cfi to sefi....

June 04, 2005, 04:26:38 PM

has any one done the cfi to sefi swap? if so what does it intale and how mutch work am i looking at? i already know i need the upper and lower intake the throttle body and the harness and comp and micilanious sensors. but what elts could i be missing?

Re: cfi to sefi....

Reply #1 – June 05, 2005, 12:31:59 AM

The SEFI computer and Harness will be neccessary. As has been said a lot of times, it might be easier to get a donor car... get an HO car while you're at it. Preferably a mustang, because MN-12's are all wierd. But for just a basic SEFI swap, easiest route will be to pull a computer, harness, any sensors you can get (even if you replace them with new ones later) fuel lines, etc from an SEFI fox car, like an 86+ T-bird or Cougar.

Re: cfi to sefi....

Reply #2 – June 05, 2005, 07:38:08 AM

IMHO, i dont really think all that much is needed and you could still use your existing eec,harness, lower intake, and not need the upper.

there is no such thing as an 88 and down tbird and coug 3.8L sefi (its called bank fire) The 86 and up 5.0's are the only true sefi's.
the 88 and below 3.8L engines (including older CFI) were called bank fires systems. **this is also true for any 5.0 cfi system which are pinned out just the same as the 3.8L injection. the injectors were divided into two groups and the eec provides ground to these two groups.
example,,
-cfi systems have a red wire which is tied in to the power through the speed control and tps. One injector would have ground provided to it by pin 58, the other would get ground off pin 59 at predetermined intervals by the eec.

on the 88 sefi 3.8L, its the same deal, three injectors fire off pin 58 and the other three fire off pin 59.

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here is some configuration info for you to stew on...........

Fuel injection configuration
2.3 L engine (bank fire)
inj 1, 2 pin 58
inj 3, 4 pin 59

1982 - 87 3.8 L engine CFI (Bank fire) including all earlier 5.0's(larger CFI which is a nice mod to a 3.8 and bolts right on)
inj 1 , pin 58
inj 2 , pin 59

1988 3.8 L engine 6 injectors (bank/batch fire)
inj 1,2,3, pin 58eec to cyl 1,2,4 respectively
inj 4,5,6, pin 59eec to cyl 3,5,6 respectively
*inj 1,2,4 fire on first shot
*inj 3,5,6 fire on second shot

1989+ 3.8 L engine 6 injectors (sefi)
pinouts,, not sure

5.0L 1986 + (sefi)
inj 1 , pin 58
inj 2 , pin 59
inj 3 , pin 12
inj 4 , pin 13
inj 5 , pin 14
inj 6 , pin 15
inj 7 , pin 42
inj 8 , pin 52

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here is what id do to keep things simple sweet and to the point so you dont have to worry about using an upper intake and all the extra rig a ma roar stuff to over complicate the mod.

remove the cfi and kiss it goodby
remove and drill the intake for injector bungs
obtain a fuel rail from a donor and install it (fab up mounting)
snag a harness or just extend the existing one you have
bolt the intake / fuel rail / injectors on the car
now you have two CFI holes sitting there
Id use these holes to custom make an air cleaner that bolted on right there

this is possible so give it some thought, sorry if i made it sound to simple but it really isnt something out of reach and the expense isnt really needed.

NOW,,, if your interested in being true SEFI instead of the bank fire system,, your existing eec may provide the setup you want. ask thunderchicken for turbocoupe50 if the pins 12,13,14,15,42,52 are "active" even though they are unpinned on your eec. I dont know for sure but if they are then you could run individual "so called ground wires" from each and have all 8 injectors firing at different intervals.
im not sure if you are a 6 or and 8 cyl engine, you did not say but this should help. If you can find out about making it a true sefi, then that would be the route id take and id used nothing new but a fuel rail and some wiring.

again, this is something that can be done and you really dont need the harness, sensors, upper intake, ect ect ect., just an open mind to how things are set up.

just because there are muliple injectors doesnt really mean its a true sefi engine, the 88 3.8L engine is no different than a 85 with cfi!!!!, just a bunch of added stuff and different heads for injectors /upper intake, ect.
drilling the intake to add injectors defeats all these needs.

Re: cfi to sefi....

Reply #3 – June 05, 2005, 10:54:27 AM

well ive been weihing options and i whant all around power and drivability and the only engine i know out of the 5.0 family is the sefi ones perferably the 88 ho 5.0. so i just might whanna just swap entire motors and harness and comp and just go that way unless the way you are talking would work and also prove to be drivabul and benifical for power and fuel economy. but thanx for some crazy off the wall ideas.