CFI to MPI rewiring Tutorial - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

NZ · 10-28-2002, 00:25

For those who have done the CFI to MPI conversion you will no doubt run into the problem of the car not idling because the Idle Speed Control circuit is slightly different on an MPI.

Here is how to fix that.

1. On the old plug that the CFI Idle motor plugged into (it has 4 wires, see pic) cut the Grey/White (with red bands) wire.

2. Extend the wire by about 2 to 3 inches.

3. Wire the extended wire into the engine loom side of the Injector Loom Plug in the hole as shown in the next pic.

This hole should corrospond with the thicker Grey/White wire on the Injector Loom side of the plug

Reconnect the plug and start your car!

jamesk · 10-28-2002, 04:30

hmm so that ide speed motor does go on the mulitpoint engine...
we tried to do a cfi-mpfi conversion not long ago and the car we took the mp stuff off didnt have the motor and we cant see it pictured or mentioned in the manual except under the cfi sections so we assumed it didnt use it.
never ended up getting the car to start though (no spark) so the cfi went back on.
couldnt see anywhere on the throttle body to attatch the motor.
you wouldnt happen to be able to get a picture of it by any chance ?
or does the mpfi not actually use the little motor ?

NZ · 10-28-2002, 08:49

Yes the MPI uses a motor - not the same one as a CFI. The MPI motor is mounted near the throttle body. If i is missing you will see 2 holes instead. I will get a pic up.

Hidden_Soul · 11-21-2002, 01:30

after an hour or so pouring over the schematics for the E series I worked out what the wire does, it controls the air bypass solinoid which allows air to bypass the throttle body at idle, the reason the idle is stuffed is it is flooding as no air can get in, on the cfi this wire pushes the throttle open a bit to allow air in, on the MPI there is a seperate solinoid that isnt part of the ISC

SiX_iN_a_RoW · 01-28-2003, 03:17

NZinAUS, how did you go about wiring the extended wire into the plug. Im guessing there was a vacant hole which you inserted the wire into..did you solder it of just push it in and tape it there?

I am seriously looking into the MPFI conversion very soon and want to know as much as I canbecause I dont have internet access where I will be doing the conversion ( Brisbane )

SiX_iN_a_RoW · 01-28-2003, 03:31

Without having to start another "MPFI Conversion" thread.
Could someone please let me know of the tricks involved in the conversion.
I know the majority of it is a bolt on swap, but besides the wiring loom ( as mentioned above ) what else has caught people out?
How is the heater/coolant pipe sorted out etc etc
ANY experience/info would be so so so very much appreciated!

Oh and its a 3 speed Auto which should make the wiring a little easier shouldnt it??

Brent79 · 01-28-2003, 06:06

Hey Sixa! When mine was done, for the coolant pipe i cut about an inch off the exsisting thermostat housing pipe and used a rubber heater hose to connect it under the intake manifold to the heater valve at the rear of the engine. With a 3 speeder it will make yer job alot easier! If you had a 4 spd, you would have to extend the gearbox TPS about 30cm so the connector could reach the throttle body. Dont think karl mentioned it but on mine i had too connect the other side of the ISC solenoid to the red wire from the purge solenoid.

Brent

NZ · 01-28-2003, 13:43

Brent i dont actually know how yours idles, because i couldnt get it to work the way you told me. Scott Hart did the rewire for me, so he had the liffle clips that go in the plug, I guess you could wire it without going through the plug. The ecu relay also needs to be changed as the CFI actually has a timer relay and it leaves the ecu on for a few seconds after the car is switched off. It does that to reset the throttle so the car will start next time. From memory there was 2 pins on the relay that had to be swapped around. Anyway in good time there will be a CFI to MPI tutorial from start to finish.

SiX_iN_a_RoW · 01-28-2003, 14:00

excellent stuff, look forward to reading through the article.
I am going to buy the parts, make sure I have EVERY THING I need then give myself a few days just in case something goes wrong. I see your point with the conector NZ...might just bypass the plug and use some bullet terminals instead.

Brent79 · 01-28-2003, 21:14

Yeah Karl, mine was ****ed up big time the 1st time so we had to start rewiring from scratch. Basically I routed that white/grey wire to one side of the ISC solenoid connector and the otherside went to the red wire on the purge/injector ground. If you look at a schematic for the MPI EFI, u will see that the ISC solenoid is in fact connected up this way. Doesnt really matter how its done, as long as the correct parts connect to the right pins on the ECU. My car runs and idles perfectly so im happy with that setup.

Brent