i have a 1990 gtu that the rear rotor had no compression the engine was replaced with a 1986 s4 motor will the ecu work and why wont my car start ive checked timing ive got spark and im flooding so i know i have fuel i havent checked to see if injectors ar stuck open yet but will very soon need help any
good ideas welcome

also thinking or dumping ps would u advise

 

if you dropped an s4 motor in your s5 I don't think it's gonna work, The ecu's are different between series. I don't know exactly what you need to do to switch between sereis, but you still probably have alot of work ahead of ya. I know the wiring harness would need to be re-pinned into the right locations for the s4 ecu.

 

When you swapped the motor did you keep the 90's the front cover, fuel rails, injectors, TB, & vac rack?

 

yes i kept everything from the 1990 motor i was going to use the 90s whole intake system but the lower nut on the manifold is rounded and i wasnt able to find a tool to remove it any suggestions

 

also does anyone know where i can find 1990 gtu injector clips not the whole harness just the clips and about 5" of wire still attached

 

I have a complete body harness from an s5, I'll let it go for $120shipped, thats what I paid for it but never used it. I know thats a kick the nuts when you only need the clips.

 

thanks but no thanks i dont have that kinda cash just for a harness i only need clips from this motor swap is on an extream budget thats why i put a lower horse 86 motor in my 90 gtu but thanks anyway

 

The deal is the major change to the ECU functions from 88 to 89.
The S5 ECU will squawk a code & default if all of its sensors & solenoids are not plugged in.
The S4 wasn’t so fussy.

When you do an S5 vac simplify:
A solenoid or a ballast resistor is needed for each plug.
The MOP must be at least plugged in and the wide range TPS must be on the TB to run it.

 

Lesson 1.
Cheap and Rotary don't go together

 

i used the 90 tb so that i could easly incorporate the tps