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Corsa b 1.0 12v engine missfire

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  • [Corsa B 1993-2000] Corsa b 1.0 12v engine missfire

    anyone ever had this kind of problem ive noticed when driving along or taking off you can feel a miss from the engine around 2000rpm anyone know what might cause this

    car has just been serviced new plugs oil airfilter oil filter im thinking its the throttle bodie or one of its sensors or am i wrong do these have a crank sensor or anything else i should look for.

    i need to mention the throttle cable is set to its last little groove where it can be adjusted for it to stay running ticking over idont think this has anything to do with it

  • #2
    Any sign of the engine management light when the engine misses? Be worth clearing any codes and re-checking to see what might be present.

    If all the basics are good then the usual issue with these is the airflow meter - you can disconnect it to check if the engine runs better without it, you'll get the EML & a code, but the ECU will run on a default setting which will show whether the AFM is the fault or if it's something else.

    Only ever use a genuine AFM on these as the cheapo versions are often problematical.
    1972 Viva restoration thread - http://www.thecorsa.co.uk/projects-b....html#post1534

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    • #3
      Check all the breather hoses, they perish with age and can split, drawing in too much air could cause the problem you mention

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      • #4
        sorry meant to ad no engine management light comes on when its missing i did plug in a obd scanner i have checked for faults both new and past none show up. So all good that way ive noticed to when i went out to start it from cold it doesnt like running to well very low idling and not a smooth idle

        from reading a few posts these suffer from these common faults so im going to replace a few just so i know there ok

        1. crankshaft sensor
        2. idle speed control valve
        3. airflow meter
        4. EGR valve

        i may try that disconnect the afm see if that help should i do it before or when engine is running

        i would prefer to buy an oem part at least i have peace of mind knowing its a genuine part and not a cheapo that work for 10mins

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        • #5
          Originally posted by Blackie View Post
          Check all the breather hoses, they perish with age and can split, drawing in too much air could cause the problem you mention
          i'll check all them hoses and pipes i do know they get gunked up and need cleaning out
          now you mention it i had the exhaust heat sheild off and noticed it was very black around where exhaust bolts to head am i right in thinking it needs a new manifold gasket as it is kinda noisy when ya first start it i may really go over it check everything im new to these 1.0 12v im usually a fan of the 1.2 8v's so all these new sensors and stuff are a bit mad to me

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          • #6
            Lol!! Yea I'm a fan of the old Vauxhall 8v's myself, loved the c20ne fitted to the Cavaliers!

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            • #7
              Originally posted by Blackie View Post
              Lol!! Yea I'm a fan of the old Vauxhall 8v's myself, loved the c20ne fitted to the Cavaliers!
              yes my first corsa was a 1.2 8v 96 iirc i swapped a guy a kenwood cd player and a amp for it was in a bit of a state but turned from rags to riches i fitted a 1.6 8v think the engine is called a 16sv bolted all the 1.2 stuff onto it gearbox and all was a animal

              in a fairly raw state no seats half the engine missing to some wasnt worth even looking at never mind fixing but i seen hope in the little red corsa

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              • #8
                The coil packs are a weak point on these engines they can break down under load

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                • #9
                  Originally posted by Coupe77 View Post
                  The coil packs are a weak point on these engines they can break down under load
                  but after 2000rpm its fine it pulls really well and drives fine well i think it does revs clean all the way out to 4500 5000rpm i'd expect it to keep misfiring through out when the engine is under load

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                  • #10
                    Any leak in the exhaust near the front end of the system can draw air back into the exhaust which will throw the Lambda sensor out - that could result in the Lambda system believing the exhaust gases are out of parameter and telling the ECU to adjust the air/fuel mix accordingly. So if there's signs of an exhaust leak fix that before messing with anything else.

                    The crank sensor triggers the fuel pump relay once it senses the engine turning, so if it fails the fuel simply cuts off. They don't tend to cause a miss at a certain rpm. Their usual trick is to start from cold then fail once they get warm. The heat expands the coil inside them which breaks continuity - when they cool down they work again.

                    It's worth giving the EGR are clean with carb cleaner, again, you can check by disconnecting the EGR and seeing it is makes any difference. So long as the EGR is free to close then disconnecting it simply disables it from affecting the engine.

