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Thread: 1998 1.6 16v Ecotec - Revs rise and fall when warm

  
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    1998 1.6 16v Ecotec - Revs rise and fall when warm

    Hi all
    First post so apologies for wrong forum, misreading rules etc.

    I have a beloved and rather pants 1998 astra mk3.

    Usual malarky of management light coming on. EGR valve indicated as cause so disconnected it.
    Car has run fine for months without EGR connected (though of course management light is still on).
    Last couple of months a new problem has occurred.
    Once engine is warm (half hour or so) the car will start to rev itself at idle (or when clutch is dipped, e.g. braking to stop). This doesn't seem to affect the running of the car and its done stacks of miles since problem first reared its head.

    However, its 1) doing my nut revving at the lights, and 2) scaring the missus who is currently learning to drive in it, so I need to sort it.

    The EGR valve is at the back, rh side of the engine, not sure if that helps id the exact model I have.

    I don't think the revs are connected to the EGR as it was disconnected for some time before this issue occurred (plus plugging it back in again makes no diff).

    Where do I start? I trawled forums but got caught up in throttle bodies, icvs etc. So thought best to find out what model engine I have so I can start cleaning/replacing bits.

    Any pointers gratefully received

    M.

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    definately sounds like the throttle bodys clogged and sticking open, take it off and give it a clean, whilst your at it you may as well clean the idle control valve

    hth
    MK5 1.7 CDTI OWNER AND AN ESTABLISHED MEMBER OF THE DARK SIDE!

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    had the same problem on mine, cleaned the throttle body and that sorted it.

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    Cool, thanks for the swift replies. Will have a crack at cleaning them both and let y'all know results.

    Forgot to mention that the revving actually rises up to 2000+ revs then drops back to 1100 before pulsing again, and only once the engine is warm and I've toodled around for a bit.

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    Curses.... Looked at the Throttle Body pdf with its "should be similar for other engines" quote; went out and bought carb cleaner etc etc.
    Opened bonnet and it seems I have the X16XEL engine which doesn't seem to be all that similar.

    Anyone got a piccy or text guide to attacking the throttle body on this model engine. I trawled forum and net and can't find one.
    (Haynes manual is in post but have the urge to rip engine to bits tonight...)

    M.

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    No sign of Haynes manual. Too cold to carrying on staring at the engine. Lost T30 into bay while molesting the EGR valve. Not a good day.

    Been digging in engine, can see 4 (T20?) bolts that seem to secure throttle body, on top facing front of car (buried under all sorts). The air intake comes up underneath but isn't secured by jubiliee or one of those squeezy clips but some kind of band with no obvious way of releasing.
    In a guide somewhere I saw 4 pipes going into a throttle body, two of which carried coolant. Can't find any trace of those on my one. Guess they are lurking underneath somewhere?

    Has anyone created a guide, or can give some pointers? Or at least able to tell me if the Haynes manual I've pinned my hopes on will actually cover how to get the throttle body off to clean it.

    Help!
    M.

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    Gave up on the throttle body. Lived with revs for months.

    took car in for MOT, obviously failed for emissions and idle test.
    turned out to be a perished hose. New hose for a few quid, and car is golden again.
    Still going strong. Bought it new front tyres as a reward.

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