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Thread: 2007 4.2L FSI w/ rough idle P0102 P010C Low MAF

  1. #21
    Verified VCDS User stone4779's Avatar
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    small update:

    The new MMI control circuit board came in early this morning at 10AM!

    I installed it after work, and now have restored function of the MMI. Navigation, radio, CD changer, setup menus the works. The telephone doesnt work, but I am guessing that is referring to an actual in-car phone? May need to look into a way to add bluetooth after I get the engine and trans codes sorted out.

    So although the car still doesnt drive perfect, at least I can stop worrying about spending time/money getting a working screen.

    Small victories!

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  3. #22
    Verified VCDS User stone4779's Avatar
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    I confirmed again today that if I plug in the driver's side high pressure fuel regulator (N276) the 15A fuse pops.

    If I unplug N276, and then install a new 15A fuse..clear the codes, and then the fuse doesnt pop.

    So I am pretty sure that driver's side high pressure fuel regulator valve is toast. We have been planning to get it soon.

  4. #23
    Verified VCDS User stone4779's Avatar
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    I was finally able to make time to get the 24 hour erWin subscription to download everything they had on Audi Q7s. Lots of juicy info in there. Although I am still trying to find out how I can use my multimeter to test all the sensors one by one. Like info on what the proper resistance should be for each sensor or device. I tested the resistance of the pins on the connector on the chassis side of the driver's side HPFR. (Not the pins on the actual HPFR)

    I made a diagram to define which pins I am referring to in order to be more clear.



    Ignition key OFF

    32.4 Ohms across the two pins A & B
    Pin A to ground = 26.5 Ohms
    Pin A to Pos(+) battery terminal = 0.00 Ohms no resistance at all
    Pin B to ground = 5.84 Ohms
    Pin B to Pos(+) = 0.00 Ohms

    Now I wanted to check voltage. Still with the ignition key OFF.

    Pin A to ground = no voltage (1 mA or so)
    Pin A to Pos(+) = 12.26v
    Pin B to ground = no voltage (1 mA or so)
    Pin B to Pos(+) = 12.26v
    Pin A to Pin B = 0.3 mV so basically nothing

    Now with the Ignition key ON:

    Pin A to ground = 2.45v
    Pin B to ground = 1.79v

    It was difficult to get in there to measure the resistance across the two pins on the actual N276 HPFR. I may just pull it off to check the condition of the camshaft follower so that if it does need to be replaced, when we order the new N276 HPFR for the driver's side...we can go ahead and get the camshaft follower as well. and of course a new o-ring seal.
    Last edited by stone4779; 03-24-2019 at 03:41 PM.

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  6. #24
    Verified VCDS User stone4779's Avatar
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    I do have a lot of wiring diagrams from erWin...I need to map all the sensors that are throwing codes for short to ground and for low signal..and find the common points to look for failure. I will post up what I find out.

  7. #25
    Verified VCDS User stone4779's Avatar
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    Small note: I have been referring to "N276"..which is wrong. My generic scanner says N276, but it is in fact I believe N402.

    I measured the resistance across the two pins on each HPFR and the passenger side (which hasnt been throwing codes) is within spec (1.5Ω), but the driver's side is only 0.5Ω.

    Audi spec for N402 (and N290) is between 1.5Ω and 11Ω +/- 0.5Ω @ 68F.

    Guess we are replacing N402 (driver's side) HPFR. I need to inspect the cam follower still in order to make sure we do/dont need a new one.

  8. #26
    Verified VCDS User stone4779's Avatar
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    I will be posting up some wiring diagrams I got from erWin. Here is a diagram showing fuse S13 (the one the blows when I plug in the driver's side high pressure fuel regulator connector)

    It also shows N402(driver HPFR) wiring diagram



    I would like to test things while I wait for the new fuel pump. Any tips on a good approach to verifying the wiring and other sensors on fuse S13 are good to go would be highly appreciated. It would suck to buy a brand new fuel pump only to mess it up!

    Thanks!

  9. #27
    Benevolent Dictator Uwe's Avatar
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    OK, so fuse S13 feeds five different current tracks, only one of which (194) is shown here.

    Now the only thing on the other side of N402 is the ECU, which actuates N402 by closing "closing a switch" to ground inside the ECU. Since the other side of N402 has +12 on it, this is called a "low side switch".

    If S13 blows when N402 is plugged in, and doesn't blow when N402 isn't plugged, in, then N402 almost certainly has to be bad (resistance too low, pulling too much current through S13 when the ECU tries to turn it on). But you measured 34 ohms? I'm confused.

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

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  11. #28
    NostraJackAss Jack@European_Parts's Avatar
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    If S13 blows when N402 is plugged in, and doesn't blow when N402 isn't plugged, in, then N402 almost certainly has to be bad (resistance too low, pulling too much current through S13 when the ECU tries to turn it on). But you measured 34 ohms? I'm confused.

    -Uwe-
    Or wiring to ECU is possibly shorted direct to other track/ground..........


    123 load lights!

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  13. #29
    Verified VCDS User stone4779's Avatar
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    Quote Originally Posted by Uwe View Post
    OK, so fuse S13 feeds five different current tracks, only one of which (194) is shown here.

    Now the only thing on the other side of N402 is the ECU, which actuates N402 by closing "closing a switch" to ground inside the ECU. Since the other side of N402 has +12 on it, this is called a "low side switch".

    If S13 blows when N402 is plugged in, and doesn't blow when N402 isn't plugged, in, then N402 almost certainly has to be bad (resistance too low, pulling too much current through S13 when the ECU tries to turn it on). But you measured 34 ohms? I'm confused.

    -Uwe-
    First, thanks for the reply Uwe!

    and yes I did measure 32.4 Ohms across the two pins on the N402 connector on the CHASSIS side, not on the actual N402 itself.

    The two pins on N402 itself, came to 0.5 Ohms. Out of spec.


    So the connector on the chassis side should test as an open circuit? because pins A to B on mine do have about 32 Ohms of resistance. Just trying to clarify.

    I will be at work all day, but this evening I want to set aside at least an hour or two for me to test the wiring as best I can.

    thanks again!

  14. #30
    Verified VCDS User stone4779's Avatar
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    Quote Originally Posted by Jack@European_Parts View Post
    Or wiring to ECU is possibly shorted direct to other track/ground..........


    123 load lights!

    Thanks for your reply as well, Jack!

    Yes I was afraid of that lol. That is a great video, thanks! I am gearing to go then! I already have the pages in the service manual handy that show removal of the ECM so that I can gain access to the pins on the ECM connector.

    So I am guessing that I need to test the resistance of the wire coming from pin 35 of the T60 connector on the ECM, to the wire that is brown w/ a black stripe on the connector going to N402?

    and then conduct a load test on it as well?

    I do not have a probe light at all (I know I know lol.. how have I survived thus far in life? lol) lots of squinting at the screen on the multimeter lmao xD

    I will see if I can get a probe light with 55W bulb to do the load test

    thanks again Uwe and Jack. I really really appreciate having outside input to confirm or deny my thinking here and to have a little bit of direction. I am excited to be learning how to do all this properly.

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