Engine swap romulator tuning questions.

  • #1

    Engine swap romulator tuning questions.

    Here's what I had.
    87 turbo with an 86na engine full stock intetnals with a 88na ecu with the romulator. The car ran pretty well with a bit of a messed idle bit it was more than adequate. The made 401hp 404ft-lbs at the wheels. Everything is basically the jwt 420 setup.

    Here's what I have.
    Same 87 turbo now with a rebuilt 88 or 89 w series na engine pushing over 200lbs per cylinder compression. Same 88 na ecu and romulator and jwt type setup. The car idles at 17-18 AFR which of course is way to lean and a bit lean under boost (23psi). My idle is the worst part. What locations in the ROM Editor affect the idle? It's been way to long since I've done any of this so my brain just isn't functioning properly. The biggest problem seems to be related to ignition timing and setting base time has been a bit of a pain in the ass.


    boost. does a body good!
  • #2
    200psi?

    And is your tps adjusted?
  • #3
    Injection latency sounds like your issue - but it should be unchanged given the same injectors - and I'm not sure where to find that in the ROM editor.
    - VG30DET (HE341) 86 300ZX - 1982 280ZX Turbo - Headered NA 1986 300ZX 2+2 - 2000 Xterra -
  • #4
    I would imagine that the increased compression 160lbs to over 200 in the cylinders would need some tuning for sure. That's the biggest change with the engine swap that I wasn't expecting when I ran the compression guage. I know base timing for the older vg was 20° and the w series engine wants 10° and I have my distributor set full lock to the right for 12°. I've gone over everything and it is all set properly as far as the timing belt/distributor goes.


    boost. does a body good!
  • #5
    If your distributor is full lock to the right its not 12°. A/B or W, right around middle should be 20°. The head/dizzy/plate didnt change, they just set it differently.

    A retune is never needed going from a 145psi VG30ET to a 180psi VG30E, or a VG33, so I can't see it being needed for your change. Judging by your abnormally high compression tests and your timing only being 12deg at full lock I'd say cam timing is off.
    - VG30DET (HE341) 86 300ZX - 1982 280ZX Turbo - Headered NA 1986 300ZX 2+2 - 2000 Xterra -
  • #6
    Also, your base timing should always be set to match what your tune is expecting at idle. The mechanical engine doesn't care.
    - VG30DET (HE341) 86 300ZX - 1982 280ZX Turbo - Headered NA 1986 300ZX 2+2 - 2000 Xterra -
  • #7
    It's a w series engine that has a base time 10° not 20°.


    boost. does a body good!
  • #8
    The mechanical engine is irrelevant. The base timing was changed to 10deg because the tune was changed. Always match base timing to what your TUNE is expecting.

    And your cam timing is off if you're maxing at 12.
    - VG30DET (HE341) 86 300ZX - 1982 280ZX Turbo - Headered NA 1986 300ZX 2+2 - 2000 Xterra -
  • #9
    Sorry I just realized I gave a bit of miss information. The distributor is turned full left for 12° so 20° will be roughly centered. I haven't been out in the garage for a couple days. :-/ I have bin files for both early and late single overhead vg's.


    boost. does a body good!
  • #10
    Finally had time to mess around a bit. I thought since the w series engines base time is 10° that's where I had to have it set. All my maps are for 20°. I reset the distributor to 20° and smoothed out my old fuel maps a bit along with knocking my timing maps back just a hair. I had my timing pretty far advanced on the old setup. Needless to say the car is now running better than before with much more room improvement. Thanks for the help.


    boost. does a body good!