S5-->S4 swap HELP WONT START
 

Alright here is whats going on...

S5 TII into a 88 GXL
I have a redom N374 ecu and im still using the s4 under the dash harness

i followed this write up
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/how-splice-s5-tii-engine-into-s4-chassis-703692/

where i seemed kinda confused was this

"Start off with the one with the wiper blade plugs find a ground to splice into then wrap some tape around it to hold it in place then start splicing in the needed wires for the second plug....you will have to run a wire off one of the black with white stripe wires and put it with the three wires that from the S4 #3 plug"

and

"In the end you should have a complete harness with the 4 wires for the battery,main relay, fuelpump relay,and starter swtich hanging out "

now 1a battery constant is tied into where 3j s4 ran to and IS getting 12.95 volts so it is receiving power.

s5 wire 1b battery constant is ran to the wire where 3j s4 wire met at on the fem2 plug

my 1b main relay i was sorta lost as 1b meets up with a B/W wire where it splits into two b/w wires so i didnt know if i needed to use both or 1 and if 1 what one do I use?

1c s5 ignition switch is ran to the b/l wire where 3b s4 met at

1k s5 fuel pump resistor relay ties into the b/w wire that 3d ran to off of the s4

now my head lights work, blinkers, and door open beeping works, but everything is dead no starter no fuel pump so im lost.

Any help will be greatly appreciated

Are you using the Interlock switch as part of the start circuit? Yea or nay?

Are you using the Starter Cut Relay? Yea or Nay?

to be honest I dont know, where would i look to see if they are there, or being used? Sorry I can turn wrenches, but couldn't plug a light in to save my life.

The relay I speak of has one plug w/four wires. Two Black/Green wires, Light Green/Yellow and a Black/White wire. This relay is located next to the Main Relay that has two plugs. If you do have this relay then the two B/G wires act as follows. One would have voltage w/key to on while the other has voltage w/key to start. See if you have this relay or not and if you do then check both of the B/G wires and see if they behave properly.

nothing to the wires with it to the on position and nothing when i hold it like im trying to start it

Your ignition switch might not be receiving power so this is one possibility. W/key to on do the blinkers or windshield wipers work?

blinkers dont work, wipers are removed. straight track car so nothing but what makes it go

You need to look at how the cable comes from the Main fuse on the side of the Engine fuse box that is closest to the firewall. The Black cable drops below the fuse box by about a foot and connects into another cable that runs to the ignition switch. To prove that the ignition switch is powered you can look at the plug w/a Black wire and a Black/White wire connected to the ignition switch along the steering column just under the dash. The Black wire in this two wire plug would have constant voltage to it.

HAHA k so back of the fuse block the wire off of the 80amp is gone. i have one that i think goes right there but it just has a clip that fits onto a flat barb that i plugged in and a covered circular clip that looks like it would go on the + for the alt or something

Don't you have another RX-7?

k so now it cranks, has spark, i can hear the fuel pump while it is trying to start but its silent while at the on position. does the CAS control spark, like since i have spark the CAS is working fine? and what does that round covered terminal go to?

The fuel pump only should work when the key is to start and not in the on position unless the engine was running. The CAS is responsible for sending input information to the ECU so it knows when to spark and inject fuel. Not sure which plug/round covered terminal you are talking about. And is the S5 engine a JDM or USDM?

JDM with the knightsport turbo, cause i read that the CAS had to be the s4 and i had to use the wires off of the original car and CAS or it wouldn't work. But since I am getting spark should I not worry about that?

The fuel lines are hooked up in an opposite manner relative to the U.S. versions. So your feed line is closest to the firewall and the return line would be farthest from the firewall just in case you forgot to take that into account.

wait so reverse them on the engine itself? cause I have the one off of the fuel filter going to the bottom rail and the top rail goes to the return line.

On a U.S. version the return line is closest to the firewall. If that is how you have it then it needs to be changed.

k so i go from the fuel filter to the upper rail an then take the return off and nothing comes out, if i run the line from the filter to the lower rail and then remove the line on the return it blasts out fuel so my flow is filter>lower rail> upper rail> return, that makes it usdm?

and also what is in control of making the injectors fire? and how can i test them?

cause everything seems to be working but it just cranks fast and nothing it doesnt even start to fire up.

My fuel rails are set up the same as yours, and my engine is a JDM. Where did you get your engine from? If it has the N374 ECU then it is JDM. Did it come with this N374 Redom ECU?