                    The 12v & 16v engines aren't really any more complicated than the 8v engines in terms of sensors. The very early 8v engines had a Hall Effect distributor and no EGR, but otherwise they're all working on the same principles.
                    1972 Viva restoration thread - http://www.thecorsa.co.uk/projects-b....html#post1534

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                    • #11
                      Originally posted by Taurus View Post
                      Any leak in the exhaust near the front end of the system can draw air back into the exhaust which will throw the Lambda sensor out - that could result in the Lambda system believing the exhaust gases are out of parameter and telling the ECU to adjust the air/fuel mix accordingly. So if there's signs of an exhaust leak fix that before messing with anything else.

                      The crank sensor triggers the fuel pump relay once it senses the engine turning, so if it fails the fuel simply cuts off. They don't tend to cause a miss at a certain rpm. Their usual trick is to start from cold then fail once they get warm. The heat expands the coil inside them which breaks continuity - when they cool down they work again.

                      It's worth giving the EGR are clean with carb cleaner, again, you can check by disconnecting the EGR and seeing it is makes any difference. So long as the EGR is free to close then disconnecting it simply disables it from affecting the engine.

                      The 12v & 16v engines aren't really any more complicated than the 8v engines in terms of sensors. The very early 8v engines had a Hall Effect distributor and no EGR, but otherwise they're all working on the same principles.
                      i may get the manifold off and have a good looks for any breaks in the exhaust or cracks where it might leak its very black around where manifold eets the head so going to get a new gasket as i'd say that ones shot.

                      right so crank sensor hasnt anything really to do with it i can atleast tick that off as not been a culprit to this

                      im going to whip it off tommorow and give it a good clean i did have a spare one here a friend left but cant be found going to disconnect it tommorow and see if it behaves any better


                      ah i found the 8v easy to work on i dont know why they just seemed more basic im a bit odd like that lol been the first opel engine i ever messed with i got acustom to its behaviour

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                      • #12
                        right bit of an update to ad to my on going misery i disconnected the egr valve started car seemed to start easier and quicker and even idle from the flick of the key not its usual hard to start hold the revs up to get it to stay running and not conk out thought i had solved the missfire car drove as it should though ok clean this egr valve and maybe i'll be ok. Drove around 10mins pulled up to set of traffic lights car starts idling all low again started off on the journey revs creeping up to 2000rpm miss still there but pulled on so went home hoped out and car idled low around 900 but stayed running ok bit tappy but its a 3 pot disconnected air flow meter while running revs dropped even more i'd say around 750-700 rpm plugged that back in idle picked up not enough but stayed running i disconnected the idle control valve this little thing i think it thats its name


                        And its didnt do a thing stayed the same revs never dropped or climbed so tommorow this is getting taken off took apart and cleaned and contacts sanded inside found a tuorial on it see if this helps if not then a replacement one will be sourced

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                        • #13
                          As you state, there is a tutorial on this site for same

                          I do not recall correctly, but I thinkthe tutorial does not include removing the rubber boot on the Idle control valve (right in pic)

                          I did this once and as far as I can recall there is a contact in there too.

                          Be careful when removing the boot in order not to damage it.

                          There is a spring and small parts in there

                          Generally in the IDC, there are small delictae parts (look like the insides of a toy train)

                          I would take this apart over a clean dry basin or such like to avoid dropping and losing parts

                          If I also remember correctly you have to reset it when finished - dont quote me but think you can do this by winding the assembly all the way in or it can be done with OPCOM. Check that first though before taking it apart

                          EDIT: clean out the throttle body while you are there :-)
                          Last edited by zuluman; 26-11-2014, 11:19 AM.

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                          • #14
                            i'll only be cleaning the contacts inside to see if its any better and if that helps as thats the main part i think which has failed or stopped working the tutorial says
                            Before you start the car again, to stop the motor adjusting wrongly the ECU needs to be reset. To do this, disconnect the car battery negative terminal for an hour
                            im going out now to remove it and give it a clean and replace it after the hour

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                            • #15
                              Disconnecting the battery only resets the ECU on the older 8v engines. The later models, including the 1.0 12v engines need diagnostic kit to clear the ECU.
                              1972 Viva restoration thread - http://www.thecorsa.co.uk/projects-b....html#post1534

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