the timing of pump may actually be correct as it is.
Vaseto, searching forum I only see finding TDC on OM642 in reference to timing chain service, where the right-hand valve cover comes off and marks are on cam assemblies.
There is a TDC mark on the crank pully - you can pull the glow plug on #1 and feel for compression (outward air pressure) at the glow plug hole, as the mark approaches TDC.
You need a 2' long breaker and 22mm(?) socket to turn the motor, and probably an assistant to feel for the upstroke of the cylinder.
So, how to test if the resonance issue is present before taking pump off again?
At what RPM range(s) does it occur?
Is it audible range frequency (something detectable by phone mic / app)?
I'm recalling how you can see whether the key fob infrared is working by pressing the button and taking a picture of end of fob with your phone...
Wonder if there is a 'street' test way of determining - I hate fixing things that aren't broken - because the timing of pump may actually be correct as it is.
Vaseto, searching forum I only see finding TDC on OM642 in reference to timing chain service, where the right-hand valve cover comes off and marks are on cam assemblies.
There is a TDC mark on the crank pully - you can pull the glow plug on #1 and feel for compression (outward air pressure) at the glow plug hole, as the mark approaches TDC.
You need a 2' long breaker and 22mm(?) socket to turn the motor, and probably an assistant to feel for the upstroke of the cylinder.
Senior Member
Joined: Apr 2012
Posts: 356
Likes: 66
2012 ML350 Bluetec, 2015 GL350 Bluetec
Thanks geniushanbiao very much for correction, I got in hurry responding.
So, how to test if the resonance issue is present before taking pump off again?
At what RPM range(s) does it occur?
Is it audible range frequency (something detectable by phone mic / app)?
I'm recalling how you can see whether the key fob infrared is working by pressing the button and taking a picture of end of fob with your phone...
Wonder if there is a 'street' test way of determining - I hate fixing things that aren't broken - because the timing of pump may actually be correct as it is.
Vaseto, searching forum I only see finding TDC on OM642 in reference to timing chain service, where the right-hand valve cover comes off and marks are on cam assemblies.
There is a TDC mark on the crank pully - you can pull the glow plug on #1 and feel for compression (outward air pressure) at the glow plug hole, as the mark approaches TDC.
You need a 2' long breaker and 22mm(?) socket to turn the motor, and probably an assistant to feel for the upstroke of the cylinder.
So, how to test if the resonance issue is present before taking pump off again?
At what RPM range(s) does it occur?
Is it audible range frequency (something detectable by phone mic / app)?
I'm recalling how you can see whether the key fob infrared is working by pressing the button and taking a picture of end of fob with your phone...
Wonder if there is a 'street' test way of determining - I hate fixing things that aren't broken - because the timing of pump may actually be correct as it is.
Vaseto, searching forum I only see finding TDC on OM642 in reference to timing chain service, where the right-hand valve cover comes off and marks are on cam assemblies.
There is a TDC mark on the crank pully - you can pull the glow plug on #1 and feel for compression (outward air pressure) at the glow plug hole, as the mark approaches TDC.
You need a 2' long breaker and 22mm(?) socket to turn the motor, and probably an assistant to feel for the upstroke of the cylinder.
I remember the crank pulley bolt was a 24mm but I can be wrong. I turned the engine when I was replacing transmission fluid to find the TC drain plug. Reversible rachet works much better than breaker bar so you don't need to change position frequently. I have an extendable one I bought in 2009 and still using it today. With less than $30 you can't beat it.
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2012 ML350 Bluetec, 2015 GL350 Bluetec
Theoretically there's a way to tell the cam position by monitoring the cam position sensor while you turn the engine. I never tried it so not sure if it works but it's worth a simple try. Just disable the fuel pump, hook up your diagnostic tool and turn the engine by hand.
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Thread Starter
Junior Member
Joined: Apr 2020
Posts: 52
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From: Lille, France
2009 E350 CDI Bluefficiency 4matic
I don't think there are ways to determine TDC without taking off something. There are various ways to do it just which one goes easier. I guess removing the glow plug is probably the easiest way to do just a little risky from damaging the glow plug though. The trick is that you can use a rubber plug to plug the glow plug hole and turn the engine slowly. When the plug is pushed out you know it's doing compression. I got a nice set of rubber plugs from ebay it's pretty handy when doing my oil cooler seals.
