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  1. #1
    Established Member Two Rings
    Join Date
    Jul 09 2008
    AZ Member #
    30699
    My Garage
    04 Acura MDX, 1999 Camaro Z28
    Location
    Greenville, SC

    The simplest things can have a big impact...

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    I read threads when I need a break from work, trying to learn from other peoples experiences as they toil over ten different things that could be causing today's 1.8T issue. I find it enjoyable...learning how to take your money pit and make it more fun to drive and more reliable.

    My R1 diverter valve ripped and since I didn't buy it, APR wouldn't warranty it. I don't like that they warranty the buyer and not the part...so I did not buy another R1 valve. I bought the 710n diverter valve and installed it in the "reversed" orientation because, after reading too much Audizine, that's what I thought I should do. On my APR 2+ tune, I could now only spike to 16-18 psi and then taper off to 9-10 psi by redline. Obviously something was wrong, but after checking for boost leaks, vacuum leaks, N75 functionality, wastegate actuation, diverter valve vacuum, throttle body relearn...nothing seemed wrong.

    Since nothing else seemed to be wrong, and since this was the most recent change to the car, I decided I would reinstall it in the factory "pull" orientation rather than the reversed "push" orientation...just to see. This is a brand new Kayser 710n diverter valve that holds vacuum. After this quick change, the low boost fluttering is gone and I'm hitting target boost pressure. Maybe the valve is faulty, but for now, I am choosing to leave the 710n valve in the factory orientation.

    It was a simple change with a huge effect. So I spent all that time chasing problems that weren't there, when the first thing I should have done was to check the part that I just changed. Lesson learned...again...

  2. #2
    Junior Member Two Rings MRB1019's Avatar
    Join Date
    Mar 09 2014
    AZ Member #
    152608
    My Garage
    Chevy Tahoe, 240SX, A4 Avant Quattro 1.8T
    Location
    Dallas, TX USA

    That was a good read man. Lesson learned... for sure.

  3. #3
    Veteran Member Four Rings eljay's Avatar
    Join Date
    Aug 13 2015
    AZ Member #
    348695
    Location
    NS

    Good point on troubleshooting steps and method.
    At the same time, you are saying that the factory orientation of the DV works better while, just like you, all I've read here about the DV orientation says that the reverse orientation is superior. So, the fundamental question is: why didn't the reverse orientation work for you? Perhaps some of the knowledgeable folks can chime in to explain why the evidence here does not support it and what else could have changed to produce these boost results.

  4. #4
    Veteran Member Four Rings diagnosticator's Avatar
    Join Date
    Aug 26 2005
    AZ Member #
    7741
    Location
    Seattle, WA

    It is not clear what the maximum boost specification is for your APR 2+ tune. When boost pressure "spikes" occur, that means the boost pressure overshoots the maximum setpoint pressure desired. Boost pressure spikes are to be avoided as much as possible since that is an uncontrolled excess amount of boost above the maximum boost setting setpoint, and pressure spikes increase stress on the turbo, and decrease boost pressure control response with increased time off setpoint.

    It is not possible for a diaphragm DV installed in the "reversed" orientation, to leak boost pressure as described. I am not going to explain here why this is the case, other than to say that the physics involved won't allow that to happen. Are you sure the DV was actually installed reversed the first time? Other than that, the Kayser DV is not the original Bosch "710", and the specific parameters of the properties used in the Kayser DV are not known, compared to the Bosch 710. The spring preload and rate may be higher or lower than the Bosch DV, and the diaphragm material is likely different. The reversed orientation is actually the original orientation used by Audi, but was changed due to complaints of noisy operation in the original orientation. Confusing, I know. The APR R1 DV has a reputation of not working right in either orientation. However there is nothing to explain that situation contrary to the physical dynamics relevant for either orientation controlling the function of the DV, with the same reasons the 710N DV cannot leak boost in the reversed orientation.
    Last edited by diagnosticator; 03-11-2016 at 11:29 PM.
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