Mercedes:P0087:Start-Run-Stall-Fix! Test/Don't Guess!
Vložit
- čas přidán 9. 09. 2024
- This 2015 Mercedes GLA250 was a tough one to diagnose, but through all the testing I finally got it figured out. There are many components to today's vehicles fuel systems, and this is a clear example of how to determine an issue with it.
You sound like an informative professional that's not a prick That's what's up I appreciate your work
Thank you 👍
By the way I was able to fix my problem My battery voltage dropped to 9 volts while starting and I didn't have to buy a fuel pump I just needed a new battery 2013 ML550
Yoda would bow in your presence, Sadel. Thanks for sharing your knowledge with us!
This was a real head scratcher. I appreciate the final thought in closing! Makes sense the module may see an issue with the motor windings. Maybe a short in there somewhere, causing the amperage spike?
Good stuff! Thanks for sharing!
Yes it seems to be a high amperage issue that it sees and shuts off. Thank you for watching
Nicely done sir👍🏻 Like how thorough you are in your diagnostics. 8 channel scope seems like a must nowadays when trying to pinpoint some of these faults. Just so many possible points of failure for any single system nowadays.
yes the 8 channel definitely helps a ton
Another brilliant teaching moment. Thank you
Glad you enjoyed it & thank you for watching
Hello Sadel. First, I really enjoy your channel. I want to learn things I do not know of and your channel is a blessing. I am very familiar with MB W212 model with M276 3.0 Turbo ( my car ), but not much on other MB models. I want to share what I know, as you also have shared with us your audience what you know.
I believe this C117 CLA250 Mercedes is using M270 DE20LA engine. Since your scanner does not show the VIN number, I am doing best educated guess based on your video.
MB direct injection gasoline engine HP fuel pump and its LP 3 phase fuel pump is basically the same specification on their 200 BAR GDI system across different engines.
200 BAR system by Bosch for HP side. It needs 4 BAR ( 60PSI ) minimum at this HP pump input.
The LP fuel system if filter is clean and new and having the pressure sensor at the filter itself, it should be at 5.8 BAR (84 PSI ) to 6 BAR / 87 PSI.
The head loss starting from LP fuel filter all the way to the input of HP fuel pump and related hoses + distance it covered, if based on W212 E400, read at the LP fuel pressure test port at engine bay using analog mechanical gauge...would be approx 1.2 BAR or 17.4PSI.
So the HP fuel pump still received 5.8 - 1.2 = 4.6 BAR at WOT in 1st and 2nd gear redline to 6,200 RPM.
When you use LP fuel pump actuation on your Autel with engine OFF, and if filter is clean and new, you can read up to 6 BAR/87PSI.
As you seen on your video minutes 40:36. 6 BAR is a regulated pressure, it will self-bleed back to fuel tank at approx 7 BAR.
MB GDI engines, the in tank fuel filter is small, very small. In my country, it can last only at 30,000KM / 18,600 miles or 5,000 liters / 1,322 US gallons of fuel filtering for it to be borderline worthy for WOT operation which is 5.2 BAR / 75.4PSI at fuel filter fuel pressure sensor. 5.2 BAR less 1.2 BAR head loss = 4 BAR at HP fuel pump inlet, at WOT 1st and 2nd gear is what I mean by borderline WOT worthy. I replaced my fuel filter by pressure drop, I do not wait for fuel starvation.
The fuel filter element paper weight is approx 30 grams. So at best 10 grams of 33% of trapped dirt is maximum it can handle before it will start to slow down fuel flow. To achieve 10 grams of dirt from a 5,000 liters of fuel means the dirt in the fuel only need to be at 0.001% at gasoline specific gravity of 0.739 kg per liter. LP fuel filter will be first to be clogged and almost never the HP pump being the issue for such fuel-starvation scenario. The HP pump itself uses fuel as lubricant for its internal rod shape mini piston. Therefore lack of fuel will kill fast this HDP5 Bosch high pressure fuel pump. Dirty fuel will also score the rod shape mini piston. Think of diesel common rail HP pump, same concept, fuel is the lubricant. Yes, engine oil is also the lubricant, but only at some area of the HP pump and not at the internal region where actual fuel pressure boosting occurs.
MB fuel pump controller module is called N118 and it uses CAN BUS for operational control and not PWM as you suspected.
The wire you sensed which you assumed as PWM signal wire, that is a only a signal for actuation of fuel pump ( KSP_A)
Use wiring schematic from MB, it is called : PE47.40-P-2101-97iaa for N118 and Engine Computer N3/10 wiring schematic
PE07.08-P-2101-97iac.
For my W212 using similar N118, the fuel pump controller module will not prime the fuel filter/system by door opening , it only will prime fuel system soonest if in Ignition Key ON engine OFF state..... what US techy will call as KOEO state.
MB N118 fuel pump controller module is kinda stupid if that is the way it behaves on the CLA250 with clogged fuel filter.
Stupid as in : not able to declare dirty fuel filter by using the voltage and amperage PID vs produced fuel pressure.
