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New ECU Fitted... do I need a computer engineer now?

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  • New ECU Fitted... do I need a computer engineer now?

    Well... I'm not out of the woods yet... But I can see the lights...

    The short version: I have a 2nd hand ECU kit fitted... ECU, BCM, Airbag Bit, Stalks and Ignition (Thanks Restorer... worked a treat!!)

    I turn the key... the car works again, although as badly as it did before I tried to fix it... but that is another story...

    Anyway... it goes for about three minutes, I think I read you need to leave it running to allow the ECU to re-remember it's settings... It was idling rough so when it konked out I let it be.

    But now... it won't fire up, I get electrics, I get central locking, I get little pictures on the dash, but it won't fire up (getting a distinctive knock or click but no turnover).


    Do I now need to find someone with Opcomm/VauxComm to programme the 'new' ECU?

    The clock I have reads 78,000 miles and the defunct ECU had about 94,000 but I'd rather be honest and upfront.

    There was no VIN or code with this new ECU so will that be a problem or are there ways and means??

    As ever all help appreciated and taken on board.



  • #2
    It sounds to me as if your main problem, is a flat battery.
    All of the items that you mention (central locking, little pics on the dash etc) draw very little current, whereas the main 'current hungry' item is the starter motor.
    The knock/click that you here is probably the starter solenoid, but the motor itself is not receiving enough power.
    A quick check for this, is to switch 'ON' the headlights and then attempt a start - if the lights go out or go very dim, it is almost certainly the battery that is flat, but it is worth checking/cleaning the main battery to starter terminals, not forgetting the earth connections.
    It could well be that the battery only requires charging rather than replacing.

    More serious problems that may cause the knock/click include a faulty starter motor, or even a seized engine.
    (If you can turn the engine by hand, it isn't seized)

    Start with the simple things first (battery and connections) It is very likely that it has become flat due to repeated starting and very little running.



    • #3
      Walksall I think you are spot on the the money...

      I had had the battery on charge overnight at least twice but the battery drained within the day.... now that I had it all put back together it had started the first time which proves it's mechanically sound, but wouldn't spark to life after...

      I got a friend with some jump leads and hey presto we have life and a rumbling engine.

      Thank you all for your input in these matters. I will give a full account of my exploits with pictures, not to show you guys who have helped me out along the way, but for the guys and gals that will come across this situation in the future, which is what brings people like me to forums like this.

      So, off to buy a battery. Will let you know if all is well in the Corsa D world later.



      • #4
        So... I have a new battery fitted... it starts and even runs... BUT

        It seems to be limping along in first gear, maybe not more than 2,000 RPM

        I know I have seen that you may need to "re-train" the gears/ratios with OpCom or Tech 2. Is that imperartive or did I read somewhere that it will re-learn if I take the car out and about and run it in?

        Also, while I have your attention, it reads 78,000 miles on the clock (coz it's a swapped over ECU) where as the engine has actually done about 96,000 miles...

        Can I up the number on OpCom ??

        Thanking you for your time again peeps.


        • #5
          Are there any lights showing on the instrument panel (engine management etc) ?

          It would pay to check for fault codes, make a note of any codes and clear (delete) them.
          Give the car a run and re read the codes - any codes there now will be new ones and probably point to your problem.

          I've never changed the mileage reading, but would imagine that it needs Tech 2 to do so, otherwise every back street car dealer would be 'adjusting' the mileage that the proverbial 'Only one careful lady owner' had covered.



          • #6
            Thanks again for your input Walksall.

            I have the car up on stilts where the first mechanic (who trashed the ECU) is reconnecting some pipework...

            I will look to see the christmas tree effect when I get it going next... and report back.

            As for the milage thing I thought I saw in passing one time that people can move the clock forwards, but need special tools to make it go backward... I just want to make it right of course.

            Any other thoughts welcome people.



            • #7
              I think some cars can communicate between the mileage recorded in the speedo head and the ecu ,and adjust , but this may be based on chassis number . Even if Corsas have this facility, deleting the chassis number may have disabled this . I think there may be specialists on line who can adjust mileages. Imagine if the replacement ecu had a really high mileage recorded.

              I dont know if more simple readers can wind forward. If they can I presume it must stop at max 99999 digits otherwise you could wind beyond zero and start again moving forward.

              If you cant get it adjusted beware when you sell the car, privately or to a dealer. . I would put a sticker on the speedo with the correct adjustment and ensure the buyer signs some form of paperwork that you keep that makes clear the correct mileage,and that he is aware. Otherwise you might find yourself being blamed for the discrepancy if a subsequent owner complains, and the real villain denies any knowledge. Keep all mots's with historic mileages as well. I dont know what happens when the mot records a lower mileage than previous years . Does the mot computer flag it up in some way?


              • #8
                That's an excellent point about MoTs Bugman.
                With that in mind, I would suggest that you contact VOSA (Vehicle and Operator Standards Agency) and ask their advice on the subject, if they reply by mail or email, I think that it would be a good idea to keep a copy of their reply (just in case their advice on the matter changes at a later date)

                We didn't have this sort of problem when: In days of old, when knights were bold and speedos were mechanical.....



                • #9
                  I will indeed check this out if for no other reason when it goes for it's MOT and the previous readings were 90,000 and escalating and now it is circa 76,000.

                  As for reading the ECU and the speedo head Bugman, the whole lot has been taken from a similar Corsa and transplanted in to my 'dead' Corsa... so all of those units, the ECU, Clocks, BCM, Airbag Module, the wiper/stalk unit and the door lock/Ignition/transponder unit have been installed.

                  Hence my original question, before the ethics and liabilities kicked in... "Do I need the ECU re-programmed to learn the gears/ratios"

                  Does anyone know if I need to have that done at all... the car is still up on axle stands waiting for my ace mechanic to reconnect some cooling pipes.

                  All input welcomed and encouraged.


                  • #10
                    I too seem to vaguely recall that the ecu can 'learn' settings. I think this may apply to the 'fly by wire' electronic throttle. But if the same applies to gear /ratio changing I dont know (Presumably its an easytronic gearbox) .

                    Last edited by Bugman; 09-11-2019, 04:29 PM. Reason: deleted DIY guide to 'clocking' mechanical speedos - self moderation


                    • #11
                      Well... just to let anyone know who has been following, and/or comes late to the party where we're at...

                      The car has been re-plumbed... it has a new battery... it drives... (like a 50cc trials bike!!!... gonna start a new thread for help now... follow me>>>)

                      Thanks for your help to date people...