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I got those, the whole kit. I will do the test tomorrow. Are you sure I can do the test w/o cranking? And why not cranking? Also, there is a weird code that keeps popping up - C42700 implausible data from the steering column and lock.
I meant that you first see if you see any leak without cranking, just to make sure the injectors are not leaking badly with even a low pressure (49psi as you said). You can also do this by unplugging the injectors and cranking -- that will give higher rail pressure and ensure the injectors are not actually leaking. Then you can crank and see the leakdown.
Theoretically the leak down test should be done when engine is running, so you have the normal rail pressure (~23000psi) and that will tell you how the injectors are working. For now what you need to make sure is just there's no injector leaking badly that's causing the rail pressure not building up.
I meant that you first see if you see any leak without cranking, just to make sure the injectors are not leaking badly with even a low pressure (49psi as you said). You can also do this by unplugging the injectors and cranking -- that will give higher rail pressure and ensure the injectors are not actually leaking. Then you can crank and see the leakdown.
Theoretically the leak down test should be done when engine is running, so you have the normal rail pressure (~23000psi) and that will tell you how the injectors are working. For now what you need to make sure is just there's no injector leaking badly that's causing the rail pressure not building up.
So, I did the leak teat today and no amount of fuel came out of any of the injectors. Also cranked the engine, no fuel out. I have some pictures with data, I hope you guys can take a look and share your opinion.
OK if no fuel comes out then it can be concluded that the injectors are not leaking and the HPFP cannot build enough pressure in the rail. That can also be seen in the data from the fuel rail pressure sensor. Anything less than 100 bar is essentially 0. I think it's for sure that you need to rebuild your HPFP.
There should always come some fuel out from inectors when cranking, but because of poor 40 bar rail pressure that is reduced for sure. But still if ijectors opens, always fuel comes out from tank line. Now its either fuel starvation on bad leak somewhere else. I just wonder why injector try inject (30-50mm^3) because injection permission should be given only after enough rail pressure (around 150-200 bar).
There should always come some fuel out from inectors when cranking, but because of poor 40 bar rail pressure that is reduced for sure. But still if ijectors opens, always fuel comes out from tank line. Now its either fuel starvation on bad leak somewhere else. I just wonder why injector try inject (30-50mm^3) because injection permission should be given only after enough rail pressure (around 150-200 bar).
The injectors are basically valves and the 30-50mm^3 represents how long it lifts the gate. The way it works is that with electric signal sent to the injectors from the controller, the piezo will reshape a little bit (on the order of microns) and give such clearance for the fuel to pass while atomize. Basically the data from the computer shows how much it's lifting the piezo. However if there's not enough pressure on the fuel rail it cannot pass the nm to um range clearance into the combustion chamber or return line. So the fuel pressure is the culpit.
OK if no fuel comes out then it can be concluded that the injectors are not leaking and the HPFP cannot build enough pressure in the rail. That can also be seen in the data from the fuel rail pressure sensor. Anything less than 100 bar is essentially 0. I think it's for sure that you need to rebuild your HPFP.
OK, the pump is probably the reason then. Do you think a rebuild kit will do the job? The pump is not leaking I think. If there is a fuel leak someplace, where would that be?
Under 200 bar pressure ECU should not give any injection commands however
I don't think the ECU is built with such logic. The injection amount is calculated by lambda, load and intake air mass/pressure. The rail pressure will provide correction that lower than spec rail pressue will result in increase of fuel injection to compensate for the insufficient pressure, not reducing.
I don't think the ECU is built with such logic. The injection amount is calculated by lambda, load and intake air mass/pressure. The rail pressure will provide correction that lower than spec rail pressue will result in increase of fuel injection to compensate for the insufficient pressure, not reducing.
Its 40 bar that is enough to lift injector, true I have not seen low pressure case where I would checked injected amount, but its stated in manly places its around 200 bars when injection starts. If injectro is capable to do it after 40 bars, why such limit?
I was always wondering that advice. Very true, pressure wave travels in rail and cause problems, even at full run. I have seen this happening in marine diesels. But during start, speed always varies a bit and pressure wave is highly depending on interference between pump piston timing and injection timing; resonance is happening only at certain frequencies = rotation speeds. And older HP pumps had only two possible 'timings' since slot ables only two 180 deg positions.
OK I see the issue. The timing is required for earlier version of OM642 and the procedure is detailed in the WIS. However for later version of OM642 the timing is not required any more. At least on my 2012 and 2015 the WIS simply tells me to install the HP pump any way I want, while I put in a random 164.122 chasis in the search it gives me a detailed timing procedure when reinstalling the HP pump. If you need I can share the document.
