C63 Going nuts !!!
I don't know where to start from , but I changed the spark plugs 3 days ago , on 80k miles I used
Denso (3442) FXE22HR-11 Iridium Long Life Spark Plug
, and today it gave me the check engine light , when i plugged the OBD2 scanner ( not xentry ) it returns these codes
P2541
P0300
P0301
P0302
P0303
P0305
P0171
And when I change the gear from P to D , it chunk , make me feel the car wants to turn off , cuts for 5-7 seconds then start to feel the car is heavier and slower .
P.S : I am going to take the car for diagnosis but want to hear some advices from my beloved members of MBWORLD first

Thank you guys and sorry for my bad English
Last edited by The Lover; Dec 23, 2013 at 02:28 PM.
Secondly.. something is seriously messed up. for the fun of it, I pulled up the trouble codes.
P2541 The fuel pressure sensor of the low pressure circuit has a short circuit to ground.
P0300 Misfiring
p0301 Misfiring of cylinder 1
p0302 Misfiring of cylinder 2
p0303 Misfiring of cylinder 3
p0305 Misfiring of cylinder 5
And I have no clue what P0171 is..
Did you use the right plugs, did you torque them down to spec. Do not run your car as you will cause major damage till you fix it.
P2541 is the low fuel pressure error code
All the P0300 to 305 are the misfiring error code for the respective cylinders.
P0171 is saying your bank 1 is running lean. Too much air, not enough fuel. This one is related to the low fuel pressure code obviously.
And what you guess that cause low fuel pressure error code ?
Also the P0300 codes appeared before I changed the spark plugs , so I thought after Xentry scan I need to replace them on 80k miles , and now reappeared again !!
The low fuel pressure could be caused by a faulty fuel rail pressure sensor or a faulty fuel pump. Why is this showing up now i don't know
.Your next step would be to replace that part and see. Check the fuel injectors as well.
If your engine still misfires then it might be more severe with probably low compression in the cylinders.
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I have done a scan by Xentry
And tested some components ( Fuel Pressure Sensor ) B4/15
And the volt from the Fuel sensor is 4.85 Volt that I checked by a Voltage device, so I guess it's Ok but it shows on Xentry 3.51 bar , and the engine speed is not Ok I guess ,
these are the pictures friends , sorry I'm dizzy trying to figure the issue because I'm not taking it to a dealer to rip off , only if I'm done not figuring the issue then stealer will be the last option !!
Last edited by The Lover; Dec 24, 2013 at 07:16 AM.
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Confirmed they are the correct plugs?
The lean code could be from the back of the air box not sealed properly when it was removed to change plugs.
Confirm fuel pressure. Confirm fuel pressure sensor is not faulty.
I'd try different plugs.
Tranny is clunking because engine is not running good.
Confirmed they are the correct plugs?
The lean code could be from the back of the air box not sealed properly when it was removed to change plugs.
Confirm fuel pressure. Confirm fuel pressure sensor is not faulty.
I'd try different plugs.
Tranny is clunking because engine is not running good.
I dont know if its the fuel pressure or fuel pressure sensor that causing the problem ,i uploaded the xentry resault for fuel pressure and sensor above
Do you think the battary will caus this ?
Regards
is it supposed to be checked with rpm's > 1500 and < 70% load ?
pretty sure it's regulated by a vaccum diaphram
the 647 is idle speed
if the fuel pressure is low that would account for misfires, the lean condition and the low sensor reading
could be:
fuel pump (doubt it since it's making pressure)
bad regulator (not closing the return down to increase rail pressure)
fouled fuel filter (I assume these cars have one)
after looking at some parts diagrams it looks like the pump controls pressure?
could not find a filter, regulator or return/by-pass line?
Last edited by Ingenieur; Dec 24, 2013 at 01:44 PM.
Actually after reading the codes again P2541 seems like the one to go after first. Check to see if any wires look damaged!
Last edited by VividRacing; Dec 24, 2013 at 02:02 PM.
is it supposed to be checked with rpm's > 1500 and < 70% load ?
pretty sure it's regulated by a vaccum diaphram
the 647 is idle speed
if the fuel pressure is low that would account for misfires, the lean condition and the low sensor reading
could be:
fuel pump (doubt it since it's making pressure)
bad regulator (not closing the return down to increase rail pressure)
fouled fuel filter (I assume these cars have one)
after looking at some parts diagrams it looks like the pump controls pressure?
could not find a filter, regulator or return/by-pass line?
Sorry for not understanding you correctly , but what you think is the problem
Should I check the pump control pressure or fuel filter , pherhaps the fuel pump it self , im lost
And thank you for your help
Actually after reading the codes again P2541 seems like the one to go after first. Check to see if any wires look damaged!
