I have an 88 gxl.
The first motor lost its coolant seals 3 years ago,
I had a s5 motor installed with my old s4 front cover and omp fitted to it.

I have since swapped the bumpers and side trim guage cluster ect to s5 so my car has a s5 engine and appears to be such.

now this motor is losing compression and I have located a s5 motor and trans with all the s5 accesories, both harnesses, ecu and everything underhood.

so the question is when I swap in this motor do I swap the omp on it and leave everything be, or swap my whole car to a s5 and run with that?

I have replaced both harnesses in the past and am comfortable pulling the dash and motor ect. but I am not sure its worth the swap, limp mode and an electric omp seem stupid to me.

so then what does the forum think?




Note the flapper afm there

 

do it do it do it. Just switch evrything out so its fully s5. Dont convert the s4 harness into a s5 harness, cuZ thats what JPR motoring did to my car, and I have tons of electrical issues... Just switch the whole harness out and ecu and replace with everything s5. Im thinkingabout to do that too.

 

Yes do it for even the simple fact of having a check engine light so you can know when something is wrong with your engine. If you checked I'd bet your S4 ECU has some stored codes. I have two S5 drivetrains. One in a S5 and one in a FB which has S5 EFI wiring in it. Both OMPs are fine and have given me no problems. I don't see why anyone would be worried about them. Plus the OMP is more accurate and you don't have to adjust it. When was the last time you adjusted your S4 OMP? Never I'm sure just like eveyone with a mechanical OMP. So how do you expect it to work right? Everything about teh S5 is better. There are differences on plugs on the mainharness though between the two so you need more than a harness. Also even though the warning cluster has the same plug you will need a S5 one since the pinout is different. Don't worry about the plugs for the power seatbelt junk. If you leave it unplugged it won't keep the seatbelt light on. In my S5 I converted to S4 belts and there's litterally nothing plugged in to controll them but no problems with the seatbelt light. You will need a new harness for the headlights switch. The small one that goes from the main to the switch. It's different. The cruise control module has a different plug as well so you will have to get the S5 one. Theres some other stuff but I won't list it all. Oh and your door harnesses won't plug in that's a big problem so get the door harnesses as well.

 

I disagree, why mess with success. If you have a S5 motor set up to run in a S4 box already why change it. I say keep the wiring. I trust the mechanical OMP a lot more than the S5, Plus you going to have to take out the dash and change the body harness if you go S5.

 

this is called scraping the bottom of the barrel for a project