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  1. #1
    mark
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    could installing a Saab thermotime switch affect..

    idle? Causing a surge? Help!

    I've researched archives on idle surge, didn't see anything.

    background with apologies for ignorance and length: Have a 528e. Had hot start issue years ago, "solved" by mechanic installing a Saab thermotime switch which I think caused the cold start valve to spray fuel for a longer period or in hotter temps. not sure.

    anyway, that did fix my hot start issue years ago but at that time it also created an idle surge issue. idle would surge. BUT, here's where it gets screwy. The idle only surged when I had a "kill switch" to my starter flicked in the "off" position (ie. no power to starter). Now what's this kill switch. Well, I had an old starter that would continuously "spin" in rain or cold weather (even if i turned ignition off and took key out!!), so my old mechanic installed a "kill" switch instead of giving me a new starter. cheaper and fixed thatproblem. if starter spun, i flicked the switch, killed the starter and tried er again until it worked.

    But after getting the Saab thermotime switch installed, my idle would surge badly if the "kill" switch was in the "off" position, but it would not surge at if the kill switch was in the "on" position.

    So for years I would drive it fine, car started in hot weather and I made sure to leave the kill switch in on position.

    Fast forward to today: My mechanic just installed a new starter, tuned it up, adjusted valves, clutch, etc. AND NOW IT SURGES CONSTANTLY when kill switch in "on" position. If kill switch in "off" position, idle doesn't surge, it just goes up to 2000 rpm and stays there. it is not driveable.

    I went to pick it up from him and it was surging like crazy. Somehow he didn't notice.

    Ideas??? thanks!!


  2. #2
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    Re: could installing a Saab thermotime switch affect..

    First, get rid of the kill switch. Now when you say it surges, are you describing the condition where idle oscillates between 6-700 RPM and 15-2000 RPM. This issue is indicative of a problem with the idle control valve or idle controller. First thing to do is remove the ICV and give it a thorough cleaning using carb cleaner. You should be able to simply spray it out. 9 times out of ten that solves the problem. If it doesn't then the problem is electrical. I'll post later on troubleshooting that part or you can search the archives on "ICV" or "idle controller".
    -----------------------------------------------------
    Richard O.
    1986 528e
    1989 325iX
    1998 328iC

  3. #3
    mark
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    yes on surge. big surge. 700 to 2000 rpm surge.


  4. #4
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    Re: yes on surge. big surge. 700 to 2000 rpm surge.

    Well try cleaning it. I won't get a chance to look at the schematics for the idle circuit until this evening.
    -----------------------------------------------------
    Richard O.
    1986 528e
    1989 325iX
    1998 328iC

  5. #5
    TJ
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    lol

    I doubt that it is because of the thermotime switch.

    The starter is connected directly to the battery though by a big fat cable, which leaves me wondering what exactly this kill switch is wired up to.

    I've had the starter stick on in my e30 a few times. Last time I just opened the hood and banged on it and it stopped.

  6. #6
    mark
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    fixed! ICV connection it was....


  7. #7
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    Glad to hear it.


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    Richard O.
    1986 528e
    1989 325iX
    1998 328iC

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