No spark after S4 13B swap
 

hey guys I just finished swapping an 88 NA motor into my 85 GSL...heres the swap thread https://www.rx7club.com/1st-generation-specific-1979-1985-18/13b-s4-swap-into-my-85-gsl-849136/

I am getting fuel at the main line and the Circuit Opening Relay (COR) clicks when I have the key to "ON" and I push on the MAF flapper door. So I believe the COR is wired correctly.

When I turn the key "ON" I can hear the MAIN RELAY click.

But no spark when I crank the engine and ground a spark plug at the shock tower...

--- from searching I've seen hailers says to check the engine fuse. Since I have an FB interior fuse I'm not sure if I have one like the FC.

--- I DO NOT have any tach movement when cranking... I wired it using the tach wire that was located next to where the FB coils were...is this a good source or do I need to make my connection else where

--- I would also like to make sure I am getting ground to my ecu, how can I test that?

--- I have not had a chance to OHM test my coils but I am going to assume they work since I bought them from a reputable member on this board.

What else am I leaving out, I charged my battery so its not that either.

the spark works like this....

in a stock FC, the CAS sends the rpm signal to the ECU which will then fire the coils.

the coils get 12v switched power from the main relay. the FB doesn't have a main relay, it i think just distributes coil power from the ignition switch (might depend on the year too).

so check for 12v at the coil with the key on. the other wire(s) on the coil are from the ecu.

the ecu will fire them if it gets power, AND sees an RPM signal.

so again, if you took a spare CAS and plugged it into a stock FC, with the key on an spun it, it should turn on the fuel pump, fire the coils and trigger the injectors. injectors you can hear click.

if you have nothing, then CAS or ecu is likely.
if you have fuel but no spark, then it must be something with the coils/wires/plugs

thanks..

i have no spare CAS :( any other way without removing mine? I may just remove it anyways just to double check timing...

Anyway to confirm grounds? How does the CAS get ground if all 4 wires send signals?

can i confirm the ecu is getting a TACH signal?

another thing.. in my wiring of the FC main fuse box...I only have the MAIN, Retractors and Head wired which is what was on my fusible links, what about the EGI fuse and others, do I have to run power from here to something???

you could just unplug the fuel pump and crank the motor, its not quite as simple, but it'll work

the CAS is grounded to the ecu, basically. i think its an AC voltage generator.

if you wanna "see" the signal, you can put a voltmeter on it and spin it

in a stock FC, the main fuse powers the main relay, which splits into like 5 wires. two of these (well the 2 we care about) go back to the main fuse block, and then they go do stuff.

you'll have to look in the wiring diagram, and see which does what, but there are two power wires for the motor, there is a black/yellow which powers the coils and injectors, and the black with white which powers all the emissions solenoids, and bac valve etc.

i'm not sure how yours is, but that's how a stock FC is. either way both of those wires get switched power

For simplicity while rough wiring everything I gave these power directly from the battery, could this be whats causing my no spark issue?

ALSO:

http://img143.imageshack.us/img143/3491/casof.jpg

http://img12.imageshack.us/img12/6298/wireharness.jpg

The reason I asked about the grounds is because I have a black wire that is crimed to the cas shielding wiring, Do I need to ground this? pics are above

TTT

Do I have to ground the shielding of the CAS? I dont see it in the wiring diagrams but in the pics above it is connected to a solid black wire, which usually indicates ground...

thanks guys, I'm really close, just need to iron these last bugs out

1. Check voltages at ECU and compare to section 4b of FSM. This will quickly tell you if something is not getting power.

2. check voltages at the coils. Remove the covers (like the one that says" L1 L2" on the leading coil) and measure the voltage between chassis ground and each of the coil terminals (+, -). Each of these measurements should be equal to battery voltage (~12v).

so you hvent run any wiring coming from the egi and the other? that gives power to your ecu and also you coils. take a look at this pic here everything in yellow, on the left you can see before you hit the main relay you have 2 that come from the battery thats the B on the lines up top. b/g comes from the battery into the m/r and then comes out as b/y and then that powers your coil. is this how you have it?

I ran a direct wire from 3J and put an in-line 7.5 amp fuse to the battery...

I have been busy and I will check the power at the coils today and report back, thanks for the help guys!

sorry dont pay attention to the circle there but the wiring coming from the battery marked in yellow not the ground leaving the relay but power leaving the relay going to the coil

12v to both wires at T coil, and continues to B/Y at condensor and the L coil, then my 12v goes to FEM-02 and connects to (2) wires that I pigtailed to my power wire. With key to "ON" I get 12v to all (4) injector wires at the ECU, and as mentioned I get constant 12v at 3J

SO power wise I'm good, I have a suspicion its related to my tach wire, since my tach needle doesn't move during cranking.

And I'm still curious about my CAS shielding and why it has a wire crimped to the shielding it self near the ECU connector AND at the CAS connection near the FE-02 connector

BTW--I did the ohm test on the CAS and I'm getting 155 ohms, which is well in the range. Have not done OHM test on COIL's but I belive they work...I'll confirm this though

how did all you guys wire the tach signal, I just made a conection at the Y/G wire that WAS connected to my 12a coil.

I really dont want to have to take the dash apart again, but If I have to then I will, but is their a simple connection that can be made in the engine bay?

Other MISC things,

I dont have my Air Bypass Relay wired in yet, this shouldn't matter though...

I dont have my LED check connector wired, 1A 1B 1D...

All my IGN 1 stuff is showing good power

I wired the start wire to the B/Y wire that runs from the Main relay to coils and FEM-02

sorry I didn't wire the start wire there, its wired to my COR for fuel during cranking....

the FB and FC are essentially wired the same. the FB has a wire on the - side of the Trailing coil that just goes right to the tach. the FC is the same except its on the "trigger" wire of the trailing coil.

the FC trailing coil is strange, there must have been some kind of hardware limitation when they did it. works like this. to fire T1, it fires the "trigger" signal, to fire T2 it fires the trigger signal AND a "toggle" signal to switch the coil to T2. so to fire T2 BOTH fire, T1 only the trigger fires.

thanks j9fd3s, I'll play somemore with the tach wire and see what I can come up with

for my tach i wired the fb tach signal to the Y/B of the fc trailing coil.

K, but did you use the connection that was at the FB coil, which is Y/G i believe? Or did you use other?

this is pissing me off....I'm going to redo my cas wiring... in one strait run to see if that fixes it.

There is no reason to pigtail any wires into my cas signal wires right?

i believe that i use the wire right off of the coil i shortened it but i used it, the tailing coil also fires up the fuel pump relay which in turns fires up the fuel pump. im not sure that the 12a had a fuel pump relay but it should i started with FI .

thanks 3rd and final, I did a search and found that electronics shop you recommended in north bay, I'm going to get my wire and do the CAS wiring correctly.

I also confirmed that you DO need to ground the cas shielding at the ecu, just the one end though...I guess its to dissipate the signal its blocking from the cas wires...

Was this ever resolved? I did a s4 swap in my ae86 and I'm not getting spark.

what do you have for fuse box and relays? did you swap over the FC stuff or did u modify the 86's power supply?