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Post by jmh474 on Sept 11, 2020 9:31:49 GMT 1
So im pretty much ran out of patience now 😂, iv spoken to other forums and its a case of people dont want to help me or dont know what to do.
As the title suggests its about a bmw x5 3.0l diesel sport 2004.
Im buying this car off my next door neighbour for a grate price, but as we was looking around the car it was ticking over and just cut out, tried starting it again but nothing.
So he put his diagnostic laptop on it and read the obd and it was showing low fuel rail pressure, so this is where the list of jobs starts.
So far this is what we have done,
Checked all fuses and relays and there all fine.
Changed the fuel filter.
Changed the fuel pump under the passenger seat.
Checked the cam and crank sensors and there fine.
Changed the fuel rail pressure sensor.
Done a leak back test and the results are fine.
Checked to see the injectors are firing.
Tried a little easy start to get it to turn over, it will start but when we stop spraying it just cut out and sound like a bag of s**t.
The last thing we've tried is reconditioning the high pressure pump and i was quit gunky inside and replaced the high pressure pump sensor.
One thing to note is common rail pressure is still only reading 300 psi so im guessing iv got a pressure problem but im not sure where else to look.
Any advice would be much appreciated as im really starting to loss my patience with it and the car iv got now is not in the best of shape
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Post by trickydicky on Sept 11, 2020 10:28:04 GMT 1
What is the exact fault code??
What fuel pressure does the Fuel Rail Pressure sensor report at rest/during cranking??
Are you 100% sure you have enough fuel in the tank?
Can you run the intank pump and measure the actual low-side pressure/volume?
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Post by jmh474 on Sept 11, 2020 10:54:48 GMT 1
What is the exact fault code?? What fuel pressure does the Fuel Rail Pressure sensor report at rest/during cranking?? Are you 100% sure you have enough fuel in the tank? Can you run the intank pump and measure the actual low-side pressure/volume? I can't quite remember the fault code sorry but when i searched the code it was low fuel rail pressure The car wont fire but low pressure side is reading 3.5 bar And when cranking high pressure is reading 300 bar. I have just had one though could an injector be stuck open and would this stop the car from firing? These 1/4 of a tank to she be enough |
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Post by trickydicky on Sept 11, 2020 12:55:01 GMT 1
That should be enough pressure during cranking, Usually see 220-250bar during cranking
Are you 100% sure its good fuel??
Crank/Cam timing Ok?
See if you can get all the DTCs from all modules for us
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Post by jmh474 on Sept 13, 2020 16:59:39 GMT 1
Yeah fuels all good
Cam and crank sensors test out fine
Im not reading any error codes which i find strange but is that because its not firing
Iv got a k + dcan cable coming and ill be installing ista and inpa and advice on what to look out for with the software or pictures worth posting that may help
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remmington
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Post by remmington on Sept 13, 2020 18:39:38 GMT 1
That should be enough pressure during cranking, Usually see 220-250bar during cranking Are you 100% sure its good fuel?? Crank/Cam timing Ok?See if you can get all the DTCs from all modules for us My thoughts are the same - chain jumped? |
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Post by jmh474 on Sept 13, 2020 20:09:01 GMT 1
If the chain has jumped how would i find out as this is a little out of my league, but iv not got the money to pay out for a
mechanic to look over the car unfortunately as i care for my son full time so any help would be grateful
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remmington
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Post by remmington on Sept 13, 2020 20:38:04 GMT 1
If the chain has jumped how would i find out as this is a little out of my league, but iv not got the money to pay out for a mechanic to look over the car unfortunately as i care for my son full time so any help would be grateful A "bmw x5 3.0l diesel sport" are not cars for people with no money! You need to extract the error codes - see if there is any codes for the "Ex cam". What did you extract the live data with to get the rail pressure when cranking with? |
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Post by valhalla on Sept 13, 2020 23:36:09 GMT 1
Agree with the help above - but a bit worried about the description that the CR pump was "gunky inside"
I would expect a cam/crank synchronisation code to come up on the scantool if the chain has jumped - is this a decent scantool that you have used up to now?
Did you change the rail pressure sealing-washer with the new rail pressure sensor that went into the rail? These will often throw the rail pressure readings out, but I'd be surprised if that was the cause of the engine just dying at idle - I'm thinking more on the lines that the old rail pressure sensor might have died, and you have replaced with a new sensor that is also not reading properly.
