Results 1 to 12 of 12

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

  1. #1
    mitsiboyblue's Avatar

    Offline
     
    Name
    Dave
    Join Date
    Jun 2011
    Last Online
    31-07-2021
    Posts
    301
    Country
    United Kingdom
    Location
    St. Helens,
    Car
    Legnum VR4 M/T
     

    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
    peter thomson's Avatar

    Offline
     
    Name
    peter
    Join Date
    Oct 2005
    Last Online
    05-01-2022
    Posts
    7,675
    Country
    Scotland
    Location
    Back O'Bennachi
    Car
    Jeep SRT8
     
    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

  3. #3
    mitsiboyblue's Avatar

    Offline
     
    Name
    Dave
    Join Date
    Jun 2011
    Last Online
    31-07-2021
    Posts
    301
    Country
    United Kingdom
    Location
    St. Helens,
    Car
    Legnum VR4 M/T
     
    Thanks Peter for a speedy response,
    After a while you start to question your own abilities, I will check this out next

  4. #4
    mitsiboyblue's Avatar

    Offline
     
    Name
    Dave
    Join Date
    Jun 2011
    Last Online
    31-07-2021
    Posts
    301
    Country
    United Kingdom
    Location
    St. Helens,
    Car
    Legnum VR4 M/T
     
    Can anyone help with an ecu or a trusted repair service

  5. #5
    Confused's Avatar

    Offline
     
    Name
    Garry
    Join Date
    Apr 2005
    Last Online
    Today
    Membership ID
    714
    Posts
    3,536
    Country
    United Kingdom
    Location
    Notts
    Car
    Legnum VR-4
    My Garage
    Visit
     
    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

    Offline
     
    Name
    Dave
    Join Date
    Jun 2011
    Last Online
    31-07-2021
    Posts
    301
    Country
    United Kingdom
    Location
    St. Helens,
    Car
    Legnum VR4 M/T
     
    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
    mitsiboyblue's Avatar

    Offline
     
    Name
    Dave
    Join Date
    Jun 2011
    Last Online
    31-07-2021
    Posts
    301
    Country
    United Kingdom
    Location
    St. Helens,
    Car
    Legnum VR4 M/T
     
    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?

    Sent from my SM-G930F using Tapatalk

  8. #8
    TAR's Avatar

    Offline
     
    Name
    Tim
    Join Date
    Apr 2006
    Last Online
    Yesterday
    Membership ID
    346
    Posts
    3,887
    Country
    United Kingdom
    Location
    Aylesbury
    Car
    '97 Legnum
    My Garage
    Visit
     
    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.

    '97 Manual Legnum in silver with some subtle mods

    My first VR4 - '97 Legnum Dark Green & mean ...it was love at first sight - now sold

  9. #9
    Davezj's Avatar

    Offline
     
    Name
    Dave
    Join Date
    Jan 2006
    Last Online
    09-01-2024
    Membership ID
    255
    Posts
    16,245
    Country
    England
    Location
    Manchester
    Car
    VR-4
    My Garage
    Visit
     
    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.


    Sent from my MI 5s using Tapatalk

    Bye for Now!

  10. #10
    Nick Mann's Avatar

    Offline
     
    Name
    Nick
    Join Date
    Sep 2003
    Last Online
    17-03-2024
    Membership ID
    17
    Posts
    24,895
    Country
    United Kingdom
    Location
    Redditch
    Car
    Legnum type-S
    My Garage
    Visit
     
    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

    Offline
     
    Name
    Dave
    Join Date
    Jan 2006
    Last Online
    09-01-2024
    Membership ID
    255
    Posts
    16,245
    Country
    England
    Location
    Manchester
    Car
    VR-4
    My Garage
    Visit
     
    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.


    Sent from my MI 5s using Tapatalk

  12. #12
    mitsiboyblue's Avatar

    Offline
     
    Name
    Dave
    Join Date
    Jun 2011
    Last Online
    31-07-2021
    Posts
    301
    Country
    United Kingdom
    Location
    St. Helens,
    Car
    Legnum VR4 M/T
     
    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.

    Sent from my SM-G930F using Tapatalk

Similar Threads

  1. When did you buy your first 8th Generation VR-4 ?
    By KiwiTT in forum General / Questions
    Replies: 13
    Last Post: 26-03-2011, 09:51 PM
  2. Gen-8 or Generation 8
    By VR4WGN in forum General / Questions
    Replies: 3
    Last Post: 30-04-2010, 11:03 PM
  3. Generation 7 front Foglights
    By Tapsell123 in forum UK Parts for Sale / Wanted
    Replies: 0
    Last Post: 12-02-2010, 10:29 PM
  4. Rear discs on 7th generation (E84A)?
    By kitefighter in forum Wheels, Tyres & Brakes
    Replies: 5
    Last Post: 21-05-2007, 11:08 PM
  5. next generation of fighting four-wheelers
    By d3x in forum General Chat
    Replies: 0
    Last Post: 20-09-2005, 04:57 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •