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  1. #1
    Senior Member Two Rings MugelloB7RS4's Avatar
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    Drivability Problem

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    Hey guys, I need someone elses brain on this one.

    I've had an intermittent drivability issue over the past 6-8 months. The car will randomly run very rough as if it's running on 6 cylinders. Rough idle, down on power, just not running well. Sometimes restarting the ignition helps, but more so than that, I've noticed that fuel system cleaner seems to work and makes it run well again for another tank or two.

    It's had 2 intermittent codes all the while.

    - High Pressure Fuel Sensor G247 Malfunction - Intermittent
    - Fuel pressure regulator valve N276 Open Circuit - Intermittent

    Yesterday while the car has a fuel cleaner in the tank, while I cycled the ignition a few times, it's still running like pooh. I've also noticed that the car seems to be running quite rich. You can smell the half burnt fuel and even the onboard computer is recording terrible mileage.

    So I removed the intake manifold yesterday, replaced the G247 sensor. Made no change. I've ordered a new HPFP to replace the one with the bad N276.

    Am I on the right track? Is there something I'm missing or not thinking about?

    Any input would be great.

    Thanks

    Roy

  2. #2
    Veteran Member Four Rings R&Cs4's Avatar
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    Have you logged the fuel pressure from your injectors?

    Dolphin S4 Cabriolet
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    IG @dinuzzohyeah

  3. #3
    Senior Member Two Rings MugelloB7RS4's Avatar
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    Quote Originally Posted by R&Cs4 View Post
    Have you logged the fuel pressure from your injectors?
    Negative.

    I can, Is that possible through a VagCOM?

  4. #4
    Senior Member Two Rings
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    Sounds eerily like the 614 relays...

    see: http://www.audizine.com/forum/showth...-can-t-resolve

    Just picked up a pair from Europa Parts for ~$12 each while my ECU/engine were out of the car. Cheap/easy replacement once you get the ECU box open!

  5. #5
    Veteran Member Four Rings R&Cs4's Avatar
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    Quote Originally Posted by MugelloB7RS4 View Post
    Negative.

    I can, Is that possible through a VagCOM?
    It is. Info from another thread:
    Fuel trim data is a good place to start if you think your injectors might be clogged/clogging. Look at VCDS measuring block 032, which shows your long term fuel trims at idle and load. Short term fuel trim can be monitored in block 033.

    A clogged fuel injector will inhibit optimal fueling in the motor. The ECU will see this lack of fuel over time using the O2 sensors and call for a permanent fuel trim correction. Looking at measuring block 032, a clogged fuel injector will cause a positive number to show up in the Partial field(Partial means at load). In my case it was showing between +5% and +6%. While these numbers are in spec, we really don't want to be running lean. Lean conditions are bad for engine performance and safety.

    If you have positive long term fuel trim at load(block 032 Partial field), you can be fairly certain your fuel injectors are not flowing optimally if your car meets the following conditions:
    Good O2 sensors - Bad O2 sensors can cause inaccurate fuel trim readings
    Good fuel pressure on both banks - Check measuring blocks 103, 106, 140
    No vacuum leaks - Check the Idle field in block 032, it should be slightly negative in a good condition.
    Normal short term fuel trims - Your short term fuel trims need to be within +/- 10%.

    Dolphin S4 Cabriolet
    Misano RS4

    IG @dinuzzohyeah

  6. #6
    Senior Member Three Rings ven0m's Avatar
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    Quote Originally Posted by R&Cs4 View Post
    It is. Info from another thread:
    Fuel trim data is a good place to start if you think your injectors might be clogged/clogging. Look at VCDS measuring block 032, which shows your long term fuel trims at idle and load. Short term fuel trim can be monitored in block 033.

    A clogged fuel injector will inhibit optimal fueling in the motor. The ECU will see this lack of fuel over time using the O2 sensors and call for a permanent fuel trim correction. Looking at measuring block 032, a clogged fuel injector will cause a positive number to show up in the Partial field(Partial means at load). In my case it was showing between +5% and +6%. While these numbers are in spec, we really don't want to be running lean. Lean conditions are bad for engine performance and safety.

    If you have positive long term fuel trim at load(block 032 Partial field), you can be fairly certain your fuel injectors are not flowing optimally if your car meets the following conditions:
    Good O2 sensors - Bad O2 sensors can cause inaccurate fuel trim readings
    Good fuel pressure on both banks - Check measuring blocks 103, 106, 140
    No vacuum leaks - Check the Idle field in block 032, it should be slightly negative in a good condition.
    Normal short term fuel trims - Your short term fuel trims need to be within +/- 10%.
    We all have this guide stickied. I got it bookmarked aswell
    Jeremy Clarkson: "So when you were saying that it wont slide, what you meant was, I cant slide it.
    James May: "Yes."

  7. #7
    Senior Member Two Rings MugelloB7RS4's Avatar
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    This is why I love Audizine. Thank you guys for the valuable info.

    I don't disagree that the injectors aren't prestine. I actually have a full set that I will be installing. I'm going to try a new high pressure pump tomorrow.

    The car also badly needs a carbon clean. So if the pump doesn't fix it, I'm going to just dig right in and do injectors, plugs and clean the carbon.

    I really do need to be paying attention more to the fuel trims. The kicker for me was that when I would add a fuel system cleaner it seemed to work great. That could have totally been a placebo effect.

  8. #8
    Senior Member Two Rings MugelloB7RS4's Avatar
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    Hey guys, so this morning I put in the new high pressure pump with zero change. The car still runs the same, and the car still has the same N276 Open circuit fault. I looked at the wiring at the connector and back as far as I could see and nothing stood out.

    So then I took R&Cs4's recommendation about looking at some vag-com data.






    Do those fuel pressures seem odd? It looks like the high pressure value is the same as the low pressure side. That would explain some of the poor running, but why do I smell so much fuel if it's got low fuel pressure? Also another thing I just noticed is that it seems like the high pressure pumps weren't ticking, as if they both weren't pumping.

    Does that happen when one pump faults? Is it in some type of safe mode?

    I'm a bit lost guys

  9. #9
    Registered Member One Ring
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    Quote Originally Posted by MugelloB7RS4 View Post
    Hey guys, so this morning I put in the new high pressure pump with zero change. The car still runs the same, and the car still has the same N276 Open circuit fault. I looked at the wiring at the connector and back as far as I could see and nothing stood out.

    So then I took R&Cs4's recommendation about looking at some vag-com data.






    Do those fuel pressures seem odd? It looks like the high pressure value is the same as the low pressure side. That would explain some of the poor running, but why do I smell so much fuel if it's got low fuel pressure? Also another thing I just noticed is that it seems like the high pressure pumps weren't ticking, as if they both weren't pumping.

    Does that happen when one pump faults? Is it in some type of safe mode?

    I'm a bit lost guys
    yes seems like you have an electric problem there,actual rail pressure should follow specified pressure

  10. #10
    Senior Member Two Rings MugelloB7RS4's Avatar
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    Does the system default to anything when there is a pump open fault? Could my issue be just the pump open or is there other issues?

  11. #11
    Senior Member Two Rings MugelloB7RS4's Avatar
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    okay, so it looks like once the car sets fault for one of the high pressure solenoids it goes into a limp mode which in my case seemed to default to the solenoids in the high pressure pump staying open this making no high pressure.

    I must not have been properly clearing the codes because I went out this morning and cleared them properly and now they haven't come back. Good news and bad news. Good news is that hopefully that pump fixed the fault with the N276 valve moving forward but the car still ran like a pile of pooh.

    Since I planed on changing plugs, injectors, and doing a carbon clean anyway, my old school mentality told me to check the condition of the plugs to see how they were running. Well they were all pretty black. So I swapped them out and the car seemed to run pretty well right away. I didn't get to test it out much, but the fuel pressure values all seemed normal, it seemed to be back up and running well. It also made me think that when I would put fuel system cleaner in the tank, it was actually cleaning slightly the spark plugs which would let them run well for the next bit until they got fouled again. Good to know and a sort of easy fix. I don't understand why it wasn't registering any misfires though. It was running noticeably bad. I still am unsure of the root cause, I don't know if the fuel pump was acting up causing it to run rich and fouling the plugs. I didn't think it had been that long since I changed them, but maybe it was. It seems to be running okay now. I'm waiting on a couple more tools and then I'm going to tackle the carbon clean and injectors so we will see how it runs between now and then.

  12. #12
    Senior Member Three Rings ven0m's Avatar
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    Keep us posted and thanks for the update!

    There is an updated solenoid available from JHM if you want to renew the HPFP's while you're at the injectors and carbon tackle.
    Jeremy Clarkson: "So when you were saying that it wont slide, what you meant was, I cant slide it.
    James May: "Yes."

  13. #13
    Senior Member Two Rings MugelloB7RS4's Avatar
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    Quote Originally Posted by ven0m View Post
    Keep us posted and thanks for the update!

    There is an updated solenoid available from JHM if you want to renew the HPFP's while you're at the injectors and carbon tackle.
    They have just the solenoid that's updated? I have replaced both pumps a couple times because of solenoids faults and would be nice to get an updated piece.


    So I drove the car this morning to work and everything went well. I was quite easy on it as I busted a nipple off the upper rad hose and I had to JB weld it and I didn't want to put undo stress on the system. New upper rad hose is ordered and once installed I will give it a good romping.

    So end fix seems to be High pressure fuel sensor and High pressure fuel pump to get rid of the codes, but it was the spark plugs that fixed the drivability. Moral of the story is always check the basics.

  14. #14
    Senior Member Three Rings ven0m's Avatar
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    Here is just the upgrade kit
    https://jhmotorsports.com/shop/catal...html?cPath=0_1

    And here are the completed pumps with upgrade kit installed
    https://jhmotorsports.com/shop/catal...html?cPath=0_1
    Jeremy Clarkson: "So when you were saying that it wont slide, what you meant was, I cant slide it.
    James May: "Yes."

  15. #15
    Senior Member Two Rings MugelloB7RS4's Avatar
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    Those kits don't have an upgraded solenoid, they have upgraded internals which help to increase fuel pressure thus not working the N276 valve as hard and in theory makes them last longer. As of now, I'm not sure there's any places that will allow you to just buy the solenoid on their own.

  16. #16
    Senior Member Three Rings ven0m's Avatar
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    Ah sorry then I misunderstood which part was the solenoid. Sorry!
    Jeremy Clarkson: "So when you were saying that it wont slide, what you meant was, I cant slide it.
    James May: "Yes."

  17. #17
    Senior Member Two Rings MugelloB7RS4's Avatar
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    Oh no worries man, it's still something to think about. I've gone though a few pumps and if the upgraded internals can help, it might be worth it.

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