V8 Engine Conversion

Last updated: March 12, 2004

Editor's note: By posting this on hte iste I am almost certain to get flamed. However, the purpose of the site is to collect any and all info on the 3rd gen RX-7, even if it is not what I would personally do. It would be bad to lose any info on these great cars.

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From: twint78

this tutorial is not to tell u specifics of every piece like torque on bolts, specific wire colors.and on and on.this is too help you trouble shoot and making a v8 transplant easier.

ELECTRICAL:

wiring the LT1 into the RX7.

These (4) connectors are located behind the right side kick panel in the passenger compartment. They were formerly arranged in a row along the front side of the RX-7's ECU, which is now removed. The wire locations and color code are shown in the illustrations below. The yellow highlighted wire locations are the ones that we will be either modifing or connecting to the LT1's PCM. The IDs of the highlited wire locations are listed below the illustrations. The non-highlited wires are no longer needed, and we will not be connecting them to anything.

1A is a 10 amp fused constant 12v source into the ECU.

1B is a 12v source that is switched on thru the main EGI relay with the ignition switch.

1K is the lead that the RX-7's ECU grounded to bypass the fuel pump resistor at high boost levels.

1M speed sensor signal from the RX-7's instrument cluster (3E).

1T is the lead that the RX-7's ECU grounded to energize the circuit opening relay, which activates the RX-7's fuel pump (NOTE: this circuit needs modification to work properly with the LT1 PCM).

2B is the signal wire for the RX-7s tach.

3D is the wire that the RX-7's ECU grounded to activate the cooling fan relays, resulting in the "low" speed mode (activates fan relay #2 & #4 by grounding their "B" terminals).

4th connector nothing is needed.

Wiring schematic from dana at lt1350.com.(you must send your harness in to get it worked. he will put in resistors, relays, vats bypass, and label the wires you will need to hook p into your rx7.)

vss output

a/c ignition power

a/c

red alternator wire

engine temp

oil pressure

tach out

red-ignition

starter wire

battery hot

oil level

ses light

fan relay

fuel pump relay

this is a write up for a 94 lt1 z28 with a 700r4 electronic speed sensor.

i bypassed all creature comforts.i did not use a/c and power steering.

i bypassed the water temp and oil pressure gauges on the dash. i did this cause like most i use upgraded gauges and i wanted accurate measurements.

i did not use dana's oil and h20 temp and pressure wires, cause as i stated above i already use aftermarket gauges.

lets start with the VSS(vehicle speed sensor).

• there is an orange and green wire going to the stock speed sensor on the manual transmission of the rx7.keep the orange wire and get rid of the green wire.your orange wire is for ground and will be needed later, just let it sit inside the car.green is signal from the vss to tach and can be cutout.
• the lt1 pcm will have a vss out wire. and a vss sensor plug attached already. plug this into ur 700r4(4l60)'s speed sensor unit. this will now read vehicle speed and mileage.
• connect your rx7's vss in wire to the lt1's vss out wire.it will now read twice the engine speed.you will need to buy a digital dakota box sgi-5.

tachometer wire

• this one is easy. connect the one coming from the rx7's old harness to the tach out wire on the lt1's wiring harness.

the orange wire i told you to keep.

• u must ground this wire.it is the gauge cluster's ground wire.if this is not grounded nothing will read or pickup.

ignition

• take the a/c ignition power wire that is in the lt1 harness and connect it to your 10A fused constant in the rx7's harness.
• take the red-ignition wire and mate it to the 12v source wire on the rx7's wiring harness

starter

• there is a purple wire by ur o2 sensor connector that hangs.this will be connected to your smaller post on the starter.connect the other end that is labeled and run it to your ignition switch on ur igntion.it will be a black wire with a blue stripe. this will totally bypass having to use the clutch switch to start ur car and saves on wiring schematic headaches.
• run a battery wire from the battery post
• run a wire from the battery post on the starter to the fuses by your headlights where your battery used to be located.
• run a power wire from the battery post on the starter to inside the car. you will then be able to add a connector on it and splice it into 3 seperate wires.
• one for battery hot on lt1 harness and one for each blue wire on ur new fuel pump and fan relays.

