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Corsa B cold start problem

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  • [Corsa B 1993-2000] Corsa B cold start problem

    Have a Corsa b just under 100k with the 1.2 8v c12nz engine.
    Problem started a couple weeks back when cold, for rev below 1.5k it would loose power and act like it wants to stall. Previously it drove fine, power was consisted and started first time even when freezing cold.

    Roughly a week ago when starting from cold I would have to crank for a bit then it would start. There was a code for idle speed valve so cleaned out icv and checked to see if the motor works, and it did move in an out. Changed the CTS, for good measure. Cleaned throttle body with carb cleaner. Problem persist with map disconnected, and also throttle position disconnected. Had to crank for a while for it to start.

    Car sat for a couple days. When cranked, rev rises and falls a little up to ~200rpm, tries to kick in a few times and makes the 'stalling' type noises. Tested sparks within line light. Only had one so tested each one by one, all flashed up ok. Battery voltage 11.5-12v. It started but much harder than before.

    Took it for drive round the block. Fine when moving fast, above 2k rpm, no problem at all. Drove for a bit then cut out in the middle of the t junction, because I have to stop. Engine starter motor working with a fair bit of power, just didn't want to start, didn't even make the stalling noises and rev glued to zero. Tried to start for a bit, nothing and the battery started to flatten. Called up recovery and got the engine running, he jump started it but it was still v difficult.

    Got home left engine on to recharge the battery until the fan the kicked in. Turned off, started again much easier than before as engine was hot, started easily first time. Took it for a drive, round that same block ironically, also went up and down the dual carriageway. Did not notice anything unusual and power was like before the start of all these problems.

    No codes, only idle speed which wasn't relevant, and also the sensors I had disconnected.
    Left battery unplugged to clear all codes. Left it for a few days, really cold morning, engine didn't want to start again, no stalling noises and rev glued to zero didn't even twitch there. No new codes, just 12.

    Really stuck for ideas. To sum up: have changed ICV as it was the original fault code and CTS. Don't think its the throttle position or map sensor as problem persisted when they were disconnected. Clear fuel pump is file as engine runs fine when when hot, and there is power reaching the sparks as the tester did flash on all 4 plugs.

    And no, engine doesn't have a crank sensor, says so in hynes and also went down to check.

    Any suggestion appreciated?

  • #2
    I'd check the battery first. The voltage of a battery at rest ought to be about 12.5, yours is reading 11.5-12v which suggests a weak cell. The ignition system on those is quite power hungry, you can have enough juice in the battery to crank the engine, but cranking will drop battery voltage which disables the ignition system from working sufficiently well to fire a cold engine. I've seen this many times on Vauxhalls. Just because they crank over doesn't mean that the battery is holding voltage to power the ignition system as well.

    Also, an alternator won't recharge a flat battery. The old dynamos would, but alternators really only replace the starting charge used. You can jump start a car with a flat battery, drive 200 miles, and the battery will still be flat. You need to trickle charge it overnight to bring the charge back up to good condition.

    A car battery with the engine off ought to read 12.5-13v, with the engine running it ought to read 14v. You can get the battery checked to see if it is dropping voltage under load - ie when cranking, but it will usually kill a weak battery so some places don't like doing it.
    1972 Viva restoration thread -


    • #3
      Point taken, battery is out and on a trickle charger.

      But is it likely that that the battery is the root cause of my problem, hard to cold start and stalling/power problem when engine is cold at low revs?


      • #4
        the battery is the main power source for all the electrics in the engine bay and everything else. If the voltage starts dropping from a weak battery its going to affect everything else

        look at it this way the battery has to give the starter enough power to crank engine over/power to sensors/power to fuel pump/dash lights all these are a small drain so i would for peace of mind fit a new battery just to make sure you have plenty of power

        quick question when your turn on lights or heater does the engine speed drop or idle drop down


        • #5
          Not too sure about lights. But distinctly remember when the radiator fan came on rev always drops then goes back up again, but thought it was normal under load.

          Interesting though, as all my problems are happening when when engine is dead cold, and hasn't been driven for a couple days. It would be fine if I drove the night before even.
          Last edited by Lee; 05-12-2014, 09:35 AM. Reason: Though!


