Results 1 to 14 of 14

Thread: S14a misfiring at idle after manual swap

  1. #1
    Guest
    Join Date
    Feb 2019
    Location
    Edinburgh
    Posts
    9
    Rides
    0

    S14a misfiring at idle after manual swap

    Hi guys looking to pick your brains . I just carried out a manual swap on my 97 s14a. Now I managed to source a manual ecu with nats delete. I removed the old auto box with the wiring loom attached that runs behind the fuse box at the engine bay , the starter and alternator loom attached . Now I fitted the manual box with the manual starter loom and box loom . The issue I have is the car misfires at idle and takes ages to start , just cranks . I’ve noticed that I’m not getting any reverse lights but the loom was changed to manual . The manual ecu provided kept flashing the engine Managment light . So I re fitted my auto ecu with the manual loom attached . The misfire is still present but when driving it feels fine but when I come to junction/ traffic lights and the car comes to idle it misfires and feels like it’s about to cut out. Have you had any similar issues . I noticed the loom i fitted never had the solenoid connector for the solenoid that sits above the alternator below inlet manifold . So I took that from the old wiring loom and fitted but made no difference. My heads in a pickle with it. Has anyone had any similar issues or know where to begin.

  2. #2
    Now with 400bhp....
    Join Date
    Aug 2007
    Location
    South west
    Posts
    36,381
    Rides
    1
    Thought most people just kept the auto loom and ecu when doing the swap. Have you attached all of the grounds correctly on the new loom?
    1998 Nissan 200sx s14a , 2000 std 5 speed with nismo supercoppermix clutch bn6 Sapphire Blue

  3. #3
    Guest
    Join Date
    Feb 2019
    Location
    Edinburgh
    Posts
    9
    Rides
    0
    Hi Chris , thanks for the reply . Someone posted on a page that they had a s14a manual ecu with nats delete and the starter/gearbox loom so I thought I’d get away with just taken the old loom out and swapping the ecu over but has left me in a mess now as it idles with a very heavy misfire and feels like it’s going to cut out . Yeah all earths are good . Have you had any experience with the swap? I’m thinking if I re attach my old loom and splice the auto starter loom into the manual box this will be ok . Found a few posts with what to do regards the reverse switch. Do you know if I can run this without the auto transmission ecu but keep the original engine ecu (auto) and splice the loom ? Cheers , Mark

  4. #4
    Now with 400bhp....
    Join Date
    Aug 2007
    Location
    South west
    Posts
    36,381
    Rides
    1
    I’ve never done the swap unfortunately mate so can’t really be of much help. Did you replace the coil pack igniter and loom with the new loom or retain your own?
    1998 Nissan 200sx s14a , 2000 std 5 speed with nismo supercoppermix clutch bn6 Sapphire Blue

  5. #5
    Guest
    Join Date
    Feb 2019
    Location
    Edinburgh
    Posts
    9
    Rides
    0
    Ah no worries mate , I kept the original coils and igniter . Could find anything that claimed to having to swap them . The car is fine when driving in gear just at idle runs very poor , like on 3cylinders. The engine light doesn’t flash indicating a fault on the original ecu either . Thinking it could be something to do with signal from neutral position switch but unsure , this is my first s body so learning on the job ��

  6. #6
    Guest surewire's Avatar
    Join Date
    Mar 2016
    Posts
    36
    Rides
    0

    S14a misfiring at idle after manual swap

    Some auto to manual swap will have issues with the auto TPS. Swapping to a manual TPS might solve the problem.

    Have you already unplug the A/T control unit?
    Last edited by surewire; 28-07-2019 at 17:50.

