DOHC 16V Conversion instructions


Parts needed (assuming you have a running 8V 2.0 DOHC EFi engine)

1. Scorpio (NOT RS2000) 16V cylinder head COMPLETE .
By complete I mean basically EVERYTHING
 from the head gasket upwards. That includes the whole inlet system.

2. RS2000-16V ECU (from a non-PATS car, 1991-1994 'should ' be OK)

3. RS2000 injectors.

4. EDIS4 module

5. Two HEGO's (and weld in bosses if needed)

6. Inlet piping from the 16V Scorpio

7. Universal cone air filter

8. Breather filter (for cam cover)

9. Various gaskets, head bolts

10. PCV piping

11. Exhaust parts depending on what you want (will be covered in more detail later)

12. Rev-counter thats compatible with EDIS4

13. RPM switch for the VIS system

14. Solenoids/relays ect for the VIS system


The conversion.

1. 1st to do is decide what you want to do about the exhaust manifold.
You have two choices, use the Scorpio manifold and downpipe (which is restrictive but easier to do) or fabricate a 4-2-1 type manifold (recommended but not easy)
For the easy solution use the Scorpio stock parts (manifold and downpipe) and  modify the downpipe to join onto the exciting exhaust system.
The 2nd (and better option) is to fabricate a manifold/downpipe. A good tip is to source an RS2000 manifold and cut the flange off and use that as a starting point.
It's recommended to build your manifold with the 16V head mounted on a block while on a bench. If you do it with the engine fitted into the car it will be VERY difficult.

2. After dealing with the exhaust you need to prep the inlet system on the 16V head, basically all this involves is removing the ERG system (you can crimp off the steel pipes) and removing the Scorpio injectors and fitting RS2000 ones.

3. The next step is fairly easy, just basically remove the old 8V head COMPLETE and re-fit the 16V head COMPLETE with inlet manifold fitted (please note you 'may' have some space issues with the braking system and inlet manifold on a RHD car but nothing that can't be fixed) It is important NOT to forget fitting the PCV pipes BEFORE fitting the 16V head. Remove the 8V inlet ducting and air box. Re-fill the coolant system (modify coolant pipes where needed) Connect the brake servo to the VIS inlet. Connect the MAP sensor to the VIS inlet. Connect up the fuel supply and return.

4. Now the head should be fitted and all bolts/covers ect done up. Now fit the small breather filter to the cam cover.

5. Fit the Scorpio inlet ducting, you will need to fabricate some means of securing it to the car. Fit the universal cone filter to the end of the inlet.
Please note the inlet ducting MUST have air temp sensor fitted (this is standard on the Scorpio inlet ducting)

6. Now back to the exhaust system. If you have made a 4-2-1 type manifold you will now need to weld in two HEGO bosses onto where pipe 1&4 and 2&3 meet.
If you used the Scorpio downpipe there should be one HEGO already there, so just add another somewhere near to the exciting one (not ideal but better than nothing)

7. Fit the exhaust system (sound easy, most likely won't be though)

8. Now some fun. You will need to make an engine loom. Your best bet is to use the Scorpio loom and fit the Sierra plugs/sockets onto it. With the RS2000 and Sierra wiring diagrams its easy to sort this lot out. If you are scared of wires and think that electric is the work of Satan then buy a Pinto, use a carb and go back to the stone age.
Make sure the injector wires are paired 1&4 and 2&3 (as standard the Sierra is 1&2 and 3&4)

9. Now you need to fit the EDIS4 module, just bolt it onto the inner wing wherever its easy to fit.

10. Wire up the EDIS4 module to the coils and switched 12V power supply. Don't forget to give the EDIS4 module a GOOD earth.

11. Remove the cars old coil (the switched 12V feed to the coil is ideal to use to feed the new coils and EDSI4 module) Connect PIN2 of the EDIS4 module to the negative side of the old coil (to feed the rev-counter)

12. Connect the CPS to the EDIS4 module. The old wires that went to the CPS (they go to the ECU) now need to be connected to the EDIS4 module too. Make sure PIN1 of the EDIS4 module is connected to the blue/green wire of what USED to be the wire the went to the CPS and PIN3 to the blue/yellow wire of what USED to be the wire the went to the CPS.

13. Now the engine loom should be fitted, EDIS4 module fitted and wired up. Double check all that.

14. Now inside the car. Remove the old Sierra ECU. Now locate PIN30 on the ECU plug and cut it (not needed)

15. Remove the wire that goes to PIN36 (you MUST remove wires when needed complete with the pins, removed the RED insert in the plug and its easy to do with a small screwdriver to release the locking tabs)

16. Remove PIN55 and place it where PIN36 used to go, this now completes the circuit for the EDIS4 module

17. Remove PIN4 (not needed)

18. Remove PIN3 and place it where PIN4 used to be (this is for the VSS)

19. Now you need to PINs added for the HEGO inputs for the ECU. PIN29 (HEGO1 for cylinders 1&4) and PIN43 (HEGO2 for cylinders 2&3)
If you already have a CAT sierra then PIN29 is already there so you will only need PIN43.
Run wires into the engine bay ready to connect to the HEGO's (A tip, if you have a CAT Sierra then you can use the wire the USED to be PIN36 which now isn't in use, this goes to the now unused TFI module, cut the wire at the TFI module and you ready to connect to your HEGO.

20. Connect your HEGO's. Try not to get them mixed up. You will now need a power feed for the heaters in the HEGO's. I used the power supply that already went to the HEGO as mine was a HEGO equipped Sierra anyway. You could use the old 12V feed that use to go to the now unused coil. For the earth for the HEGO heaters just connect to anywhere convenient.

21. Now the engine wiring should be done and the HEGO's fitted and wired up, double check everything.

22. Now before going onto the VIS we can see if everything done so far works. Time to start the engine but 1st block of the one VIS vacuum connector that is left so there is no air leak.

23. If you haven't made any mistakes the engine should start. If it doesn't recheck everything.

24. With the engine running its a good idea to connect a strobe light to check the EDIS4 module is working correctly (if OK the timing should be jumping about when revved a little)

25. If everything is OK then its time to sort out the VIS.

26. You can either just leave the VIS diaphragm connected directly to the inlet (easy, but no control) or use an RPM switch with a solenoid for a controlled activation of the VIS.

27. Fit rev-counter

28. It would be a good idea to connect a fault code reader to make sure everything is OK.
If OK you should just have two fault codes, 71&73