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rich tickover

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  • [Corsa B 1993-2000] rich tickover

    Hi everybody please could sombody help me .I have just finished my dads corsa b 1.4 16v ecotec
    we have rebuilt the engine and i want to mot it but cant because at idle i am sure it is running rich the engine starts first time every time but once it comes of the cold start it starts to flutter a bit and if i dip the throttle it somtimes stalls and it is a bit hessitant on pulling away.I have changed the map sensor and crank sensor to no avail i also have opcom and there are no fault codes or eml light but on the measuring blocks the rpm is reading 900 to 975 at idle but the rev counter is reading 750rpm i think the rev counter is right so i think the ecu is getting a wrong signal causing the rich idle any help would be appreciated many thanks.

  • #2
    Welcome to the Forum.

    Are you sure that the temperature sensor is connected correctly? - If you need to replace the temp sensor, I would suggest that you buy a genuine one, as some of the aftermarket ones are rubbish.



    • #3
      If it's hesitant pulling away then I suspect it's not running rich. A rich mix will cause a lumpy idle, poor hot starting, but it will pull like a train on throttle because the engine can burn the rich mix on acceleration.

      The fact that it's hesitant and starts to flutter once it's off cold start suggests an air leak. You won't notice it so much from cold due to the rich mix hiding the symptoms. I'd check all your vacuum pipes, intake and throttle body mountings.

      The rpm indicated by Opcom will be more accurate than the tachometer.

      The other thing of course is timing, if that's out then you'll get similar symptoms, so if there's no sign of an air leak double check the timing.
      1972 Viva restoration thread -


      • #4
        Thanks for replying on the opcom the temperature did rise and fall inline with the dashboard temperature gauge .I will change the temperature sensor with a genuine one thanks for your help.


        • #5
          Thank you for your help.I will check all the manifold joints for air leeks and the throttle body the other thing is the engine does pull like a train once it picks up on the opcom measuring blocks the timing is between 3 and 5 degrees at idle. I am going to check the intake system for leaks thank you for your advice.


          • #6
            I think Taurus meant check not just the ignition timing but the valve timing (crank, cams, belt). As he said, if this is slightly out it will run rough.