I remember the crank pulley bolt was a 24mm but I can be wrong. I turned the engine when I was replacing transmission fluid to find the TC drain plug. Reversible rachet works much better than breaker bar so you don't need to change position frequently. I have an extendable one I bought in 2009 and still using it today. With less than $30 you can't beat it.
https://www.amazon.com/T29771-2-Inch...9986085&sr=8-5
I remember the crank pulley bolt was a 24mm but I can be wrong. I turned the engine when I was replacing transmission fluid to find the TC drain plug. Reversible rachet works much better than breaker bar so you don't need to change position frequently. I have an extendable one I bought in 2009 and still using it today. With less than $30 you can't beat it.
https://www.amazon.com/T29771-2-Inch...9986085&sr=8-5
Thread Starter
Junior Member
Joined: Apr 2020
Posts: 52
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From: Lille, France
2009 E350 CDI Bluefficiency 4matic
Theoretically there's a way to tell the cam position by monitoring the cam position sensor while you turn the engine. I never tried it so not sure if it works but it's worth a simple try. Just disable the fuel pump, hook up your diagnostic tool and turn the engine by hand.
check this info out though: https://dogandlemon.com/articles/own...blem-diagnosis
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2012 ML350 Bluetec, 2015 GL350 Bluetec
Fun thing is that I also scraped out a lot of carbon buildups from the intake port of the cylinder head. This is especially heavy on the Cyl4. If I didn't plug the 2 front holes of the oil cooler, those carbon will easily fall into either the oil port or the coolant port.
MB has a specified plug set that they ask us to use but it's ridiculously expensive.
Thread Starter
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Joined: Apr 2020
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From: Lille, France
2009 E350 CDI Bluefficiency 4matic
The WIS calls for plugging a lot of openings when removing parts, especially those high pressure fuel lines and rails. Also after I removed the turbo pedestal and oil cooler, there are openings for oil and coolant that face up I don't want to get them contaminated when I perform a good cleaning of the area. The leaking oil cooler causes a pretty nasty surroundings full of oil based sludge and the cleaning will cause droppings into the oil and coolant system if these holes are not plugged.
Fun thing is that I also scraped out a lot of carbon buildups from the intake port of the cylinder head. This is especially heavy on the Cyl4. If I didn't plug the 2 front holes of the oil cooler, those carbon will easily fall into either the oil port or the coolant port.
MB has a specified plug set that they ask us to use but it's ridiculously expensive.
Fun thing is that I also scraped out a lot of carbon buildups from the intake port of the cylinder head. This is especially heavy on the Cyl4. If I didn't plug the 2 front holes of the oil cooler, those carbon will easily fall into either the oil port or the coolant port.
MB has a specified plug set that they ask us to use but it's ridiculously expensive.
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2012 ML350 Bluetec, 2015 GL350 Bluetec
ok. what am I supposed to see on the tool? The numbers will change when? And then when they change does that mean we have a TDC?
check this info out though: https://dogandlemon.com/articles/own...blem-diagnosis
check this info out though: https://dogandlemon.com/articles/own...blem-diagnosis
I will take a look when I hook up my Xentry next time for routine check and let you know if I find anything.
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2012 ML350 Bluetec, 2015 GL350 Bluetec
I see, you just use them to plug other holes lol. I just did the seals last month and it's true, a lot of garbage and mess. I used tape to tape the intake inlets, saw it on a video. Replaced the flaps motor and the flap driving arms with aluminum ones too. And then I realized, I could have probably used a resistor instead. Too late, at least I have all new parts now.
Thread Starter
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Joined: Apr 2020
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From: Lille, France
2009 E350 CDI Bluefficiency 4matic
Basically you look at the raw signal of the cam position and crank position sensors. They should give out square wave signals when the engine is turned (make sure your ignition is ON and fuel system disabled). This can be seen on either Xentry or an oscilloscope. I'm not sure how MB designed this but usually, when one wheel is at 0 degrees there should be a different signal (usually an empty signal slot or something) so the ECU knows the wheel is at 0 degrees. Each camshaft turn should see the crankshaft pulley hitting the 0 twice. When both sensors are giving the different signal the ECU knows the Cyl1 is at TDC compression and signals the injector of Cyl1 to fire. Then the ECU counts the number of wave peaks to determine the firing timing of the rest of the cylinders. I'm not an MB engineer so I don't know how they coded this procedure but this should be a generic way engineers do it. You can observe the pattern from the monitoring as you turn the engine and compare the crank sensor data to the timing marks you see on the pulley.
