hello everyone, purchased a 1991 fc base model last year, bought it with the engine out and taken apart, from a bad coolant seal. so i have a running s4 engine sitting on my shelf from one of my old cars. i know the s5 has the EOMP, and will go in limp mode without it. from all the other threads i’ve been reading i haven’t found if anyone has found a way to fool the EOMP into thinking it’s working to avoid limp mode. i plan to use the s4 short block and use everything else from the s5 car. intake-injectors-sensors etc. i don’t want to take the front cover apart and change it to the s5 one as i plan to run premix. i’m just curious if anyone has gone threw a swap like this. i’m not taking wiring harness’ apart or swapping computers or anything like that, i’m simply trying to make the car run and drive while i can save up and slowly build the correct engine for the car. thanks in advance for any help.

 

Install everything from the S5 onto the S4 block, except the front cover. Remove the OMP from the S5 cover and plug it in and zip tie to the frame if you are unwilling to swap covers. Use the S4 OMP, if you can, but I think the linkage would be an issue. I would still premix.

 

Something tells me He would need the S5 throttle body as it has the TPS..

 

Why not just swap in an S4 harness and ECU and use all of the S4 stuff? No worries on the EOMP and it will simplify things a shade? Just a thought.

 

Because the body harnesses do not match and it's more trouble than it's worth. The easiest thing to do if he has a S4 block is to strip it and dump it in and hook up all S5 parts. Since he doesn't want to remove the front cover, leaving the S4 cover with the OMP will still allow OMP mechanically. The S5 ECU needs to see the EOMP to keep it out of limp mode, hence why you plug it into the connector and just ziptie it aside.

 

+1 to putting all the S5 accessories on the S4 block, use a block off plate for the EGR if it has one and you should be good to go. The S4 has slightly heavier rotors in the motor, so you will want to use the S4 flywheel/counter weight .

 

well since the engine IS an S4 there is no reason to use the S5 Flywheel..it doesn't match the rotating assembly of the engine being used.
No matter if the engine is an s4 or an s5 you need the Same series flywheel for the engine being used as it corresponds to the rotating assembly.
If not you will have unbalanced internals. ( IE: s4 front counterweight,s4 rotors,and an S5 rear counterweight/Flywheel).
So in short you can't use the S5 Flywheel in this case,

 

did you ever get this thing running? I have a s5 car with a s4 engine. That I'm having issues with.
S4 engine with s5 engine harness/s5 ecu / omp I moved inside the car. Under the dash. It's plugged in so it won't go into limp mode. Using the S5 Afm / S5 injectors/ S4intake with S5 Tb and tps/ wondering if that's where I messed up. Do I need to use the S5 lower and upper intake with it?

What the car does now. It starts and all. It's starts cold really good and warm.. but after I start it, if I go to give it some gas. It just chokes up. There's no response..

 

that member hasn't been on the site since 2018. probably be best to post in the 2nd gen section.

 

hey man! Did you ever get it going good im in the same situation. And had some questions, please let me know thanks!