  7. #7
    Guest
    Join Date
    Feb 2019
    Location
    Edinburgh
    Posts
    9
    Rides
    0
    Hi, thanks for the reply . Yeah the auto transmission control unit is disconnected ( the control unit that sits where the clutch pedal would be ) if I run the original engine ecu(auto) or the manual engine ecu ( nats deleted to run ) the car misfires on idle and when taken up the revs , but if driving on the road it’s fine , it’s only noticeable when coming to a stop and allowing the car to idle. By TPS do you mean throttle position sensor ? I’ve noticed my throttle has two connectors going into it , I imagine one may be kick down but not 100% sure. Cheers , Mark

  8. #8
    Guest surewire's Avatar
    Join Date
    Mar 2016
    Posts
    36
    Rides
    0
    Yes mate TPS is the throttle position sensor. Auto TPS have two connectors gray & brown and manual TPS have one brown connector.

    Basically auto idles higher than manual. After the swap I would think that your idle goes lower than the specs.

    What is your RPM at idle? It should be 800 +- 50 for SR20DE/DET.

    Try to slightly adjust/rotate your TPS to achieve the right idle RPM.

    Here is a youtube video about the TPS, most nissan in that era use the same TPS. Or you might have to replace to manual TPS.

    Good luck cheers!

    https://youtu.be/_EFvu76LQO0

  9. #9
    Guest
    Join Date
    Feb 2019
    Location
    Edinburgh
    Posts
    9
    Rides
    0
    Hi mate , thanks for the reply and info �� I’ll have a look at the throttle tonight after work and let you know how I get on. Yeah the idle does sit low couldn’t give you a exact amount right now but I’ve not touched anything in that area and I put the original ecu back in and it was still faulting but will defo give that a look at . It’s as if the cars running on three cylinders but when driving in gear it seems fine .

  10. #10
    Guest
    Join Date
    Feb 2019
    Location
    Edinburgh
    Posts
    9
    Rides
    0
    So quick update guys . I checked all earths on the car and all seem good . I carried out a flash test and it came back with 3 long flashes and 4 short - 34 knock sensor fault. I don’t think a knock sensor causes a misfire , it’s just picking up that their is a misfire . The car drives fine and doesn’t suffer any flat spots or misses when driving . Only happens when idling when hot or coming to a stop. Could this be caused by the neutral position switch not being connected ? I’m also running a light flywheel from Driftworks , would this cause a misfire when idling ? I understand the car doesn’t read engine speed from the crank so not as if the flywheel could be fitted incorrectly i.e crank sensor issue. Any thoughts ? Cheers Mark

  11. #11
    Guest surewire's Avatar
    Join Date
    Mar 2016
    Posts
    36
    Rides
    0
    There are some ways to check idle issues.

    Try cleaning and adjusting the IACV. There is a idle screw that you can adjust.

    Also a vacuum leak can make the car stall when braking.

  12. #12
    Guest
    Join Date
    Feb 2019
    Location
    Edinburgh
    Posts
    9
    Rides
    0
    Hi mate , I adjusted the screw at the top of the intake plenum for the iacv , this has stopped the misfire so I’m going to strip and clean at the weekend then adjust the throttle correctly . I suspect due to the throttle being set up fo a auto and with the light flywheel set up and manual transmission the car couldn’t correct , I also think the iacv has not been touched in its 21 year life span so it’s sticking . Cheers for the help guys . Much appreciated

  13. #13
    Guest vespamant5's Avatar
    Join Date
    Dec 2016
    Location
    Birmingham
    Posts
    47
    Rides
    0
    You can connect the nps were the auto box control unit was by joining the two wires and and swapping the one on the side of the fuse box to the correct wire. All different colours by the way and connect the reverse lights though the same plug you can cut of the auto box loom. I did the same thing and it was easy to sort out


    Sent from my iPad using Tapatalk

  14. #14
    Guest
    Join Date
    Aug 2012
    Location
    Essex
    Posts
    8
    Rides
    0
    Just done my Manual swap and only disconnected the ECU where the clutch pedal is. Car runs and drives fine. Inhibiter switch bridged obviously, other than that all auto wireing

Posting Permissions

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