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Thread: Mysterious CAYC problem

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  1. Re: Mysterious CAYC problem 
    #11
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    Thanks for that I will check it out
     
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  2. Re: Mysterious CAYC problem 
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    Hi all. Still having major problems with this. I came to the conclusion (wrongly) that the tank fuel pump was at fault but it wasn’t.

    Its defo a fuel problem and I think now that it could be the HP pump.

    I have had the injectors checked/leak back tested and all good.

    On my little diagnostic machine I have the facility to check rail pressures but I don’t k now what they should be and I cant find anything conclusive on the net.
    Can anyone help with this please?

    I have these results but not sure what they mean.
    These are all on cranking the engine over with the starter.

    • Rail pressure, specified value 311 bar max
    • Rail pressure actual, 44 bar max
    • Rail pressure control deviation, 272 bar


    Just to remind it’s a SEAT Leon with CAYC engine. 1.6 TDi

    Thanks all
     
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  3. Re: Mysterious CAYC problem 
    #13
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    Quote Originally Posted by Bodevo View Post
    Hi all. Still having major problems with this. I came to the conclusion (wrongly) that the tank fuel pump was at fault but it wasn’t.

    Its defo a fuel problem and I think now that it could be the HP pump.

    I have had the injectors checked/leak back tested and all good.

    On my little diagnostic machine I have the facility to check rail pressures but I don’t k now what they should be and I cant find anything conclusive on the net.
    Can anyone help with this please?

    I have these results but not sure what they mean.
    These are all on cranking the engine over with the starter.

    • Rail pressure, specified value 311 bar max
    • Rail pressure actual, 44 bar max
    • Rail pressure control deviation, 272 bar


    Just to remind it’s a SEAT Leon with CAYC engine. 1.6 TDi

    Thanks all
    I have a cayc too with a slightly worn to some degree but functioning hpfp, the starting pressure on mine is 4400psi and it drops back to about 3300 once on idle.

    Check for metal shavings / swarf in the system. Bleed the system after check if needed. This is the critical check. Was there metal swarf in the fuel filter and fuel tank?
     
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  4. Re: Mysterious CAYC problem 
    #14
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    Thanks for that. There was a tiny bit of swarf when I changed the filter. I mean just 2 tiny bits. Nothing in the tank.
    So 4400 psi is about 300 bar so if my rail pressure actual is 44 bar thats only about 600 psi. Question is what is the rail pressure, specified value? This is 311 bar on mine and it changes when I crank the engine over. I suspect that the actual pressure will be the one to go by but just want to be sure before I start striping the pump out.
    Thanks again
     
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  5. Re: Mysterious CAYC problem 
    #15
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    If there is ANY ally swarf in there, the pump is damaged.
    Anthropogenic climate change, the biggest con inflicted on mankind since religion...

    Slava Ukraini
    !


     
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  6. Re: Mysterious CAYC problem 
    #16
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    Quote Originally Posted by Bodevo View Post
    Thanks for that. There was a tiny bit of swarf when I changed the filter. I mean just 2 tiny bits. Nothing in the tank.
    So 4400 psi is about 300 bar so if my rail pressure actual is 44 bar thats only about 600 psi. Question is what is the rail pressure, specified value? This is 311 bar on mine and it changes when I crank the engine over. I suspect that the actual pressure will be the one to go by but just want to be sure before I start striping the pump out.
    Thanks again
    It doesn't seem to be a straight forward case of pump cam breaking up but it's always to be suspected. As even 1 piece of swarf can lodge in the wrong place.
    I actually do not know specified fuel pressure value since the system hasn't missed a beat (my heart has due to finding sparkles on filter top when changing the fuel filter last week, hence acknowledgement that my hpfp is worn to some degree)

    The above figure has not changed much on mine since I first checked it about 1.5 years ago (iirc remember 4231psi), so assume it'll be about that much.

    I can help with diagnostic overview info on the fuel system. The fuel metering valve is normally closed, hence if not stuck open or not operated the system can not build pressure. The regulating valve (on the rail) opens to allow drops of fuel to escape through return line thereby lowering the fuel pressure. These two valves work to regulate the fuel pressure. The pressure sensor just measures the pressure inside the rail. The return line has a check valve to maintain minimum back pressure.

    The fuel metering valve and fuel regulating valve normally run around 20%duty cycle. Mine was 24% and 16% last time I checked but you might struggle to read anything if its not starting

    The wiring can suffer from rubbing of the loom all the way back to the battery area. This causes faults on the effected sensor of whichever wire is damaged.
     
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  7. Re: Mysterious CAYC problem 
    #17
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    Hi Thanks for making the effort to reply.
    I removed the solenoid and it was spotlessly clean. Whilst I had it off I blanked off the hole to try and eliminate the solenoid as the problem. I used a plate and O ring which sealed well. I then plugged in the solenoid and tried to start but no joy. I did notice that the solenoid was making a "chattering" noise with the ignition on though. Is this normal?
    I have checked wiring several times but cant see anything obvious. I will have to take some stuff out and dig deeper.
    She will sometimes start and run for a few seconds then start missing, coil light flashes on and then cuts out
    Thanks again
     
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  8. Re: Mysterious CAYC problem 
    #18
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    Quote Originally Posted by Bodevo View Post
    Hi Thanks for making the effort to reply.
    I removed the solenoid and it was spotlessly clean. Whilst I had it off I blanked off the hole to try and eliminate the solenoid as the problem. I used a plate and O ring which sealed well. I then plugged in the solenoid and tried to start but no joy. I did notice that the solenoid was making a "chattering" noise with the ignition on though. Is this normal?
    I have checked wiring several times but cant see anything obvious. I will have to take some stuff out and dig deeper.
    She will sometimes start and run for a few seconds then start missing, coil light flashes on and then cuts out
    Thanks again
    Its not supposed to start with metering valve closed or even disconnected, so that's good and well. I would take the plug out ASAP because the metering valve may have a bypass to some extent to keep pump lubricated.
    I'd hold the metering valve in my hand and try to gauge its range of movement, and or if its operating OK. You might need to disconnect Intank fuel pump for this so you don't end up with fuel everywhere when you turn ignition on.


    From my understanding, if we are dealing with issue of fuel pressure too high you are looking at a fuel regulating valve stuck closed as the primary suspect, followed by metering valve stuck open. A major source of pressure relief is the injectors themselves, and obviously it has to be measured correctly by the pressure sensor.

    The regulator is a one time use only, so in order to check it I'd open its outlet port (leak off pipe) carefully, although that may be also a one off connection its lower pressure side, rather then remove the valve itself.

    I'll check the metering valve noise and let you know later. There is a faint chatter from the area when running and I've assumed thats normal.
     
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  9. Re: Mysterious CAYC problem 
    #19
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    Sorry mate, for some reason I thought the problem was pressure too high but it's pressure too low after reading your post elsewhere

    Right for that the whole thing is reversed. Possible regulating valve stuck open, metering valve stuck closed, Pump mechanical condition, injector leak off, supply restriction.
     
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  10. Re: Mysterious CAYC problem 
    #20
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    No you are correct. The original code that came up was: P228DOO - FUEL METERING VALVE, CONTROL VARIATION - PRESSURE TOO HIGH - PERMANENT
    Not sure if that was an old one though as its not shown itself since.
    cheers
     
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