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Thread: Leaking injector O-rings

  1. #1
    Registered User V8weight's Avatar
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    Leaking injector O-rings

    I've been chasing some issues with my car for a while, where there was an intermittent sudden drop in specified load under boost or moderate throttle. The car would suddenly drop specified boost and close the throttle valve to 50% without reason. I finally found a trend in my logs where the MAF g/s would start to see-saw when the throttle cut occurred, and I also found that the knock voltage was a bit high on two cylinders. Here it is: I had two injectors that were leaking out of their o-rings, causing an almost untraceable vacuum leak.

    Here you can see the engine harness disconnected and the fuel rail removed:

    Here you can see the injector inlets on the manifold. The film is a tell tale sign that both air and gas were sneaking by.


    Here's the injectors that were leaking, as seen by the film above the O-rings:


    And here's a shot of the fuel rail.

    The car runs great now, no more partial throttle uncertainty, the car is consistent in the way it reacts to throttle input now, and so far no more throttle cut!
    Pat - Eisenmann race exhaust, Catless downpipes, KW V3's, H-Sport sways, 034 Control arms, Apikol diff mount, Sterns motor mounts, Forge dv's, Stainless brake lines, Venair hoses, Sportec vent mod, Euro tails, Viper Tuned ecu/tcu, DPE S20's 19x9.5, 275/30/19's

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    Registered User DonS's Avatar
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    Congratulations. Your deductive reasoning from the data seems better than my dealer mechanic...

  3. #3
    Registered User V8weight's Avatar
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    Quote Originally Posted by DonS View Post
    Congratulations. Your deductive reasoning from the data seems better than my dealer mechanic...
    Speaking of dealer mechanics, if they would have replaced these O-rings as the manual specifies when they did my after run coolant pump, this thread wouldn't be happening right now.
    Pat - Eisenmann race exhaust, Catless downpipes, KW V3's, H-Sport sways, 034 Control arms, Apikol diff mount, Sterns motor mounts, Forge dv's, Stainless brake lines, Venair hoses, Sportec vent mod, Euro tails, Viper Tuned ecu/tcu, DPE S20's 19x9.5, 275/30/19's

  4. #4
    Registered User MaxRS6's Avatar
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    Nice pics and info- Congrats on finding the issue!
    210K miles rolled

  5. #5
    Registered User ben916's Avatar
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    this forum keeps getting better and better!
    SOLD - 03 RS6 Avus (905355)
    Current - 03 Toyota Tacoma 4x4 double cab - the YETI, lifted, winched, snorkeled, lockered, skidded, geared

  6. #6
    Registered User JSRS6's Avatar
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    So that's what was causing the one bank to drop and the other to not in the graph, huh? I thought that looked weird.
    Avus RS 6, RNS-E/BT/RVC, Eurocharged/MTM, SuperSports, PSS9/Hotchkis, SS Lines/EBC Reds, FMU/BMC, Sportec vents, 007's, 9500ci, Black Optics/Headlights/Trim/Rims, CC; coming soon: stage 3 snow meth

  7. #7
    Registered User V8weight's Avatar
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    Quote Originally Posted by JSRS6 View Post
    So that's what was causing the one bank to drop and the other to not in the graph, huh? I thought that looked weird.
    No, that actually has to do with sampling rates. Like I said, under closed loop, the lambda voltages are in a constant wave swinging from 0-.8 volts about 10 times a second. When I kicked the car down and it started to go into open loop, the bank one voltages happened to be at 0, while bank 2 was in mid stroke. They both got the message at the same time, and moved from their respective voltage up into the .8's. It just has to do with bank 1 being sampled before bank 2, and the associated lag in data.
    Pat - Eisenmann race exhaust, Catless downpipes, KW V3's, H-Sport sways, 034 Control arms, Apikol diff mount, Sterns motor mounts, Forge dv's, Stainless brake lines, Venair hoses, Sportec vent mod, Euro tails, Viper Tuned ecu/tcu, DPE S20's 19x9.5, 275/30/19's

