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Thread: Is it possible to swap different generation Vr4 ECU's

  1. #1
    mitsiboyblue's Avatar

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    Angry Is it possible to swap different generation Vr4 ECU's

    HI there guys, needing some advise with some diagnosis I've 8th generation vr4 auto on my drive that has had a faulty battery for a length time (not sure for just how long) which was repeatedly jump started in the past.
    It was blowing the dedicated 20amp engine control relay circuit fuse under the bonnet but diagnosis has confirmed a faulty ecu so I've taken one off from an earlier generation Vr4 manual (the only one i have to be used as a test tool) which has got the engine running but i have a constant misfire and flooding of the plug on the front bank nearest to gearbox. There is also a good spark

    Part No. VR4 AUTO MD362895
    swapped with
    Part No. VR4 Manual MD340288
    Just want to know could the misfire and flooding be anything to do with the maps being different on the two models or do I have another fault? Any advise would be greatly appreciated

    Also where can I get the ecu repaired or does anyone have a spare I can purchase ?
    Cheers Dave

  2. #2
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    I've had different engine ecus fitted without any issue so an injector stuck open may be your issue at the moment
    Ask a simple question, never receive an answer these days

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    mitsiboyblue's Avatar

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    Thanks Peter for a speedy response,
    After a while you start to question your own abilities, I will check this out next

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    mitsiboyblue's Avatar

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    Can anyone help with an ecu or a trusted repair service

  5. #5
    Confused's Avatar

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    ECUs are essentially able to be swapped without issues.

    As Peter said, it's probably an injector failed open. You will not need anyone to look at your ECU.

  6. #6
    mitsiboyblue's Avatar

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    Yes its going to be my next point of diagnosi.
    But I'm looking to get the other ecu repaired because I think it's the best one for remapping

  7. #7
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    Think this is terminal just carried out compression check and got big fat zero on No.3 front bank. Cylinder had load of fuel in it.
    Any ideas anyone?

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  8. #8
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    no compression can only be due to a stuck open valve or very badly worn piston rings (or a hole in the piston). If there is fuel in the cylinder, its more likely to be a valve stuck open.

    Take the cam cover off the front bank and have a look.

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  9. #9
    Davezj's Avatar

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    I second the valve cover removal.
    You should be able to see a valve stuck open. By the valve spring remaining compressed when the cam lobe is not pressing on it and the bottom of the cam is not touching the top of the valve spring.
    The issue is the 6a13tt engine is an interference fit engine meaning if a value is stuck open it will get hit by the piston. And the valve will be bent, which will cause a stuck valve to be propperley stuck and not fixable. It will have to be replaced which is a head off job.
    You could take the plenum chamber off which will allow you to see the back of all the inlet valves and it should be obvious if their are any stuck open.


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  10. #10
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    You could be right Dave but I think there is some clearance between the cylinder and valve? If the valve is only slightly open it could be okay? If it is fully open then just a bent valve is probably the best case scenario.....

  11. #11
    Davezj's Avatar

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    I think their is only a few mm clearance between the piston top and the valve which is why they needed to put relief cuts in the top of the piston.
    So he could be lucky.


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    ok guys, endoscoped down the plug hole, piston good no signs of damage. Removed inlet manifold inspected all backs of inlet valves all good. i Turned each cylinder in turn to tdc and filled with diesel fuel checking for leaking/damaged valves but unsurprisingly all were ok?
    So built back up again. Scratching my head now.... No headgasket symptoms, coolant perfect.
    Engine oil does smell of fuel and possibly diluted/contaminated
    I returned back to the cylinder in question No.3 geatbox end removed spark plug, TDC and filled cylinder with 75/80 gearoil. Yes i know... 'What the Hell you doing'. Took the valve out of my compression tester tool and made an adaptor to my air line then pressurized the cylinder. It forced the oil past the ring set into the sump over about 10mins. and repeated it 3 times. then carried out another compression test and guess what.... 176psi. Conclusion.... there was absolutely no oil on the rings, all washed away because of the injector fault (leaking)
    Cleaned out injector with little home made device and plenty of carb cleaner and refitted.
    Restarted engine was still running on 5 probably due to all the oil but No.6 kicked in and running ok now.
    Exhaust smoking its nuts off at the moment but guessing it all the partially burnt and unburnt fuel in there.
    Thanks guys, Thanks for the advice it helped me a lot.

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