relays

• each relay has a yellow wire and blue wire hanging.blue is battery.yellow is to ur fuel pump or fans.
• u can connect the fan relay to the fan wire on the rx7 harness.
• you will have 2 wires for the fuel pump.a fuel pump resistor wire and a fuel pump ground opening relay wire.i bypassed the resistor by grounding out the f.p. resistor wire.you will connect the yellow wire on ur relay straight to the positive on the pump's harness.tak the old fuel pump ground circuit opening relay wire and ground it.it must be grounded for the fuel pump to work.i put a on/off switch on it.this way i can turn the fuel pump on or off at any time.

service engine soon wire

• hook it into a light just for it.

red alternator wire

• run it into a small dash light bulb.run the other end into a 12v source. 12v ignition wire is a good source.
• it will come on and flash while cranking.the light should go off once running.if it does not do this then u might want to have your alternator tested.

things i got rid of.

• egr
• ac
• ps
• oil level
• stock water temp
• stock oil pressure
• the 2 gray connectors by your old battery location.
• clutch switch
• reverse light switch
• nuetral switch
• 1-2 switch

u can hook up reverse lights if desired.i didnt care so i didnt.but u can hook them up through the stock auto shifter in several ways.

sensor hookups

injectors

• all injector harness pieces are labeled.if facing the car, even cylinder bank on left, odd cylind bank on right.
• everything else is explanatory once this is hooked up.
• idle air control
• throttle position sensor
• opti sensor
• water temp
• 2 coil sensors
• maf sensor
• knock sensor
• oil pressure sensor
• o2 sensor
• map sensor
• vehicle speed sensor

ignition firing order

• the opti is up front behind the water pump and crank pulley.
• even side is from bottom to top.2-8-6-4
• odd side is from bottom to top.1-7-3-5 if you are not sure you can look at the side of the opti and see the firing order numbers.
• will have more in a bit.

TROUBLESHOOTING GUIDE:

1.  CAR WILL NOT TURN OVER,NO POWER? 

THIS IS A CHECKLIST TO GO OVER 

-WITH AN OHMETER MAKE SURE YOU RECIEVE 12V TO THE SPECIFIED AREAS 
-12V IGNITION 
-HARNESS POWER 
-KEY IGNITION 
-MAKE SURE YOU HAVE YOUR CABLES HOOKED UP CORRECTLY 
-MAKE SURE YOU HAVE YOUR ACCESORY POWER WIRE HOOKED UP CORRECTLY 
-MAKE SURE THERE IS SECURE ELECTRICAL CONNECTIONS 


2. CAR NOW HAS POWER, TURNS OVER, BUT DOES NOT START. 

THIS IS HOPEFULLY JUST A FUEL PROBLEM. 