I will take a look when I hook up my Xentry next time for a routine check and let you know if I find anything.
I will take a look when I hook up my Xentry next time for a routine check and let you know if I find anything.
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2012 ML350 Bluetec, 2015 GL350 Bluetec
Thank you. Good information. Now, all I need is a Xentry system haha. My scanner does not show this. I will check for markings first. The plug on my 1st cylinder has an intermittent error for an open circuit, so maybe I can pull it off. I have no chance to get to such a way of diagnosing.
Thread Starter
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From: Lille, France
2009 E350 CDI Bluefficiency 4matic
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R320, Astro, JSW, ST4
Thanks again for the discussion - makes me wonder how practical it would be to use a multimeter to watch the V change as engine is rotated.
Hook it up to just the intake cam sensor, note the 2 voltages and watch the pattern of changes.
Might be possible to just observe the lack of change at TDC, assuming a missing square in the wave.
Either the change is there (TDC on wrong cylinder, keep turning the engine), or not (TDC on #1)
The cams move very slowly when you're hand cranking.
Hook it up to just the intake cam sensor, note the 2 voltages and watch the pattern of changes.
Might be possible to just observe the lack of change at TDC, assuming a missing square in the wave.
Either the change is there (TDC on wrong cylinder, keep turning the engine), or not (TDC on #1)
The cams move very slowly when you're hand cranking.
Thread Starter
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Joined: Apr 2020
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From: Lille, France
2009 E350 CDI Bluefficiency 4matic
geniushanbiao,
I put a new exhaust pressure sensor today and the values were the same - around 325, providing the other 2 pressure sensors are faulty. (Intake and boost). IS it possible they could be causing the exhaust pressure to be that low?
I put a new exhaust pressure sensor today and the values were the same - around 325, providing the other 2 pressure sensors are faulty. (Intake and boost). IS it possible they could be causing the exhaust pressure to be that low?
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2012 ML350 Bluetec, 2015 GL350 Bluetec
Thanks again for the discussion - makes me wonder how practical it would be to use a multimeter to watch the V change as engine is rotated.
Hook it up to just the intake cam sensor, note the 2 voltages and watch the pattern of changes.
Might be possible to just observe the lack of change at TDC, assuming a missing square in the wave.
Either the change is there (TDC on wrong cylinder, keep turning the engine), or not (TDC on #1)
The cams move very slowly when you're hand cranking.
Hook it up to just the intake cam sensor, note the 2 voltages and watch the pattern of changes.
Might be possible to just observe the lack of change at TDC, assuming a missing square in the wave.
Either the change is there (TDC on wrong cylinder, keep turning the engine), or not (TDC on #1)
The cams move very slowly when you're hand cranking.
The V change on multimeter will probably not tell you anything. You need at least something like an oscilloscope to tell you the data curve. The hall effect sensor generates square wave as the notches of the gear pass by it. There are probably 40 notches on the gear so you will see that many waves in each rotation. Multimeter will only show you the voltage fluctuating all the time.
You will need to monitor both crank sensor and cam sensor. When it's at compression TDC both sensors will have a miss, while when it's at exhaust TDC only the crank sensor has a miss. The slow moving of the gear will make the signal not very strong that's why I said you need an oscilloscope or something to directly show the data curve. There will probably only be a small excitement at each notch.
Last edited by geniushanbiao; May 20, 2020 at 01:46 PM.
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2012 ML350 Bluetec, 2015 GL350 Bluetec
The exhaust pressure sensor is mounted around the DPF so it's after the turbo, so I'd suggest first make sure the guide vanes of the turbo are properly closed when you are idling. If they are not closing then you have exhaust going into the turbo that pushes the turbo to turn, then obviously the exhaust pressure will be low and you have some boost pressure as shown in the data you posted. If the engine can rev up, you should see the vanes opening when the rpm goes higher than 1500-2000rpm. The vanes are controlled electronically and by a lever so there's also an option for you to disconnect the arm and move by hand. By doing that you can manually close the vanes and see if the data changes. You can see the lever if you remove the heat shield of the turbocharger (3 bolts). It's behind the electronic controller on the passenger side of the turbo.
