d14a4 from a ej9 to d15b2 (from a eg4) problems with vtec

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Hi guys, i have a couple problems with a engine swap that has been carried out, i have managed to swap over engine gearbox driveshafts, mechanic is using the loom from the d14a4 on the d15b2, the car starts, but with the ej9 that the d15b2 is going into the ecu is a non vtec, so the idle is jumping up and down between 1000 and 2000 revs, how do i remedy this issue, please help?

Info for the car the engine came from is as below:

  • VTEC
  • Found in:
    • 1991-1999 Honda Civic VTi EG4 (Japanese Market)
  • Displacement : 1493 cm³
  • Bore and Stroke : 75 mm X 84.5 mm
  • Rod Length : 137 mm
  • Compression : 9.6:1
  • Power : 128.22 hp (130 ps) @ 6800 rpm & 101.9 ft·lbs (14.1kg/m) @ 5200 rpm
  • Redline : 7200 rpm
  • Fuel Cut : 7411 rpm
  • Valvetrain : SOHC VTEC
  • Head Code : P08
  • Fuel Control : OBD-1 MPFI
This is the spec of the car the above engine is going into:

  • Found in:
    • 1996-1999 Honda Civic EJ9 (European Market)
      • Displacement : 1396 cm³
      • Bore and Stroke : 75.0 mm X 79.0 mm
      • Compression : 9.2:1
      • Power : 66kW (90 hp) (civic is)
      • Valvetrain : SOHC non VTEC 16v
      • Redline : 7200 rpm
      • Fuel Control : Multi-point fuel Injection (PGM-FI)
      • Transmission: S40
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You can remedy this by either getting the correct ecu because the D15 uses a 2 wire IACV and the D14A4 uses a 3 wire and a 3 wire ecu won't run a 2 wire IACV or you can put the D14A4 throttle body on the D15 intake manifold. It will fit but you have to cover up a small round hole in the corner to make it idle correctly. If you compare the two manifolds you will see how they are different.
I have the d14a4 inlet manifold on the d15 engine, but it still does the idling problem, is there something im still missing?
Check your vacuum hoses and your intake manifold gaskets. An air leak will cause your car to idle higher and are you getting a CEL by any chance?
check engine light. The yellow light that shows up on the instrument panel when the ecu senses a bad sensor.
Ahh yes sorry, that is on, and the idling is jumping when in nuetral, i can rev the engine fine it will rev up, but as soon as i come off the gas the engine just jumps up and down at idle.
Well if the light is on then figure out what code its throwing. This should tell you what is causing the problem and allow you to fix it.
we need to change the ecu over to my P08 ODB1 at the moment i have the P3Y which is proving to be a royal female dog to work out how to convert harness over to fit the P08. If anyone has any ideas please hola.
anyone got anything with regards to ideas or know how on this problem?