3rd and final 7

iTrader: (9)

ok so im doin my SE engine swap into my S i got the engine in, and bit and peices in the engine bay. i ve been puttin off doing the wiring for the front harness. so here is my questions.

nuetral switch, what is this for and how important is it to hook up?

water temp switch, where can i find it?

ACV relay, same as last?

clutch & cruise control, are these needed?

fuel pump, does this just go to the fuel pump wire

heat hazard, does this just connect to the HH wire?

ground, this branches 5+ times do i need to just ground this at 5 different places?

air con, there are 2 different wire for this do i need it, all i have is a heater in the car?

i found a Blg wire and i traced it back to the front harness and engine harness connection and it goes no where, its depinned on the engine harness side, con i eliminate this?

i have one more but the only way i know how to describe it is that a Red wire that goes into the ECU via the small connector goes to a gray thing about 2 inches long and there is another wire i think that is a Red blue wire that i labeled cruise conctrol i ll double chk though any way i dont know what this is for

sorry for some many question and but i want to do this right the first time!


Charles

Jeezus

iTrader: (4)

Neutral switch? is that like a clutch switch? if it is, then it is for being unable to start the car with the clutch NOT pushed in.

Ground, YES! 5 different places. I believe they are Firewall, Alternator, Block, Tranny and fender? dont take my word for it though.

Thats all i know of right now though.

Good luck with the swap!

3rd and final 7

iTrader: (9)

bump

trochoid

iTrader: (6)

Neutral safety switches did not come out until 87, don't worry about it, it cuts out the cc when the clutch is pushed in. You can also remove the cc control box under the driver's side bin, right next to one of the amps. Use all of the grounds. Water temp switch needed for the SE is the sender on the backside of the wp housing. Exhaust overheat sensor, don't worry about it. AC wires, no worry if the ac is coming out. Blg wire, no clue, dig out the wiring diagram in the 85 FSM. Same for the last wire listed, FSM wiring diagram.

steve84GS TII

Clutch switch is just for cruise control.As stated,clutch/starter interlock systems didnt appear until the 2nd gen.
Neutral switch controls AC cuttoff and probably CC,has no effect on EFI really.
The SE has two water temp sensors.One is a thermister in the waterpump housing for the ECU.The other is an on/off switch located in the lower radiator tank that controls the air injection relief system.
Exhaust overheat sensor isnt a bad thing to retain. It doesnt just turn on the idiot light when the exhaust temps get too high,it also cuts the airpump output,to quell the temps in the cats before they go nuclear and burn the car down.If there wont be any cats on the exhaust system,you can definately skip the sensor.If you install modern freeflowing cat,it will probably be OK to ditch the sensor.

trochoid

iTrader: (6)

Steve, let's argue, lol. There are 2 more temp senders. One at the bottom of the radiator for sub-zero start assist, the other is the iat, which is located on the left side of the dynamic chamger. If it fails, or the wires are broken, it defaults to a 72* reading for the ecu. The critical one is the one on the back of the wp housing. I f it's non[op, the engine will not start.

Good call on the overheat sensor when keeping the stock exhaust syste, like we a stil have on our cars.

The 12As have another temp sensor in the oil pan for the hot start system. Not sure if the SEs have one or not.

Rogue_Wulff

Ummm, trochoid, I thought the sensor in the oil pan of a 12a was for the sub-zero start, and the one in the rad was for the hot start.

steve84GS TII

According to my FSM,the radiator sensor is just to control a portion of the air injection system(relief).Im not sure if the SE ever came with the sub-zero system,but I was always under the assumption that the thermo sensor for that system was the one in the pan,behind the low oil level sensor.
The sensor in the intake should be the air temp sensor,which is also found on all later EFI engines,in addition to an intake air temp sensor in the air flow meter.

84RX_Se7en

The SE has a very large subzero start system. Has a resevior the size of the coolant overflow one.

trochoid

iTrader: (6)

Yup, you're right. I had them turned around.

3rd and final 7

iTrader: (9)

so basicly i can eliminate 50% of my wires

for the ACV relay wires splice into the relay on the S?

3rd and final 7

iTrader: (9)

another set of wires i found , speed sensor wire is this for the cruise control?

edit: i did use the FSM thats how i found the labeling for the wire so far.

brandon davis

iTrader: (3)

if the water pump housing sensor is bad or in op the engine will not start on an SE?

trochoid

iTrader: (6)

According to Doc, the SE will not start with a bad wp housing temp sensor. One of these days I should ask him why.

3rd and final 7

iTrader: (9)

sorry guys but i got another question but this more of a why question.

i was looking at the wiring diagram online here http://www.wankel.net/~krwright/files/manuals/1985_RX7_FSM/85RX7(50)Wiring_Diagrams.pdf

at pg 16 connetor b 32

there is a BY wire coming out of the ecu to the injecters to the coils and then to the condensor why is this?

is it b/c the coils is where the injecters spray pulse from?

steve84GS TII

Its most likely the primary power wire for everything.
The 2nd gens are the same way,they have two big black wires (one white stripe and one yellow stripe) that are a common + for the major stuff like coils,injectors and smog solenoids.The other wires from these various components are the grounds,which lead to the ECU.The ECU grounds each item as needed to perform the correct function.That way,the ECU only has to handle a small amount of current,and not the full 15-20 amps of power that all these items can consume.

The main power wires usually dont originate from the ECU,although they are clumped together in the same harness.They will usually be powered up by the big,main relay on the drivers side of the engine bay.The relay is hardwired to the fusible link box and is clicked on by the ignition switch.

If Im not mistaken,the igntion system on the SE is entirely independant of the ECU,with its own advance,retard and distribution system.The ECU might grab an RPM refference signal from the coil or dizzy,but thats about it.

3rd and final 7

iTrader: (9)

so do you think that it would be really be nessesary to includ these in the swap?

trochoid

iTrader: (6)

Since the connector B32 comes off of the trailing coil, and if I'm reading the diagram right, not one of my better skills, and it ties in the main relay, the ignition switch and the circuit opening relay, I believe this is the only part of the ecu that is actually needed to run the engine. It's the one that in the end, controls the fuel pump.

The rest of the ecu is for emmisions related operation. I suspect that if all of the emissions are removed, the fuel pump relay is modded to take it's signal from the trailing coil and or afm without going through the ecu, then the ecu can be removed.