Its 40 bar that is enough to lift injector, true I have not seen low pressure case where I would checked injected amount, but its stated in manly places its around 200 bars when injection starts. If injectro is capable to do it after 40 bars, why such limit?
The pressure in the rail is not used to lift the injector. The injector is like a "gate" that blocks the fuel and the electronic signal lifts the gate. Those high pressure injectors work in a slightly different way that the actual "gate clearance" is only on the order of micrometers or even nanometers since they use piezo, so it requires a very high fuel pressure to pass the clearance. If the pressure is not enough no fuel can pass the lifted gate. It's not like those low pressure injectors you can find on port injected gas engines.
It's just the same thing as if you have a small leak in a gasket and it requires a certain pressure to have any fluid (oil, water, etc) to actually leak out.
Dont worry, I do know how common rail injectors work. I was erratically referring pilot stage spring force, which is actually delta pressure over control orifice
OK I see the issue. The timing is required for earlier version of OM642 and the procedure is detailed in the WIS. However for later version of OM642 the timing is not required any more. At least on my 2012 and 2015 the WIS simply tells me to install the HP pump any way I want, while I put in a random 164.122 chasis in the search it gives me a detailed timing procedure when reinstalling the HP pump. If you need I can share the document.
Not sure if mine does, but if you could share it would be great.
Do you think I should buy WIS clone from China? Is it worth it? How would I know the specs for the HP? Let say I would like to rebuild it, I will get the O-rings kit, but what do I measure to check the specifics? I would like to salvage the HP if possible.
Not sure if mine does, but if you could share it would be great.
Do you think I should buy WIS clone from China? Is it worth it? How would I know the specs for the HP? Let say I would like to rebuild it, I will get the O-rings kit, but what do I measure to check the specifics? I would like to salvage the HP if possible.
This is the one I found for a 642.940 engine on a 164.122 chasis. If you give me your VIN I can verify if it's the same.
I got mine from a vendor on Ebay. It's only $10 so definitely worths it.
For the specs of the HP pump, Mercedes document wouldn't have it. You can take a look at the stamped info on the pump to get the manufacturer information, then look for rebuild kit for the specific model (the manufacturer model, not MB part number).
The pump and injectors are all different in early version vs later version of OM642. My 2012 and 2015 definitely don't need the "timing" procedure in this document. From EPC the injectors on my 2012 are 6420701187 while I put in a 164.122 chasis it gives me 6420701387 as the injectors part number. The HP pump on my 2012 is 6420701301 while the one on the 164.122 is 6420700301.
This is the one I found for a 642.940 engine on a 164.122 chasis. If you give me your VIN I can verify if it's the same.
I got mine from a vendor on Ebay. It's only $10 so definitely worths it.
For the specs of the HP pump, Mercedes document wouldn't have it. You can take a look at the stamped info on the pump to get the manufacturer information, then look for rebuild kit for the specific model (the manufacturer model, not MB part number).
The pump and injectors are all different in early version vs later version of OM642. My 2012 and 2015 definitely don't need the "timing" procedure in this document. From EPC the injectors on my 2012 are 6420701187 while I put in a 164.122 chasis it gives me 6420701387 as the injectors part number. The HP pump on my 2012 is 6420701301 while the one on the 164.122 is 6420700301.
Here is the VIN WDD2120891A101459. So, you don't have the STAR clone, just a manual for mercedes? I was talking about this - https://bit.ly/2X3KczZ.
Here is the VIN WDD2120891A101459. So, you don't have the STAR clone, just a manual for mercedes? I was talking about this - https://bit.ly/2X3KczZ.
OK based on the VIN you should have 6420700501 or 6420701201 equipped. The EPC says 6420701201 is not for US or Japan version so I believe you have the 6420700501 but I'm not 100% sure. You might want to take a look at the stamped part number. The pump is older version so timing is required. I attached the document again but it should be the same as the one I attached last time.
I have a Xentry clone from a Chinese vendor, just like the one in your link. This is the diagnostic tool to talk to the computer. The EPC, WIS/ASRA is a different thing. It's a digital document that shows you all part numbers equipped and the step-by-step procedure to perform each repair work. Check this link. https://www.ebay.com/itm/Latest-2019...1acb26a6d03205
If you buy the Star/Xentry clone, it might have WIS built in but I didn't see it in mine. It's better to run the WIS and Star on 2 different computers.
OK based on the VIN you should have 6420700501 or 6420701201 equipped. The EPC says 6420701201 is not for US or Japan version so I believe you have the 6420700501 but I'm not 100% sure. You might want to take a look at the stamped part number. The pump is older version so timing is required. I attached the document again but it should be the same as the one I attached last time.
