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    Will another ECU fix this?

    So I might go and look at a cheapish '94 Subaru Impreza sportswagon to buy as a runaround and maybe use for khanacross etc. The owner has told me that he bought a low mileage later model imported motor from a local business who told him it would be a straight swap and no new ECU needed.

    He fitted it and it runs fine for a while and then loses all power (limp home mode?) Turning ignition off and then restarting fixes it for a while. He took it to the local "performance workshop" (the owner of which fucked me around many years ago when he first opened his doors) who charged him a few hundred bucks, told him it was a few loose connections, all fixed, but the car is still doing the same shit.

    So, if I can buy this for about $1k (also has newish G'box and replaced CVs) is it fixable by the addition of an aftermarket ECU? How hard is it to diagnose this modern jiggerypokery? Can you get a program/interface for your laptop and how much $$? I may be able to get a relatively rustfree RWD Celica and/or corolla to fix up for free, and I'm comfortable with that technology, but realistically I could be driving and playing with this a lot quicker and I'm guessing making it go faster/stop better could be achieved on a budget by buying 2nd hand WRX stuff from blokes that are upgrading.

    Help please!

    Mick

    #2
    Try a secondhand ECU, should be able to get one pretty cheaply from someone wrecking one.

    If you have to resort to an aftermarket ECU, then the whole thing is simply not worth your time IMHO.

    Comment


      #3
      But if I wanted to make it go faster (turbo, cams, whatever) wouldn't I need to get an aftermarket ECU anyway?

      Mick

      Comment


        #4
        Paging JZK25.

        Come in Al.
        Cheers, Richard

        MX83 Cressida Grande - 1JZ-GTE Twin Turbo JZX81 Motor, Fr Suspension in, tailshaft made & installed, bigger fuel pump in, zorst, wiring, fmic done (thanks jzk25) BA rotors R33 Calipers Now REGISTERED going well
        '92 & '94 TF Holden Rodeo 2.8 TurboDiesel 4WDs - Daily Driver regular breaker/backup ute
        MS85 Crown Super Sedan - Farm Car - Running 3rd 4M - Future project
        '66 Jaguar E-Type 4.2 Manual Coupe
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        - Long Term Jobs

        Comment


          #5
          scan it for fault codes first and see why it is going in limp mode?

          could be something real simple such as a sensor fault.

          Comment


            #6
            If you want to make it go faster, put a WRX engine and factory ECU into it.

            Comment


              #7
              What engine did it have in it and what is in it now. Pics, model codes etc. Can't help without info.
              David Fraser - Automotive Historian!

              Originally posted by bigmuz
              You can't polish a turd but you can put 600hp in it and laugh your fucking arse off coming past someone sideways at Powercruise.

              Comment


                #8
                Originally posted by JZK25 View Post
                What engine did it have in it and what is in it now. Pics, model codes etc. Can't help without info.
                Will go and look at it tommorrow and try to get all that info.

                Mick

                Comment


                  #9
                  Okay, went and had a look this arvo. I got the vin no and build date (3/94) Couldn't find the engine number (was dark and no idea where to look) He reckons it's got the same model engine in it, just low mileage from an importer. He fitted it himself and I reckon he's probably fucked up a few connections for a start. Starts and runs okay, although it bogs down completely if you punch the accelerator hard when it's cold. I found that on idle when you push the brake pedal there's a slight hesitation in the revs so there's a vacuum leak or some issue there.

                  I'm about to go away for a few days camping here So will think about it then. It's basically this for maybe $1k + sorting out versus getting an old celica or corolla for free and building a car. (Although I could always hold off and maybe find something else.) If I still think I want it and it hasn't sold while I'm away I'll pay to get a permit for it and take it for a drive. He seems pretty keen to sell and not many people are spending money on this town at the moment.

                  Mick

                  Comment


                    #10
                    Sounds like it had an EJ18 in it and he has fitted an EJ20 or 22. EJ18 has a hitachi ecu that has no cam sensor or knock sensor and non sequential injection, it's the microtech of subaru ecu's. They don't handle capacity changes well.

                    For $1k you have plenty left over to sort it out. Engine code(EJ20/22/25/16/18 etc) is cast into the block just behind the alternator. Find that out and take some photos of the engine.
                    David Fraser - Automotive Historian!

                    Originally posted by bigmuz
                    You can't polish a turd but you can put 600hp in it and laugh your fucking arse off coming past someone sideways at Powercruise.

                    Comment


                      #11
                      Engine currently in it is an EJ20, according to his ebay ad. So this car would have come with an EJ18 originally? Pictures attached. Just wondering about other major components like gearbox and diffs, if I were to upgrade later down the track to a WRX motor, would these be up to it, or are the WRX ones much beefier? I know the brakes would need upgrading (I notice it only has rear drums) Thanks for the help, BTW

                      Mick

                      Comment


                        #12
                        If you put an EJ20T in it you would just buy a halfcut that comes with turbo gearbox, diff and brakes.

                        If the thing won't run properly at all and never has since the EJ20 was fitted then it will be because the crank pulley was not changed over from the EJ18. Hitachi, Unisia JECS and Nippondenso ecu's all use there own version of crank(and cam) pulleys with different trigger patterns. The hitachi ecu does not use the cam sensor but has an extra tooth on the crank to indicate TDC. The engine can start but will never run properly.

                        FInd out the whole story on the car.
                        David Fraser - Automotive Historian!

                        Originally posted by bigmuz
                        You can't polish a turd but you can put 600hp in it and laugh your fucking arse off coming past someone sideways at Powercruise.

                        Comment


                          #13
                          Originally posted by JZK25 View Post
                          .........If the thing won't run properly at all and never has since the EJ20 was fitted then it will be because the crank pulley was not changed over from the EJ18. Hitachi, Unisia JECS and Nippondenso ecu's all use there own version of crank(and cam) pulleys with different trigger patterns. The hitachi ecu does not use the cam sensor but has an extra tooth on the crank to indicate TDC. The engine can start but will never run properly.

                          FInd out the whole story on the car.
                          Thanks, very helpful information. I'll try to get the full story on the conversion.

                          Mick

                          Comment


                            #14
                            Just spoke to the bloke again, he's a bit of a numpty. Seems he did the swap himself with some "mechanic" mates. Thinks it was an EJ18 in it originally. When he did the swap they decided to swap the intake manifold so there were no dramas with the wiring. Is there anyway of telling what motor was in there originally from any of the codes on the plates under the bonnet? If it was an EJ18 in there and they've swapped in the 20 but kept the manifold, then what's the easiest way to fix it? Will swapping in an ECU from a 20 (and fixing the vacuum leaks) fix it?

                            It wouldn't surprise me if it's got major leaks on the inlet manifold, it would explain the bogging down when you punch the accelerator hard, as well as the hesitation on idle when hitting the brakes.

                            Mick

                            On edit: Thinking about it, I'm probably going to need an EJ20 intake manifold too, if the reason they swapped it was because of the connections not being the same.

                            Comment


                              #15
                              Swapping the manifold is the right thing to do, you need to check the crank pulley has a H stamped into it. If it is the original EJ20 pulley it will be for a UJ ecu which is missing one tooth.

                              It will run fine on the EJ18 ecu, I'd just put an aftermarket pressure reg on and bump the fuel pressure up if it is short on throttle pump. It is airmass metered so gives no fuck for engine size(to a point).
                              David Fraser - Automotive Historian!

                              Originally posted by bigmuz
                              You can't polish a turd but you can put 600hp in it and laugh your fucking arse off coming past someone sideways at Powercruise.

                              Comment

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