If for M276 engine computer called Bosch MED177, it has DTC for low fuel pressure at HP pump output which is 24BAR too low from specified pressure. However this ECM does not indicate target/specified HP fuel pressure like an Audi ECM. It only has achieved HP fuel pressure....LOL. So dorky.
allright.....
I hope the information is useful.
That was extremely informative and detailed, Thank you for sharing all of that!
thank you. c250s have a bad rep thank you for clearing something for me. combination of cheap gas and failing low pressure pump caused many c250 to replace HPFP and later replaced low pressure then module. some c250 have "phev" low pressure pump and sport c250 have same low-pressure pump as the 6-cylinder C- class variants.
It would be interesting to measure that fuel pump module control signal coming from the pcm with a current clamp and observe what it's doing. Thank you.
There definitely was a couple things I would have looked at more, but didn't think of it then.
Very interessting.thank for your video.perfect diag 👍🏻👍🏻👍🏻.
Great video!
thank you for watching
Great work 💪..!
WOW!!! amazing video.
i wonder why it did not set the code for low side pump(i think it is p0187).which made your job easier.
Yes, odd that there wasn't a more specific related code. Thank you for watching
High pressure pump cannot deliver high pressure if the low pressure pump does not feed a constant supply at a good enough pressure to handle higher RPM, this is where some techs fail to take the car for a drive under load instead of increased RPM in the shop with no real load to carry down the road. An engine will run in the shop with the HPFP at about the same pressure of a good low pressure pump.
Amp Ramping the low pressure pump can give a lot of information, a visual look at the commutators, math can be done to figure out the RPMs of the pump which can infer the pressure, high RPMs is low pressure, maybe over 7K RPMs, need more of these known good pump RPMs in your library to know.
Good information. But I would venture to say that the engine will not run in the shop with the hpfp at the same psi as the low psi pump.....unless the hpfp is not operational. If an engine is running and the low psi pump is good than the hpfp will raise the psi no matter what. It cannot run at the same psi of the low psi pump, unless it is not compressing the fuel (again, meaning if it is not working). An engine will run with a bad low psi pump (one that runs but creates lower than needed psi) and good hpfp because, again the job of the hpfp is to raise the psi, and so it will take the lower than desired psi from bad low psi pump and raise it enough to idle. Just like this vehicle did.
this low psi pump was drawing too many amps and then the module stopped controlling it, the pump is a 3phase style and an rpm capture would be irrelevant if there is no current being supplied to it (after the module cuts it off).
Saludos desde paraguay bendiciones hermano
and this started when I was driving back home. Suddenly the engine check light came and the full meter went Nil zero and the cars engine full wasn’t going and it was running only on electric mode.. after coming home as well, the car Petrol was not pulling into the engine, ,I am having an issue on my car c350 e
i replaced alot of things
they told me to replace the fuel pump motor. I told them to check the fault. they found out ants on the fuel control module .. I replaced the new full pump motor . as well recondition fuel module . but after getting the car I felt Car has a miss . as well when i rev the car full throttle . cars range was gone . as well when they made the car I went and filled up my tank. but it showed only half tank on the meter. . it never came full tank on the display . after a few days, it was the same. .
no, I have put for another garage.cz it was showing low pressure fuel sensor fault error . they told they have updated the full control module but the fuel reading doesn’t show accurate , really tired of it and stressed . i’m living in a sri lanka. they don’t have mercedes dealer here . i want to know any thoughts and ideas for this issue 😢
Start by checking for correct voltage at the rear fuel pump connector
By the way I was able to fix my problem My battery voltage dropped to 9 volts while starting and I didn't have to buy a fuel pump I just needed a new battery 2013 ML550
Sadile, do you believe the fuel pump module should be replaced as well like when bmw low pressure pumps go bad it takes out the EKP many times.
No, I feel that it is still ok and good, it is seen clearly still having the ability to operate and control the fuel pump each time it's started up. It is just smart enough to shut itself off when the amps stay too high too long. But the key is seeing that it still has control ability each time its re-started
👍👍👍
How does engine ecu detects amp draw of the pump..? Thanks..
On this vehicle its actually the fuel pump computer not the engine computer, and it does it by having means of measuring amperage internally electronically.
What are these scopes/tools called?
the scope I use is from the company Pico, and the scanner is Autel
Saludos desde paraguay bendiciones hermano
and this started when I was driving back home. Suddenly the engine check light came and the full meter went Nil zero and the cars engine full wasn’t going and it was running only on electric mode.. after coming home as well, the car Petrol was not pulling into the engine, ,I am having an issue on my car c350 e
i replaced alot of things
they told me to replace the fuel pump motor. I told them to check the fault. they found out ants on the fuel control module .. I replaced the new full pump motor . as well recondition fuel module . but after getting the car I felt Car has a miss . as well when i rev the car full throttle . cars range was gone . as well when they made the car I went and filled up my tank. but it showed only half tank on the meter. . it never came full tank on the display . after a few days, it was the same. .
no, I have put for another garage.cz it was showing low pressure fuel sensor fault error . they told they have updated the full control module but the fuel reading doesn’t show accurate , really tired of it and stressed . i’m living in a sri lanka. they don’t have mercedes dealer here . i want to know any thoughts and ideas for this issue