shelby4130

Ok so i swapped out my engines and put a 91 into an 88. I am using the old wiring harness as i have to. Well, there are 5 female solenoid plugs on the new vaccum rack but on the old wiring harness there are four male plugs.....(orange, blue, yellow, gray) and one different plug thats teal. What do i need to do to work around this? Should i leave one unplugged....if so, which one and what would it do? Or is there another way? I also have that other plug that has nowhere to go it seems. Anyhelp would be highly appreciated. Thanks.

Scott 89t2

I think the 5th is for the S5 VDI which will no longer work...

what you really need to do is strip everything off each engine and bolt all the S4 stuff onto your new one. manifolds, injectors, fuel rails, vac rack. everything.

did you plan on premixing? or did you swap the front covers and OMP already?

shelby4130

I haev the new fron cover and the electric OMP in the car now.....and i dont really want to have to premix. I already changed the fuel injectors though and the only thing that seems to be standing in my way are those vaccum rack silenoids. Which one is the "useless" one? And where am i going to plug in the plugs that will go in?

Scott 89t2

so the electric OMP is on but you are using the old harness and ecu? the OMP won't work... you'll need to premix.

hypntyz7

Your old s4 car (and it's wiring, and ecu) can NOT run any of the newer 89+ stuff...elec. OMP, TPS, VDI, 6th ports, etc. THe white and tan solenoids on the s5 rack are for the VDI intake valve and the 5/6th ports (computer controlled). The s4 ecu/wiring does not have a way to run this stuff, even if you spliced wires. You need to run all the s4 stuff for simplicity, including the s4 front cover, OMP, throttle body with TPS, and injectors. IF you want to use the newer manifolds, you can do so, but the VDI valve in the middle intake of the s5 will not work, so you'll need to wire that open, and suffer a bit of a weak low end. Same for the 6th ports, unless you come up with another way to run them. THe 5/6 ports should open at 4krpm, the VDI at 5.5krpm.

shelby4130

But i cant use the intake manifold from the S4 because it doesnt line up. It wont fit with the block...or will it?

hypntyz7

you can use the s4 intake if you dont need to pass emissions. use a whole lot of jb weld to pack into the port air passage in the int. housing below the primary intake ports, otherwise this will be a vac. leak.


if you do, you need to use the s5 lower intake, with the stud closest to the firewall removed. then you will have a better chance of passing, but still not guaranteed.

shelby4130

the bolts dont line up from the S5 block to the lower S4 manifold....how is that supposed to work....i mean, it just wont fit. Maybe i just dont understand what your saying

hypntyz7

That's odd, seeing as how all 6 port lower manifolds share the same bolt pattern. Last week I put an s4 manifold on an s3 (GSLSE 84-85) block, and I have done numerous swaps with s4/s5 blocks/intakes. You must be mistaken, or you must be trying to use a turbo setup??

shelby4130

no none of this.....the holes for the bolts on the S4 lower manifold are about a centimeter or so too narrow to slide onto the S5 block

shelby4130

i would definitely like for it to just fit nicely ...but it doesnt

hypntyz7

ok man, you're right. I dont know what Im talking about. Ive only been doing this every day for 5 years...

shelby4130

no i am not dumb at all......they REALLY DONT FIT

shelby4130

ok so nevermind that then since that obviously doesnt seem to be working.....how would i get around that by using the S5 manifold? There are too many things that are becoming problems like the vaccum rack silenoids. There doesnt seem to be an easy way around all that.

hypntyz7

There is usualy not an easy way to get around swapping stuff between series...this is a no-no with rx7s in general. IT can be done, but generally only by someone who knows what parts will swap, and what has to be done to make it happen...a plan of sorts.