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Post by Monkey on May 11, 2015 15:00:28 GMT 1
P0087 - fuel rail pressure system too low
Engine goes into loss after acceleration when warm.
Can't see why I'm struggling with this..
Carried out a leak off test. Number 2 injector excessive leak off, changed the injector. Still same code after driven it, every time.
One other injector ever so slightly higher on leak off but NOT excessive.
Has had a fuel filter. Rail sensor checks out ok. Even substituted the fuel pump mounted in the engine bay and still the same.
Any ideas?
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Post by natedog on May 11, 2015 15:12:08 GMT 1
I've seen a couple of threads about this on golfs/jettas that have been run on biodiesel. Does this one run on standard pump fuel, or chip fat homebrew?
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Post by Deleted on May 11, 2015 19:07:31 GMT 1
Cod and chips twice ,
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Post by Deleted on May 11, 2015 19:09:07 GMT 1
Normaly a pump or injector issue mechanical with no other codes, is the low side reliable ?
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Post by Karl on May 11, 2015 19:48:11 GMT 1
Where was the " new injector " from ?
Worth spending to have other 3 tested
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Post by Karl on May 11, 2015 19:52:36 GMT 1
Contamination in fuel tank ?
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Post by Monkey on May 11, 2015 20:21:25 GMT 1
Normaly a pump or injector issue mechanical with no other codes, is the low side reliable ? I think I may have solved it, there's an over pressure valve on the end of the rail with a two pin plug on it and a bleed off pipe running back into the leak off circuit. I blanked the pipe off and ran a tube into a jar, and at idle the valve is leaking a constant flow. Pretty sure that's the prob looks as though engine control can intervene and open the valve however. Doesn't seem to have any control there at idle, and surely should be no flow there whatsoever. I also presume the computer can dump fuel pressure should it need too, hence the two pin plug. Never had anything to do with one of these before. VW junk! Anyone agree? Part is £287 plus the filth. |
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Post by Monkey on May 11, 2015 20:23:01 GMT 1
I've seen a couple of threads about this on golfs/jettas that have been run on biodiesel. Does this one run on standard pump fuel, or chip fat homebrew? Yeah proper fuel |
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Post by Monkey on May 11, 2015 20:23:34 GMT 1
Where was the " new injector " from ? Worth spending to have other 3 tested It's a genuine injector, I never fit junk! |
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Post by valhalla on May 11, 2015 23:40:19 GMT 1
Normaly a pump or injector issue mechanical with no other codes, is the low side reliable ? I think I may have solved it, there's an over pressure valve on the end of the rail with a two pin plug on it and a bleed off pipe running back into the leak off circuit. I blanked the pipe off and ran a tube into a jar, and at idle the valve is leaking a constant flow. Pretty sure that's the prob looks as though engine control can intervene and open the valve however. Doesn't seem to have any control there at idle, and surely should be no flow there whatsoever. I also presume the computer can dump fuel pressure should it need too, hence the two pin plug. Never had anything to do with one of these before. VW junk! Anyone agree? Part is £287 plus the filth. Monkey, You might have the right answer, but for the wrong reason. I have tried to look-up the control system on this engine - as usual nothing in AD - but I'm sure that you are looking at the normal PCV on the end of the rail there. In which case, it should be flowing fuel all the time, if it is in control. I don't think VW have a PCV on the HP pump on these, just a VCV (volume control), and the pressure is dealt-with at the rail for better accuracy. If you have a good scantool, that can clear faults down reliably, then pull the 2-pin plug before trying to start the engine, then see what comes up on the fault list. Irrespective of anything else, the mechanical pressure safety valve will operate completely independently of the ECM, otherwise it wouldn't be there in the first place! |
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Post by Monkey on May 13, 2015 0:08:08 GMT 1
Hi Valhalla
Why would it flow any fuel whatsoever? How's it going to maintain rail pressure?
Haven't got back in to this yet, I removed the PCV to have a look in case anything obvious.. All looks good.
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Post by Monkey on May 13, 2015 15:42:01 GMT 1
The PCV isn't the problem, I manage to compare to another identical car today and that valve leaks off the identical amount..
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Post by Deleted on May 13, 2015 21:04:49 GMT 1
The PCV isn't the problem, I manage to compare to another identical car today and that valve leaks off the identical amount.. Monkey if these fail you have a realy hard time starting, there there for rapid rail pressure changes, i would be suspicious of the injectors like Karl , |
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Post by valhalla on May 13, 2015 22:44:23 GMT 1
Normaly a pump or injector issue mechanical with no other codes, is the low side reliable ?My money is with Mac on this one. It definitely sounds like its worth putting a pressure gauge on both the feed and return lines to the engine, just to confirm you don't have the classic VW symptoms of dodgy low pressure fuel pump when hot. Another way would be to watch the live-data off the ECM for high-pressure control outputs, just to make sure they are not going to their maximum limit (don't know what those limit voltages would be, but anything like a PWM signal of 85% or greater is going to be suspicious). Another think I would look at is the presence of air in the fuel supply, as these problems also get worse when hot, but generally correspond to poor starting as well. |
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Post by Monkey on May 13, 2015 23:23:29 GMT 1
Ok thanks everyone, no starting issues to report whatsoever. Makes sense on PCV valve operation now Mac.
This car seems to have a pump in the tank, a pump in the engine bay next to coolant bottle and obviously the high pressure pump.
I shall have another look tomorrow, I think ultimately the injectors are going to have to be tested to eliminate them!
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