zimmyjim

im switching the motor in my car as the PO overheated the S5 and CUT it out and bought an S4 to go in it...
my issues as of now are:

1. which wiring harness do i use?

2. ive rehosed my mech OMP but ive read that
the computer needs input from the elec OMP
to stay outta limp mode...is there a bypass for this?

3. im sure theres more to come,..any more issues i should
be aware of?

i had a 85 RX7 a few years ago and im a pretty decent mechanic...
thanks for any help u can provide ...zimmyjim

farberio

iTrader: (7)

S5 wiring harness and S5 accesories/intake

Plug in the OMP and just leave it somewhere. The computer will see that its there but it won't do anything.

There is plenty of threads on this, a search with some careful word choices will yield a treasure chest of info.

lonewolfrx

http://www.rotaryresurrection.com/2n...o_s4_swap.html

that should help you out

zimmyjim

thx guys...
1. some of the connectors on the S4 engine
dont match the S5 connections..do i need to do
some connector switching?
are the harness esentially the same as far as wiring goes?
i have a haynes and will b researching this, but i want
opinions from some of u bcause im car less at the moment
and need this runnin soon as possible...


2. mounting the elec OMP somewhere was what i was
thinkin too..was hoping maybe the was a "resistor"
type bypass i could make instead..

3.im going over all the 2nd gen post..but it takes time

farberio

iTrader: (7)

The harness are very different from S4 to S5, you need to use all S5 components minus the S4 short block.

Here is an active thread with the same Q and some more info: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/swaping-s4-s5-932251/

zimmyjim

thx..thats my plan .... which throttle body should i use?
can i just switch the S5 injectors and TPSs to the S4?

misterstyx69

iTrader: (142)

You'll be using the s5 harness,so you need the S5 Throttle body,as it has 2 TPS's on it.
The s4 only has one.

zimmyjim

it looked like the TPSs on the S5 could easily b switched to the
S4 TB...not sure, but it looked like it...
i like how the S4 body looks better than the S5...otherwise...
are there any performance differences?

cantera

ive got a question as well; is the exhaust from the cat back different on each model? or interchangeable?

farberio

iTrader: (7)

^ you really shouldn't crap in other peoples thread. As far as I know the catbacks are the same. The only difference in exhausts is between turbo and n/a.

farberio

iTrader: (7)

The S5 intake is about a 10-12hp gain from the S4 intake thanks to the VDI port.

cantera

hah. sorry abuot that, but thank you very much berberio

zimmyjim

S5 it is then! thx ..z

autocross_diva

iTrader: (1)

how are you coming along with this swap? Due to money issues my project had to take a hold but I am already working on the tear-down.

86rx786

You're the one crapping on his thread with that comment.