The ECU controls the injectors. If your injectors are not working, then there is something wrong with your wiring or the injectors are screwed. In your case, it seems like the wiring is messed up. Are you using a harness that your S5 engine came with or the USDM N/A harness that was in the car?

I got the engine from a friend who said he ordered it from a JDM supplier. and yea it has a redom N374, and the harness is from another car but its a USDM harness, and I have the injectors running right off the ecu nothing spliced or cut and i marked what went where when i removed the plugs. how could the wiring be messed up? grounds possibly?

What do you mean by this??

I wasn't sure if you had moved all of the pins to their correct positions at the ECU connectors or not. It would be SO much easier for you to just use an N332 or N333 ECU.

like the wires that come off of the injectors runs into the loom and goes into the ecu the only wires i had to splice was the coil wires, so i dont see how my injector wires could be hooked up wrong?

The S5 JDM TII N374 ECU and S4 USDM TII ECU's (N332 and N333) have different pins at the ECU, though. I thought there would be much more modification of the harness ECU connectors.

If the rats nest on the car which houses the hard fuel lines is off of a USDM car then the connections would be the same as any USDM car. If the return line was disconnected and placed inside a jug and the fuel check connector jumpered and key to on the fuel would come out in copious amounts.

One thing you might want to do is to check the ECU pin positions that relate to the fuel injectors. W/key to on all four of them should read 12 volts. Do yours? Pin 3W front primary, 3X front secondary, 3Y rear primary and pin 3Z rear secondary.

ok so all the 4 wires for the injectors have 12.02v, and when I undo the return fuel line it shoots out a lot of gas. now the question is if my engine is JDM or USDM considering it came with a RHD harness and the oil filter has zero english writing on it including the spark plugs i would say JDM. now the ECU and harness i am using it outta a USDM 1991 vert turbo swap, but im using the injectors that came with the car, should i try swapping injectors?

So, you have a USDM S4 GXL chassis, a JDM S5 TII engine, a USDM S5 N370 ECU, and a USDM S5 TII harness, and S4 460cc N/A fuel injectors? -- WHY?

You're making things WAY too hard on yourself.

no the only thing s4 is the car, and the under the dash harness. ecu, injectors are s5 Tll and the engine is jdm s5 Tll

You stated you have spark. How did you test this? Do you have a spare CAS to play with?

i pulled the wires off the plug and checked for a arc, and when i start it just cranks away and does not try and start at all. so the computer, wires and injectors all came out of a running car that that just recently blew its engine. so I know the injectors are good and the ecu was good. I have gas flow, and spark. is only the ECU responsible for the injectors or anything else? and yea i have two extra CAS

Then unplug the CAS and connect in another one and spin it w/the key to on and listen for the injectors (primary) to click. Before doing this disconnect the two wire plug from the leading coil and the two plugs housing six wires from the trailing coil so the coils don't fire and drown out the sound of the injectors clicking.

save urself time and just buy a standalone setup. also nice sig, kablam was my favorite effin show

how loud will the injectors be? and I plan on going MS down the road but $$$ is a issue and im working with what I got :)

Loud enough to hear if there aren't any other competing noises being made.

k so i used the s4 wires for the CAS and the s4 CAS and i can hear them!!! anyways i need to obviously now set the timing, is there a good link i can read for timing or just a good explanation?

k so i lined the needle up with the yellow mark, and the bottom dot on the CAS with the little buldge mark on the CAS and got it put in.

So i can hear my primaries clicking, i have fuel that sprays out the return if i undo it, and spark coming from all 4 wires. still doesn't even want to attempt to start

k so now none of the injectors or clicking, if i were to run a injector off the wrong injector wire, like out of firing order would it hurt the injector? or does this sound like a wiring problem?

Did you say you used an S5 CAS. If so then I believe there is a difference between the S4 and S5 CAS as the S5 has a ground shield incorporated in the CAS wiring to the ECU while the S4 does not.

I tried s4 and s5 CAS and I'm using the original s4 wiring to the original plug under the MC and main relay and I have the 4 wires from the dash harness wired into the 3 wires on the s5 #3 plug

Bump

But how are you taking into account the ground wire necessary for the S5 CAS? Do you have the Red wire and Green CAS wires spliced together that connect to pin 3H of the ECU?