But when I try to go on from 0 to high speed it doesnt accelerate immediately , it doesnt respond on time to go fast so there is 2 seconds the car is heavy to accelerate
Sorry for my bad English and thanks for helping me
I rechecked the gaps ( black rubber that close on the spark plugs )
But what I dont understand is why its not accelerating immediately from 0 -100 , it takes seconds to feel the engine responds to accelerate
Thanks again
if it meets spec 4.6 bar, it's most likely not the pump, filter or pressure control
the misfure was occuring before the plugs were replaced
I can't see plugs causing the low fuel pressure/lean faults
some sites list that plug as OE equivilent to the NGK
your sensor is reading so perhaps the pressure IS actually low?
low pressure = reduced fuel delivery rate = lean condition
this would account for the pressure and lean errors
as someone mentioned:
check all the stuff that was removed to do the plugs, especially for air leaks
quoted from diagnostic sites:
"Lean misfire" can occur when the air/fuel mixture is too lean (not enough gasoline in the mixture) to burn. This can be caused by a dirty, clogged or inoperative fuel injector; air leaks; or low fuel pressure because of a weak pump, restricted filter or leaky pressure regulator. Low fuel pressure would affect all cylinders rather than an individual cylinder, as would most air leaks. A leaky EGR valve can also have the same effect as an air leak.
Another common cause would be a fuel delivery issue causing the engine to misfire causing a P0300 code (or any misfire related code) to be stored in the computer. It can be a lack of fuel or too much fuel.
In addition, fuel pressure is a major factor in this too. Low fuel pressure can cause more than just one cylinder to misfire. If the fuel pressure is too low, then the engine will run lean causing it to misfire. If this is the case, your computer may generate a P0171 or a P0300.
Last edited by Ingenieur; Dec 24, 2013 at 02:42 PM.
if it meets spec 4.6 bar, it's most likely not the pump, filter or pressure control
the misfure was occuring before the plugs were replaced
I can't see plugs causing the low fuel pressure/lean faults
some sites list that plug as OE equivilent to the NGK
your sensor is reading so perhaps the pressure IS actually low?
low pressure = reduced fuel delivery rate = lean condition
this would account for the pressure and lean errors
as someone mentioned:
check all the stuff that was removed to do the plugs, especially for air leaks
quoted from diagnostic sites:
"Lean misfire" can occur when the air/fuel mixture is too lean (not enough gasoline in the mixture) to burn. This can be caused by a dirty, clogged or inoperative fuel injector; air leaks; or low fuel pressure because of a weak pump, restricted filter or leaky pressure regulator. Low fuel pressure would affect all cylinders rather than an individual cylinder, as would most air leaks. A leaky EGR valve can also have the same effect as an air leak.
Another common cause would be a fuel delivery issue causing the engine to misfire causing a P0300 code (or any misfire related code) to be stored in the computer. It can be a lack of fuel or too much fuel.
In addition, fuel pressure is a major factor in this too. Low fuel pressure can cause more than just one cylinder to misfire. If the fuel pressure is too low, then the engine will run lean causing it to misfire. If this is the case, your computer may generate a P0171 or a P0300.
Quoted from
http://www.parts.com/parts/2009/Merc...gramCallOut=14
Thank you for helping
if it meets spec the pump is probably OK
the sensor is reading so I'm guessing it is OK
I'm betting on the pump
I think one pump transfers fuel from one side of the tank to the other
and the other feeds the engine fuel rail
my guess: pump was slowly failing leading to the misfires
finally got low enough to set the low pressure code and lean code
car has 80k miles on it, a failed fuel pump would not surprise me
Last edited by Ingenieur; Dec 24, 2013 at 03:11 PM.
if it meets spec the pump is probably OK
the sensor is reading so I'm guessing it is OK
I'm betting on the pump
I think one pump transfers fuel from one side of the tank to the other
and the other feeds the engine fuel rail
my guess: pump was slowly failing leading to the misfires
finally got low enough to set the low pressure code and lean code
car has 80k miles on it, a failed fuel pump would not surprise me
the fuel pressure test says to test it at idle - hence the part where it says engine idling. clearly the fuel pressure actual value is not at the specified. Fuel pressure is regulated by the fuel pump control module. The fuel pump module sends pulse width modulated voltage to the pump not a constant power. Not vacuum diaphram, it's a returnless system - you'd be running a vacuum line all the way to the tank. So you've got a few possibilities.... bad pump, bad sensor, bad fuel pump control module.
This car has 2 fuel pumps. Used on an as needed basis, I believe it actually has a fuel pump module for each pump but its been a while so forgive me if thats wrong. Neither pump transfers fuel from each side of the saddle, this is done with syphoning. at 1/2 a tank it should start transfering all the fuel to the right side of the tank - passenger side, where the pumps are.
Just dont go jumping a constant 12v to the fuel pumps as this will fry them. The car actually will run suprisingly well on one pump, It'll only throw the low pressure code under full load if thats the case though.
I dont understand how you guys have access to xentry and then claim the "stealership" is too expensive where are ya'll getting xentry/das machines?