          • #6
            fan always does that idle drops as its using extra power.

            could well be battery as you say hasnt been driven for a couple of days and engine is left to go cold battery is ever so slightly dropping voltage when left idle over the days


            • #7
              Left it in charge for about 2 hours then tried again. Starter motor ran but nothing else. Left it on charge for about 10 hours voltage stable at 12.8v. Started runs, rev kick up the first time I tried then. After that nothing.

              Will leave it to charge for couple days.

              What should current reading be with engine off? Mine is 0.24A, could it be too high and was draining the battery only when I leave it long enough without a drive?


              • #8
                That does sound higher than it ought to be. Try pulling fuses one at a time until you find the circuit that's drawing the current.
                1972 Viva restoration thread -


                • #9
                  Charged battery up over night, with virgin media router adapter. Put the battery in, starter runs, engine now does rev up to >200 but doesn't start. Got a mate to come and jump start, still no cooky.

                  Was ready to call the scrappers. But for one last check took out the spark plugs. Totally sooted up and shiny. It was actually petrol on them as the shine evaporated. There was petrol fumes coming from the plug holes. Left the ht leads out and went to get new plugs. Think a combination of bad battery, faulty icv had resulted in many, many bad starts which sooted up the plugs. I distinctly remember checking them about three weeks ago.

                  Put everything back in, it then started with its own battery and ran really rough for about half an hour. I assume it was burning off all the easy start and carb cleaner I have sprayed down the intake. Huge plumes of smoke at the back.

                  When it cleared up took car for a drive, no problems. Drives sweet as a nut again, looks like iv got my 45 ponies back.

                  Decided to leave the battery unplugged, so it doesn't drain overnight. Cold started again, this time no problem starting. I turned off tried again, started. I turned off again, started but this time laboured for while then started and it idled really low. Took the icv out and piston appeared to be stuck in the out position, pushed it back in and installed. Started first time, Idle rev rocketed up then down on 1.2-1.4k for a bit then settled to 0.8-0.9k.

                  Hopefully when I come back to the car in the weekend it will still start, be it after fiddling with the icv.

                  But is it possible that I got two faulty ICVs in a row? The origin factory fitted did move, but was *really* stiff to push. The new one clearly does work as it dropped the rev when temp changed but got stuck in hot position. Or could it be dodgy temp sensor some where?


                  • #10
                    glad to here its starting again im sure the weekend it will fire up no problem again. now the check is to find where your battery drain is coming from. did you you buy the icv 2nd hand or new there not ment to be really stiff as you said new one is working as rev dropped. thats more the automatic choke turning off think they work when water reaches certain temp


                    • #11
                      When you fitted the ICV did you clean the throttle body port where it locates? Muck in there will cause the ICV to stick.

                      Have a look on ebay for Quicksilver Powertune, it's made for powerboat engines, but it's by far the best product I've found for cleaning crud out of throttle bodies.
                      1972 Viva restoration thread -


                      • #12
                        The icv was new from eurocarparts, will go there to see if i can get a replacement. I used Wynn's purple carb and injector cleaner, but I couldn't get my rag in the little hole to clean it properly. Now that you say, will be at it again with a toothbrush and rag on the end of a screwdriver.

                        I always have the engine off, but is it best to leave the engine running when:
                        1)Cleaning the just the injector body
                        2)Icv holes

                        Also how long would it take to remove the entire body and clean? Haynes makes everything look simple, but there's always that one bolt that won't come off!


                        • #13
                          should takke about half an hour to take the throttle bodie of the 1.2 there an spi engine so cleaning them is tricky as it sits dead in the middle of the throttle body


                          • #14
                            If you take the injector out make sure you have spare O ring as the old one usually won't go back into place. But there's no need to remove the injector to clean the ICV port. The Quicksilver stuff is much more effective than the Wynns.
                            1972 Viva restoration thread -


                            • #15
                              There's a thin plastic tube that goes from the back of the throttle body cover to the front of the injector body. Connect to the injector body with a little brown elbow. What is it? Elbow has snapped and its a bit sooted up.