I have a Xentry clone from a Chinese vendor, just like the one in your link. This is the diagnostic tool to talk to the computer. The EPC, WIS/ASRA is a different thing. It's a digital document that shows you all part numbers equipped and the step-by-step procedure to perform each repair work. Check this link. https://www.ebay.com/itm/Latest-2019...1acb26a6d03205
If you buy the Star/Xentry clone, it might have WIS built in but I didn't see it in mine. It's better to run the WIS and Star on 2 different computers.
OMG!! This is so ****ing weird! Sorry for my language. I had a leak I just discovered under the car. At first I wasnt' able to see the origin. But then I noticed the top of the engine was wet - right under the batwing (can't notice it with the wing installed. So, I went ahead and re-tightened all HP fuel lines going to the injectors. First crank and the car started. No more leak either. My head just exploded. I Swear I followed the torx reqs for those. I have spent 3 weeks on this engine and finally there is the reason for low pressure. Dear Lord!! Now the car runs smooth, but I think its in limp modes. I know I have bad boost sensor on the EGR valve. But, look at the data from the scanner. It seems to me the exhaust pressure is low for that reason. Any ideas? Also IAT pressure?? Another weird code popped up - faulty DPF. Data showes very low ashes and soot - almost 0.
geniushanbiao, I already bought the manual from the link (thank you much for that). The HP pump is leaking from the bottom screw. I guess I will have to get that kit for it. So far good data for the pressure. See the pictures:
OK based on the VIN you should have 6420700501 or 6420701201 equipped. The EPC says 6420701201 is not for US or Japan version so I believe you have the 6420700501 but I'm not 100% sure. You might want to take a look at the stamped part number. The pump is older version so timing is required. I attached the document again but it should be the same as the one I attached last time.
I have a Xentry clone from a Chinese vendor, just like the one in your link. This is the diagnostic tool to talk to the computer. The EPC, WIS/ASRA is a different thing. It's a digital document that shows you all part numbers equipped and the step-by-step procedure to perform each repair work. Check this link. https://www.ebay.com/itm/Latest-2019...1acb26a6d03205
If you buy the Star/Xentry clone, it might have WIS built in but I didn't see it in mine. It's better to run the WIS and Star on 2 different computers.
OMG!! This is so ****ing weird! Sorry for my language. I had a leak I just discovered under the car. At first I wasnt' able to see the origin. But then I noticed the top of the engine was wet - right under the batwing (can't notice it with the wing installed. So, I went ahead and re-tightened all HP fuel lines going to the injectors. First crank and the car started. No more leak either. My head just exploded. I Swear I followed the torx reqs for those. I have spent 3 weeks on this engine and finally there is the reason for low pressure. Dear Lord!! Now the car runs smooth, but I think its in limp modes. I know I have bad boost sensor on the EGR valve. But, look at the data from the scanner. It seems to me the exhaust pressure is low for that reason. Any ideas? Also IAT pressure?? Another weird code popped up - faulty DPF. Data showes very low ashes and soot - almost 0.
geniushanbiao, I already bought the manual from the link (thank you much for that). The HP pump is leaking from the bottom screw. I guess I will have to get that kit for it. So far good data for the pressure. See the pictures:
Did you make sure the mating surface is perfectly clean before connecting? The HP lines are very very sensitive to contamination and MB calls for any repair work with fuel line opening done under low dust condition. Also the nuts should be tightened when the rails are loose from the cylinder head. That will make sure the metal gasket is positioned correctly. Also how did you measure the torque? My understanding is that it's almost impossible to ensure the torque without the special adapter tool that you can attach the torque wrench to. I simply used my open end wrench and feeled the torque by hand.
Not sure why the intake pressure is so low. Is your air filters clogged?
Last edited by geniushanbiao; 05-18-2020 at 06:12 PM.
Did you make sure the mating surface is perfectly clean before connecting? The HP lines are very very sensitive to contamination and MB calls for any repair work with fuel line opening done under low dust condition.
Not sure why the intake pressure is so low. Is your air filters clogged?
Yes, checked surfaces before assemble. Filters are newish ..... chinese, not original. I think the other sensor may be bad too. But both sensors?
what are sensors showing engine stopped (atm pressure all)? Adaption values should be reset after filter change in OM642.
They are showing, but I swapped the 2 sensors and the one showing the high value of 2500 is definitely bad. I did not change the AIr filters, only fuel filter. I never did an adaptation to air filter change and never had a problem.
05-15-2020, 05:58 PM