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Joined: Apr 2020
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From: Lille, France
2009 E350 CDI Bluefficiency 4matic
Again like I said, I'd suggest you not swap parts randomly at first. There's not too much chance those sensors go bad unless you intentionally destroy them. You want to assume they are working fine in the first place than swapping randomly. Some poorly trained mechanics like to start with blaming the sensors when they have no clue of the symptom, and I think this is a very bad way of thinking. Don't learn this from them.
The exhaust pressure sensor is mounted around the DPF so it's after the turbo, so I'd suggest first make sure the guide vanes of the turbo are properly closed when you are idling. If they are not closing then you have exhaust going into the turbo that pushes the turbo to turn, then obviously the exhaust pressure will be low and you have some boost pressure as shown in the data you posted. If the engine can rev up, you should see the vanes opening when the rpm goes higher than 1500-2000rpm. The vanes are controlled electronically and by a lever so there's also an option for you to disconnect the arm and move by hand. By doing that you can manually close the vanes and see if the data changes. You can see the lever if you remove the heat shield of the turbocharger (3 bolts). It's behind the electronic controller on the passenger side of the turbo.
The exhaust pressure sensor is mounted around the DPF so it's after the turbo, so I'd suggest first make sure the guide vanes of the turbo are properly closed when you are idling. If they are not closing then you have exhaust going into the turbo that pushes the turbo to turn, then obviously the exhaust pressure will be low and you have some boost pressure as shown in the data you posted. If the engine can rev up, you should see the vanes opening when the rpm goes higher than 1500-2000rpm. The vanes are controlled electronically and by a lever so there's also an option for you to disconnect the arm and move by hand. By doing that you can manually close the vanes and see if the data changes. You can see the lever if you remove the heat shield of the turbocharger (3 bolts). It's behind the electronic controller on the passenger side of the turbo.
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2012 ML350 Bluetec, 2015 GL350 Bluetec
The controller do go bad though. But if it's new and comes with the turbo assembly you replaced with, I'd suspect it needs to be taught in.
An exhaust leak can also cause low exhaust pressure, but since you have an abnormally high boost I'd suspect the turbo is being pushed running unexpectedly when idling.
Last edited by geniushanbiao; May 20, 2020 at 03:42 PM.
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From: Lille, France
2009 E350 CDI Bluefficiency 4matic
Well if the turbo is new then I'd suspect it's not installed properly or something. By saying turbo is new what parts are new and how did you replace it? The turbocharger assembly contains a lot of parts. While you can buy the whole assembly, I know some people replace only the turbo cartridge instead of the whole thing. That will save a lot of cost. However when replacing the cartridge the housings need to be precisely oriented when installing otherwise it will have issue during operation. There are some cartridges from China that need some modification to work as well.
The controller do go bad though. But if it's new and comes with the turbo assembly you replaced with, I'd suspect it needs to be taught in.
An exhaust leak can also cause low exhaust pressure, but since you have an abnormally high boost I'd suspect the turbo is being pushed running unexpectedly when idling.
The controller do go bad though. But if it's new and comes with the turbo assembly you replaced with, I'd suspect it needs to be taught in.
An exhaust leak can also cause low exhaust pressure, but since you have an abnormally high boost I'd suspect the turbo is being pushed running unexpectedly when idling.
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From: Lawrence, Kansas
GL320
I'm presuming the boost sensor was replaced with one that should not be in that position on the engine. Put your old boost sensor back in and tell me what your reading is. Keep in mind that it is a pressure sensor, not a vacuum sensor like the one on the airbox so if it was not replaced with the exact same part from MB or Bosch or it was not put back in the same position on the engine, it could falsely read that it has 2500 hPa (36psi, or 1500hPa/22PSI (max boost) when removing atmospheric pressure from the reading) at idle when its not. This would also falsely tell the engine that it is already at max boost and disengage the turbo actuator, causing your slow acceleration.
