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Thread: Srv

  1. #1
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    Srv

    Is it possible for the short runner valve and related to fail without setting a code?

    My scanner says that the SRV system is activating at 5200 rpm, but the feedback PID for it never moves from 50% at any rpm and the butt dyno says this car makes about 1/3 the torque of my 2 liter car until past 3500 rpm.



  2. #2
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    Quote Originally Posted by doublechaz View Post
    Is it possible for the short runner valve and related to fail without setting a code?

    My scanner says that the SRV system is activating at 5200 rpm, but the feedback PID for it never moves from 50% at any rpm and the butt dyno says this car makes about 1/3 the torque of my 2 liter car until past 3500 rpm.
    Have you checked to see if it’s actually open or closed?

    Can you move it manually?
    Thanks doublechaz thanked for this post

  3. #3
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    Haven't tried those things yet, but a visual and manual is coming. I have four other active project cars, so sometimes the planning and doing phases are a bit separated.

    If I had to guess I'd say that tiny flimsy plastic socket is broken and the vane is stuck at the 50% mark. I would've expected a code, though.

    The up side is, while I was in there, I reprogrammed my headlights to not stay on forever after I park, and activated the daytime running. I could not find a place to correct my speedo.

    This car was supposed to be a reliable daily while I catch up on some of the others.

  4. #4
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    Srv

    Quote Originally Posted by doublechaz View Post
    Haven't tried those things yet, but a visual and manual is coming. I have four other active project cars, so sometimes the planning and doing phases are a bit separated.

    If I had to guess I'd say that tiny flimsy plastic socket is broken and the vane is stuck at the 50% mark. I would've expected a code, though.

    The up side is, while I was in there, I reprogrammed my headlights to not stay on forever after I park, and activated the daytime running. I could not find a place to correct my speedo.

    This car was supposed to be a reliable daily while I catch up on some of the others.
    That was my first thought. The motor is moving, but the valves aren’t. That’s why it’s not throwing a code.

    I have no idea why they made the valves so rigid to turn.

  5. #5
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    The OBD rules keep getting more scrutiny and now they have to be set up so that it checks for an end stop for fully closed and fully open to make sure that valves are actually moving. In older days, if the solenoid or motor moved it could pass the test. What I am not sure of is when the rules tightened up. I know the Eagle version of the 5.7L meets the tighter requirement (2009+), but I don't know about the 3.5L for sure, but I think it's possible it was designed to the older standard. (in conclusion, I think you could be motor moves but disconnected from valves, or shaft broken part way)
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  6. #6
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    Sounds like I'm just on the cusp for when the better systems sensing went in. That is exactly the info I was looking for about if it could be failed and yet not throwing a code. I'll try to get in to it this weekend, but we are forecast to get our first skywater in about 250 days, so maybe not. Solid water no less. :/

  7. #7
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    That was dumb of me not to get this done sooner. Very easy to get to and service. I figured it would be behind and under a bunch of stuff that would involve breaking seals to gain access, etc. Not so, up top, front and center o-ring seal.

    The way it comes apart it's hard to be positive, but I'm pretty sure it was assembled with the pawl on the servo jambed under the socket on the valve so that everything was frozen in place at the high rpm setting. The valve moved freely by hand and didn't feel broken back in there where I can't see. The drive socket wasn't broken as I feared it would be (like with the HVAC recirc door). With a little care aligning the bits during assembly I can now track the PIDs with my scanner showing that it is working, and better than that, test driving has gone from about 70 ft lb of torque everywhere below 3500 rpm and then running as expected above that rpm to now having a torque curve that starts at about the converter stall speed. It still peaks up high like before, but it doesn't make me cry down low. It may even no longer be slower than my 2 liter NA Subaru.
    Last edited by doublechaz; 11-19-2020 at 12:44 AM.
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  8. #8
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    How freely did your valves move? Mine take a bit of force to move.


    Sent from my iPhone using Tapatalk

  9. #9
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    Not as easy as something that size would move if it was not touching anything, but pretty easy. If it had a round style toothpick attached to the socket you could move it that way, but if it was the smaller flat/square type toothpick it might break.

  10. #10
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    Quote Originally Posted by doublechaz View Post
    Not as easy as something that size would move if it was not touching anything, but pretty easy. If it had a round style toothpick attached to the socket you could move it that way, but if it was the smaller flat/square type toothpick it might break.
    Yeah, no. I have to use a screwdriver to turn it, and it creaks when I turn it.
    Which I’ve often wondered about, because you can feel a kick when it opens under load. So it’s probably resisting until it finally pops open.

  11. #11
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    Now that you have yours open you should be able to find where it is binding, but yeah, it should move with light hand pressure, no tools.

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