What I would be looking for here is excessive back-pressure on the rail pressure control as well as a good supply feed pressure. 3.5BAR input pressure at the CR pump would need to be gauge pressure, not absolute pressure, to get this engine started, so are you measuring this over the scantool? A proper tapped-in pressure transducer or accurate gauge would give more reassurance that the fuel feed is OK. You should be seeing 1.0BAR absolute pressure on the LP sensor when the engine is stopped, and 4.2BAR on the same sensor when the LP pump is running (before/during cranking).
Be aware that if errors exist on fuel pressure controls, default readings are substituted into the working parts of the engine control structures, so you are looking to see that both the low pressure (LP) and high pressure (HP) signals inside the controller are actually moving as you crank the engine. A generic OBD interface will not give you the correct information to see this - you are looking for raw signal voltages over the BMW generic software to see movements.
I think that your CR pump (the HP pump) is goosed if it is contaminated, as the internal control valve for pressure cannot function properly in that environment. These have to be ultra clean inside, not just "very clean to diesel engine standards", and the cleanliness specs are phenomenally tight from Bosch. It sounds like this has been run on high bio-content diesel fuel, then allowed to stand around for several weeks quietly growing bio-gel in the fuel lines and filter. At the very best scenario, you should be considering removing the CR pump and have it overhauled by a Bosch agency, but before doing that, you need to eliminate absolutely everything else first; good fuel supply, good fuel return, good wiring to the CR pump and sensor, and re-check that a decent power-supply exists from Bosch ECU to the fuel sensors/actuators by back-probing with a decent multimeter.
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remmington
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Post by remmington on Sept 13, 2020 23:47:04 GMT 1
Agree with the help above - but a bit worried about the description that the CR pump was "gunky inside" I would expect a cam/crank synchronisation code to come up on the scantool if the chain has jumped - is this a decent scantool that you have used up to now? Did you change the rail pressure sealing-washer with the new rail pressure sensor that went into the rail? These will often throw the rail pressure readings out, but I'd be surprised if that was the cause of the engine just dying at idle - I'm thinking more on the lines that the old rail pressure sensor might have died, and you have replaced with a new sensor that is also not reading properly. What I would be looking for here is excessive back-pressure on the rail pressure control as well as a good supply feed pressure. 3.5BAR input pressure at the CR pump would need to be gauge pressure, not absolute pressure, to get this engine started, so are you measuring this over the scantool? A proper tapped-in pressure transducer or accurate gauge would give more reassurance that the fuel feed is OK. You should be seeing 1.0BAR absolute pressure on the LP sensor when the engine is stopped, and 4.2BAR on the same sensor when the LP pump is running (before/during cranking).
Be aware that if errors exist on fuel pressure controls, default readings are substituted into the working parts of the engine control structures, so you are looking to see that both the low pressure (LP) and high pressure (HP) signals inside the controller are actually moving as you crank the engine. A generic OBD interface will not give you the correct information to see this - you are looking for raw signal voltages over the BMW generic software to see movements. I think that your CR pump (the HP pump) is goosed if it is contaminated, as the internal control valve for pressure cannot function properly in that environment. These have to be ultra clean inside, not just "very clean to diesel engine standards", and the cleanliness specs are phenomenally tight from Bosch. It sounds like this has been run on high bio-content diesel fuel, then allowed to stand around for several weeks quietly growing bio-gel in the fuel lines and filter. At the very best scenario, you should be considering removing the CR pump and have it overhauled by a Bosch agency, but before doing that, you need to eliminate absolutely everything else first; good fuel supply, good fuel return, good wiring to the CR pump and sensor, and re-check that a decent power-supply exists from Bosch ECU to the fuel sensors/actuators by back-probing with a decent multimeter.
Would agree with Vallhalla on his quote "3.5BAR input pressure at the CR pump would need to be gauge pressure, not absolute pressure". T in gauge at 3.5bar with fuel flow would start an engine - but gauge against a running electric fuel pump is another thing - we call this a "dead end" test. This needs to be a lot over 4bar... Volume and pressure are two differing things - these little LP pumps don't actually move that much fuel (as your engine does not use that much fuel). |
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Post by givusaclue on Sept 14, 2020 7:43:32 GMT 1
Is your cranking pressure 300psi or 300bar? You’ve quoted both in your posts
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remmington
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Posts: 4,966
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Post by remmington on Sept 14, 2020 9:39:04 GMT 1
Is your cranking pressure 300psi or 300bar? You’ve quoted both in your posts 300psi / 14.4 = 20.83 bar |
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