  8. #8
    Registered User JSRS6's Avatar
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    If you don't learn something new everyday, you are doing something wrong. Thanks.
    Avus RS 6, RNS-E/BT/RVC, Eurocharged/MTM, SuperSports, PSS9/Hotchkis, SS Lines/EBC Reds, FMU/BMC, Sportec vents, 007's, 9500ci, Black Optics/Headlights/Trim/Rims, CC; coming soon: stage 3 snow meth

  9. #9
    Registered User V8weight's Avatar
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    Quote Originally Posted by JSRS6 View Post
    If you don't learn something new everyday, you are doing something wrong. Thanks.
    Same here, I know I've been chasing this issue for quite a while, and have done hundreds of data logs and found most of them to have no relevant data in relation to the issue. As I learn more, I look back at those old logs that I've discounted, and suddenly there's discrepancies popping out of the data everywhere, I just wasn't looking for it. I was going to tell you that you were looking too far into the graphs, but when I thought about it, it's actually an attribute. Had I looked a but deeper, I could have figured this out months ago.

    Alright, I'm outta here, off to a bachelor party, Cheers.
    Pat - Eisenmann race exhaust, Catless downpipes, KW V3's, H-Sport sways, 034 Control arms, Apikol diff mount, Sterns motor mounts, Forge dv's, Stainless brake lines, Venair hoses, Sportec vent mod, Euro tails, Viper Tuned ecu/tcu, DPE S20's 19x9.5, 275/30/19's

  10. #10
    Registered User V8weight's Avatar
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    Still running strong today, I think I finally have this monkey off my back!
    Pat - Eisenmann race exhaust, Catless downpipes, KW V3's, H-Sport sways, 034 Control arms, Apikol diff mount, Sterns motor mounts, Forge dv's, Stainless brake lines, Venair hoses, Sportec vent mod, Euro tails, Viper Tuned ecu/tcu, DPE S20's 19x9.5, 275/30/19's

  11. #11
    Registered User JSRS6's Avatar
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    Awesome Pat. Great to hear. I got the wrong t-clamps in the mail, they are sending me the right size. They sent 3" min dia. Instead of 3" max. Oh well, I retested the sealed intercoolers and they are solid. Can't wait to install them.
    Avus RS 6, RNS-E/BT/RVC, Eurocharged/MTM, SuperSports, PSS9/Hotchkis, SS Lines/EBC Reds, FMU/BMC, Sportec vents, 007's, 9500ci, Black Optics/Headlights/Trim/Rims, CC; coming soon: stage 3 snow meth

  12. #12
    Registered User 4everRS's Avatar
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    This is good news Pat. How did you figure to check the injectors? It wasn't by chance on a Porsche forum was it?
    Quote Originally Posted by V8weight View Post
    Still running strong today, I think I finally have this monkey off my back!
    Avus Silver RS6 - Viper Stage 2 ECU/TCU - Water/Meth Injection - Frozen Rotors - Hbars - clear corners - Hella smoked tails - gutted precats

  13. #13
    Registered User V8weight's Avatar
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    Quote Originally Posted by 4everRS View Post
    This is good news Pat. How did you figure to check the injectors? It wasn't by chance on a Porsche forum was it?
    Porsche forum?? Basically the data was telling me that I had unmetered air entering bank 1, and more specifically, cylinders 2 and 3. My first thought was intake gaskets were the only thing that have a leak isolated to single cylinders. As I proceeded remove the air cleaner and inspect the intake, the film surrounding those two injectors was immediately evident. I replaced all 16 o-rings for about $34, so all in all a cheap repair. P.s., this was the cause of the silliness that you felt while test driving my car a Cars and Cafe.
    Pat - Eisenmann race exhaust, Catless downpipes, KW V3's, H-Sport sways, 034 Control arms, Apikol diff mount, Sterns motor mounts, Forge dv's, Stainless brake lines, Venair hoses, Sportec vent mod, Euro tails, Viper Tuned ecu/tcu, DPE S20's 19x9.5, 275/30/19's

  14. #14
    Registered User 4everRS's Avatar
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    I know you've been studying up on the P cars so I thought maybe you've seen P car owners that have dealt with this.
    Avus Silver RS6 - Viper Stage 2 ECU/TCU - Water/Meth Injection - Frozen Rotors - Hbars - clear corners - Hella smoked tails - gutted precats

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