-MAKE SURE YOUR FUEL PUMP IS HOOKED UP CORRECTLY 
-MAKE SURE IT TURNS ON. YOU WILL BE ABLE TO HEAR IT FROM INSIDE THE CAR. 
-MAKE SURE OF YOUR FIRING ORDER....EVEN'S BOTTOM TO TOP-2,8,6,4 ODD'S BOTTOM TO TOP-1,7,3,5 
-WITH A TEST LIGHT TEST YOUR INJECTORS HARNESS.PUT YOUR NEEDLE TO POSITIVE SIDE AND YOUR ALLIGATOR CLIP(GROUND) TO SIGNAL(GROUND) SIDE. 
- YOU WILL RECIEVE A PULSING LIGHT WHILE CRANKING OVER.DOES NOT HAVE TO SPECIFICALLY HAVE A BRIGHT LIGHT. 
-MAKE SURE INJECTOR HARNESSES ARE ON CORRECT INJECTOR.THEY ARE LABELED IT IS NOT HARD TO SEE. 
-MAKE SURE YOU HAVE CORRECT FUEL PRESSURE.A GAUGE IS 30 BUCKS AT AUTOZONE AND WILL HOOK RIGHT UP WITHOUT UNDOING HOSING. 
- YOU WILL HAVE AROUND A GOOD 40-42 PSI STRONG. 
-IF ALL FUEL PROBLEMS ARE GOOD THEN WE MOVE ON TO THE NEXT PART. 
-CHECK YOUR OPTI.TAKE THIS APART AND MAKE SURE IT IS MINT OR NEW.IF IT HAS ANY SORT OF RUST REPLACE IT. 
- IT WILL HAVE 3 BOLTS HOLDING IT TO THE BLOCK.THEN 4 LITTLE BOLTS HOLDING THE OPTI TOGETHER. 
- YOU WILL ALSO HAVE A LITTLE GEAR IN THE BACK. 
-PULL THE PLUG WIRE OFF OF THE COIL AND PUT THE BOOT CLOSE TO SEE IT PUTS OUT AN ARC WHILE CRANKING. 

3. I RECIEVE NO FUEL INJECTOR PULSE? 

THIS IS USUALLY THE OPTI SPARK.IT HAS A HIGH RES AND A LOW RES SENSOR IN IT.HIGH CONTROLS IGNITION AND LOW CONTROL RPM AND INJECTOR PULSE. 

-WITH A TEST LIGHT PUT THE NEEDLE END INTO THE POWER SIDE AND GROUND THE ALLIGATOR CLIP.TURN CAR ON.THE LIGHT WILL COME ON, IF THERE IS POWER TO THE INJECTOR. 
-IF YOU RECIEVE NO POWER CHECK YOUR IGNITION POWER WIRE ON THE HARNESS TO MAKE SURE IT IS CONNECTED. 
-YOU SHOULD HAVE POWER CONSIDERING THE HARNESS WAS TESTED AND PASSED,PLUS YOU POWER TO EVERYTHING ELSE.THE 12V IGNITION POWER WOULD BE THE ONLY THING KEEPING IT FROM HAVING POWER OTHER THAN BATTERY POWER WIRE. 
-CHECK TO SEE IF YOU HAVE SPARK 
-IF YOU DON'T HAVE A NEW OPTI YOU WILL NEED ONE NOW. 
-IF YOU HAVE A NEW OPTI AND STILL NOT RECIEVING PULSE, HAVE A FRIEND WITH A CAR OF THE SAME YR LET YOU TRY HIS PCM.OR YOU CAN BUY ONE FROM THE JUNKYARD FOR A 100 BUCKS. 

4. OK, I INSTALLED NEW OPTI. I NOW GET A PULSE.BUT IT POPS AND PINGS AND BELCHES? 

-PULL YOUR OPTI.YOUR TIMING IS OUT OF PHASE. REMEMBER THAT GEAR ON THE BACK I TOLD YOU ABOUT?WELL THIS GEAR HAS GROOVES ALL AROUND IT ON EACH SIDE. BETWEEN THE GROOVES IT HAS A FLAT SIDE ON EACH END THAT LINES UP. 
MAKES THESE FLAT PIECES ARE LINED UP ON THE BACK OF THE OPTI PLATE, AND IN TIMING COVER CORRECTLY.IT ONLY GOES IN ONE WAY. IT WILL SLIDE RIGHT IN, YOU SHOULD NOT HAVE TO SHOVE IT ON. 
-NOW WITH IT INSTALLED CORRECTLY IT SHOULD START RIGHT UP.

Jim LaBreck had all sorts of problems with Granny's conversion kit, after working very closely with them on the development of the kit and even loaning them a lot of his parts for their development efforts. Read the full thread

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