Yea the wires are spliced together, red blue to s5 3h r, green to s5 3G w, white to s5 3e L. Now there is a ground wire wrapped around the outside of the s4 wiring I am using does that need to be connected to something? And looking at the CAS they both seem to be exactly the same.

The ground shield should be grounded.

Red wire from S5 CAS is connected to the Blue wire of the S4 Emission harness.
Green wire from S5 CAS is connected to the White wire of the S4 Emission harness.
Both of the wires above, S4 Blue and S4 White are spliced together and go to pin 3H.

White wire from S5 CAS is connected to the Green wire of the S4 Emission harness and this goes to pin 3G.

Blue wire from S5 CAS is connected to the Red wire of the S4 Emission harness and this wire runs to pin 3E.

The SHIELD wire at the CAS plug should not be grounded there. IT is already grounded on the other end of the SHIELD.

Easy to check if is grounded. Just meter on ohms and one lead to a known gnd point and the other to the shield at the CAS plug. Should show way less than one ohm.

That said, even if you grounded it at both ends or no end the CAS should work just fine. Not recommended but it should still work. It's just a SHIELD to prevent emi. Right? right.

Got spark, got fuel, timing is in the ball park.......................bad compression or bad apex seals causing that lack of compression........................or pull start the thing if you KNOW you have fuel and spark. Not my way of doing things but will work if spark, fuel and timing are right.

I think it wasn't grounded at the ECU end, but may be wrong. In any event, I remember recently a poster had an S5 w/o the shielding being grounded at the ECU end of the harness and his engine had no spark , but after the shield was grounded at that one end things worked as normal.

When you say wire from CAS to emissions harness do you mean the first clip two inches from the CAS or the plug down right next to The steering column?

because there is a ground wire around the the section of the 4 wires that can be removed from between the CAS and the actual car harness and that ground wire is shared with another plug down off of actual harness, so I know what way that section of wires goes since they share the same clip ends and can be plugged in either way.

and is this right or wrong?

"Start with the S4 plug thats in your car find the 4 wires for the crank position sensor and put the red and blue wire together and connect it to them 3H pin green to the 3G pin white to 3E pin on the S5 plug "

At the CAS itself. You would have the next connector that's in line to match wires from one harness to the other. So if you have a plug that has a Green wire, a Blue wire, a White wire and a Red wire then they match up color wise at this second plug. And on the S4 harness's involved the CAS plugs into the Engine harness first and then that plugs into the Front harness. So when I said "Emission harness" I meant to actually say Engine harness (the S5 wiring only uses the Emission harness).

So I want them to match up color wise at the first plug right at the CAS and also match up color wise down where it meets the harness, and then wire it up like you said into the s5 harness?

The Red wire from the S5 CAS does not match up w/the Red wire of the S4Engine harness. It was already pointed out how you should wire it. Furthermore, as an example, the Ne signal on an S5 ECU has a Blue wire connected to it and only one wire and again, this wire is the color Blue. On an S4 ECU there are two Ne signals (not one as there is on an S5), one w/a Red wire and the other w/a White wire. Now if the S4 uses a Red wire and a White wire for the Ne signal but the S5 uses only the Blue wire wire then you cannot connect like color wires because you are mixing signals. Okay? So you have to keep Ne to Ne and G signals (two of them) to G signals.

Red wire from S5 CAS is connected to the Blue wire of the S4 Engine harness.
Green wire from S5 CAS is connected to the White wire of the S4 Engine harness.
Both of the wires above, S4 Blue and S4 White are spliced together and go to pin 3H.

White wire from S5 CAS is connected to the Green wire of the S4 Engine harness and this goes to pin 3G.

Blue wire from S5 CAS is connected to the Red wire of the S4 Engine harness and this wire runs to pin 3E.

Another thing you might have overlooked is if fuel flows w/key to start. You already verified that fuel flows w/key to on but not key to start. At the Circuit Opening Relay the wire in the top row far left should have voltage w/key to start. If it does not then it needs to be spliced into the wire that goes to pin 1C.

Sorry to interrupt... But this is all insane. All of these problems could have been avoided had you swapped over the S4 throttle body with TPS, front cover with oil metering pump, N/A wiring harness, S4 TII fuel injectors, N332 or N333 ECU, N318 AFM, N318 boost sensor, water pump and water pump housing, and clutch fan.

This is more wrenching than wiring. Which is what you're better at. You said it yourself...