Idle speed adjustment GS 1015
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Thread: Idle speed adjustment GS 1015

  1. #1
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    Default Idle speed adjustment GS 1015

    Hello

    Now that the GS carb has been rekitted, I’m in the process of setting the idle. (Everything on the car is good - valves, points, spark, timing, fuel, air cleaner... all fine)

    There are two running adjustment screws - idling air and volume (fuel mixture)

    I’ve got it just about right in terms of running nicely with good power on tap, however, despite some very fine adjustments of a quarter turn here, a quarter turn there, these few problems/symptoms persist:

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    - idle mostly sits at about 950 but feels lumpy
    - engine sometimes cuts out when pulling up at the lights
    - idle can sometimes go up to about 1200 after blipping the throttle, and sit there a while before eventually settling down
    - Idle goes up if coasting downhill in neutral (is the vacuum advance doing this?) but settles back down when slowing down to a halt, by which time the engine might have already cut out.
    - exhaust smells more fumey than usual (even for a GS)
    - exhaust gurgling (but not backfiring) on the overrun

    Can anyone suggest which way to adjust it next? Too rich? Too lean? Too much air?

    Note this car doesn’t have an EGR valve.

    Thanks anyone
    Cheers

  2. #2
    Too many posts! JohnW's Avatar
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    Is the carbie butterfly shaft worn?
    JohnW

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    Umm donít think so John, at the carby shop they pressure tested it and was all good.

    Iím thinking could it be a vacuum leak in the manifold.. maybe buried under the tinwork somewhere I remember Lance saying the 1015s were particularly notorious/difficult to get to idle ďfrom newĒ.

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    Got it! All sorted, running like a sewing machine now. Feels sporty and zippy like it should. What a car, love my GS.

    Thank you JohnW, the only one who bothered to offered a suggestion, hats off to you sir.. gracious folk the Renault people.
    JohnW and CXVingtCinq like this.

  5. #5
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    Quote Originally Posted by graham66 View Post
    Got it! All sorted, running like a sewing machine now. Feels sporty and zippy like it should. What a car, love my GS.

    Thank you JohnW, the only one who bothered to offered a suggestion, hats off to you sir.. gracious folk the Renault people.

    How did you fix it Graham?

  6. #6
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    Quote Originally Posted by dspec View Post
    How did you fix it Graham?
    I was wondering too!
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

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    I found it idling the smoothest (the best I could get it) when the air was less and the mixture (fuel volume) was more. I figured this must mean it’s sucking air elsewhere, likely a vacuum leak. Not sure if they can ever be fully eliminated in a GS, but what did make a difference was the carby mounts, after reaching normal operating temp, had loosened up and needed to be retourqed down again. The difference after doing this was immediately noticeable, enough to get it to idle smoothly enough to then tinker with the mixture and get it right.

    Of course it helps that everything else is in good tune.... timing, spark, dwell etc.

  8. #8
    Too many posts! JohnW's Avatar
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    Sounds as if you found and fixed the induction leak. If there were still one, I suspect it would take more than fiddling with the idle mixture screw to get it to behave.

    Hope you didn't overtighten the carby flange - these die-cast things warp easily.

    Excellent!
    graham66 likes this.
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  9. #9
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    I don't know much about these carbys yet but I understand something to watch for is the accelerator pump and possibly replacing the diaphragm in them, I have a 1220 and will be investigsting this when I get around to rebuilding the motor.

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