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Thread: Loss of Power/Limp mode?

  1. #1
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    Mech Loss of Power/Limp mode?

    Car has been in the shop all week getting the radiator replaced along with the timing belt, water pump etc. and had the valve cover gaskets and cam tensioner seals replaced. Pretty extensive work. I had a friend pick up my car due to me being out of town. I got back today and immediately wanted to check everything out and I am noticing a serious power loss. At first I thought maybe it is the Texas heat just cutting the power but I did the "redneck" ecu reset by unplugging the battery. After turning it back on and driving it, the power was back at the level I remember. After a few minutes it went back into what I would call limp mode. No check engine light. Want to run a scanner and see if there is any codes. Any suggestion on what it could be? Obviously it's going back to the shop to get it checked out but I was going to see if anyone had a similar experience and suggestions.

  2. #2
    Registered User lswing's Avatar
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    Hopefully just boost leak at hose or air box not seated right....mechanic, you used before and like, location?
    Ace/Edge TC - Tozo Trans - MTM TCU - REVO/ME7 tune - Wagner IC's w/ Venair Hoses - Aux Radiator delete - Hotchkis Sways - Hawk HPS Pads - Koni Sport Struts - Scroll KO4 Turbos - Devil's Own WM - 421whp/452wtq on Mustang Dyno - http://www.audirssix.com

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    Dubsquared in Arlington did all of the work. He said the car was kicking his butt. Haven't done to much work with them. Just an oil change no major work from them.
    tad disappointed missing some engine covers by the steering fluid container. and obviously the car isn't running right. Partially my fault for not being there to pick it up.

  4. #4
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    C5 RS6 ownership comes with VagCom ownership.

    One does not go without the other.

    This can be a slow car in extreme heat. Esp if its stock

  5. #5
    Registered User lswing's Avatar
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    Quote Originally Posted by DHall1 View Post
    C5 RS6 ownership comes with VagCom ownership.

    One does not go without the other.

    This can be a slow car in extreme heat. Esp if its stock
    Yep...post 6,000, hot damn!

    That scan should help get things started...
    Ace/Edge TC - Tozo Trans - MTM TCU - REVO/ME7 tune - Wagner IC's w/ Venair Hoses - Aux Radiator delete - Hotchkis Sways - Hawk HPS Pads - Koni Sport Struts - Scroll KO4 Turbos - Devil's Own WM - 421whp/452wtq on Mustang Dyno - http://www.audirssix.com

  6. #6
    Registered User ttboost's Avatar
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    Check to make sure your air box is seated properly. Make sure there are no boost leaks, especially to the wastegates. Does the car feel faster than it was, like more boost?
    2013 Audi S8

  7. #7
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    I will check the air box to see if it is set properly. It feels like it's under boosted not over boosted. When I step on it.. It's almost like it's out of breath.

  8. #8
    Registered User hahnmgh63's Avatar
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    I think what ttboost meant was when you did the reset, but before it went into limp mode again did it feel real powerful for a short time just before? This would be a sign of the car over boosting and going into limp mode. On the compressor side of each Turbo there is a vacuum/pressure hose (control signal) to the wastegates that if disconnected will cause the car to over boost. They are a stainless flexible line that go to a metal T behind the engine on top of the tranny and go to the N75 valve.
    2003 White RS6 2013 Midnight Blue S5
    2013 Daytona RS5 2x944 Turbo's 1974 911 w/'91 3.6ltr motor
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    Thanks for the clarification hahnmgh63. I really can't say forsure if it felt more powerful. It would drop a gear and go though like normal but while in limp mode it holds whatever gear I am in regardless of pedal position. What is the best way to go about checking the waste gates? From underneath or from above? I pulled the airbox and checked everything I could get my hands on. Nothing seemed a miss besides one green plug that sits by the coilpack wires. No clue what it is called exactly.

  10. #10
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    Imho ^^

    A complete waste of time without first running a scan and data log.



    Quote Originally Posted by DHall1 View Post
    C5 RS6 ownership comes with VagCom ownership.

    One does not go without the other.

    This can be a slow car in extreme heat. Esp if its stock
    Last edited by DHall1; July 28th, 2014 at 21:21.

  11. #11
    Registered User hahnmgh63's Avatar
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    As Dhall said, pretty tough to diagnose without a scan and not being there in person. If it's a Green wire with Yellow stripe right behind the drivers headlight then I think that is the one that connects to the lead for the A/C clutch.
    2003 White RS6 2013 Midnight Blue S5
    2013 Daytona RS5 2x944 Turbo's 1974 911 w/'91 3.6ltr motor
    Roy, WA

  12. #12
    Registered User MaxRS6's Avatar
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    Quote Originally Posted by DHall1 View Post
    Imho ^^

    A complete waste of time without first running a scan and data log.

    +Ummmphhh- Do a scan---report back..get answer
    Last edited by MaxRS6; July 29th, 2014 at 00:10.
    210K miles rolled

  13. #13
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    The air box wasn't seated correctly wasn't even on really. Anyways got the car detailed and it is up for sale 15500.00
    Replacing the front windshield and getting it inspected this week.
    Who wants it? Love the car but ready for something easier on the wallet.

  14. #14
    Registered User ttboost's Avatar
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    I like my chicken grilled.

    Bummer, another one bites the dust...
    2013 Audi S8

  15. #15
    Registered User hahnmgh63's Avatar
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    Throw out all of the details here. Mileage, Mx. See it just got the Timing Belt job. What else? Pics?
    2003 White RS6 2013 Midnight Blue S5
    2013 Daytona RS5 2x944 Turbo's 1974 911 w/'91 3.6ltr motor
    Roy, WA

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