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Thread: Rev counter going up and down

  
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    Rev counter going up and down

    Hi all - Firstly i would like to say Hi all and introduce myself.

    I own a 1.6SXI 52 reg astra and i must say its not good Problem after problem

    Got a quick question for you experts..

    My car seems to want to drive its self... The rev counter goes up and down on its own.. I can be driving in second gear an take my foot of the accel then the rev counter will go up and down about a 3rd of a rev and u can feel it jolting in the car.. only way to stop this is to clutch down or accelerate.

    It sometimes when driving in say.. 3rd gear at about 2.000 rpm it might jolt just the once an the rev will go down.. It feels like someone has yanked on the car from the back, Makes u go forward in ur seat abit.

    I have replaced EGR as engine management was on & replaced the spark plugs

    any idea

    thank you

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    graeme647's Avatar
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    Strange, I would have said the throttle body needed cleaning if it was only when warm / stationary, never known it happen when moving though...

    Do you have cruise control? Maybe the fly by wire throttle has a problem if you do...
    N.b. any opinitons expressed above should be ignored and considered 'ramblings', under no circumstances should they be relied upon...

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    It does it worse when cold believe it or not.. (i have noticed aswell sometimes at lights you put ur foot on the rev to go as if u would normally and it struggles as if the rev is less responsive so i have to put my foot down abit more before setting off.

    The car is a Manual

    Thank you for the quick reply

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    I have this same problem and i would like to know too. Not sure to be worried or what.

    When i initially start the car only sometimes it will rev up and down about the same amount as yours, but mine has never done it when its in gear/moving.

    I do have cruise control.

    Is this the throttle body problem?

    and S0nix133 have you found out anything else about this problem? As i wouldnt mind fixing this before the snow comes in cos i cbf breaking down when the weather is aweful lol.

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    When im standing and out of gear it idles perfect... Its just sometimes when i drive the needle goes up and down a fraction and u can feal it in the car. feels like im messing with the accelerator. if i find anything i will tell you mate.

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    strange problem! could there be something wrong with your throttle positioning sensor? just a thought!
    *Irmscher Astra G Hatch,
    *2.2L 16v(Z22SE)
    *154.0BHP, 151.3 lbs ft torque...
    ...For now...

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    could it not be something to do with the cluch???

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    if its worse when cold - try replacing the coolant temp sensor

    it screws into the thermostat housing at the front left of the engine - where the top rad hose joins onto the head

    Would definitely clean the throttle body out too whilst ur at it if u havent already done so

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    Quote Originally Posted by SXI GUY View Post
    could it not be something to do with the cluch???
    Yeah I was just thinkin that myself, sounds very clutchy...

    where in the pedal travel is your bite point, mines about 2/3rds of the way down to the floor which seems about normal...

    Anyway, sounds like the clutch is slipping (revs go up) then it catches and you get the jerk you mentioned...

    Try below (ripped from elsewhere)...
    STEP 1: Find a stretch of open road, or a long street with no traffic.
    STEP 2: Bring your car up to about 20-25 miles per hour
    STEP 3: Shift into 5th gear, or whatever the highest gear is that your car has. Yes, it's too soon to shift into high gear, but that's the point of the test--to stress the clutch.
    STEP 4: Press the gas firmly, as if you were accelerating onto a freeway.
    STEP 5: Observe! If the engine starts to rev free, as if it were in neutral, and/or your tachometer needle spins toward redline very quickly, your clutch is slipping.
    STEP 6: Observe! But if the car slowly accelerates, even if it staggers, bucks and strains, then the clutch is okay!
    N.b. any opinitons expressed above should be ignored and considered 'ramblings', under no circumstances should they be relied upon...

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    Quote Originally Posted by GeordieBandit View Post
    if its worse when cold - try replacing the coolant temp sensor

    it screws into the thermostat housing at the front left of the engine - where the top rad hose joins onto the head

    Would definitely clean the throttle body out too whilst ur at it if u havent already done so
    Dirty TB wouldnt do this unless it was well and truly gunked and the butterfly valve couldnt open at all, high revs means the valve's open nice and wide which means the gunk shouldnt affect it...

    Not a bad thing to do though, easy and only costs a bit of petrol / carb cleaner...

    Why do you say coolant temp sensor? If it was reading high temp when its actually cold the engine would stall when starting on a cold morning if it ever even started, if it was reading colder than it is then you would be getting over fuelling which wouldnt cause higher revs, it would cause the engine to bog down if anything...
    N.b. any opinitons expressed above should be ignored and considered 'ramblings', under no circumstances should they be relied upon...

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