Jeff20B

iTrader: (13)

FC 6 port engine is already in. Runs with a carb. I want to try EFI.

I have access to a complete N326 ECU with harness and resistor pack out of an 86 FC. This car ran so I know the ECU and injectors work. My problem is I have zero experience with S4 NA stuff. So I have a lot of questions.

Should I even bother with the stock ECU?
I know I'll need the MAF, and the TPS is the narrow style.

What is the ECU pinout?

I got the ECU out of the car already. It had three connectors. I see two go to the engine harness and one stays in the car? I need all three right? Working on removing engine bay harness. What about the other one?

Is there a FAQ or easy proceedure to deloom the harness to get rid of all the useless emissions crap/rat's nest?

Jeff20B

iTrader: (13)

What I'm asking is out of these three ECU connectors, what is kept, what is looped or added a resistor (if any), and what is ignored?

Thanks!

Jeff20B

iTrader: (13)

Ok I think I figured it out. That third harness is for ignition. Right?

Jeff20B

iTrader: (13)

Never mind. I figured it out.

MrGoodnight

iTrader: (1)

Want to share for future engine swappers? The 3rd plug is for the ignition switch/power?

Jeff20B

iTrader: (13)

I'd like to, but no one seems interested in helping me. But yeah I checked the wires and it's for ignition.

turbo_dave

iTrader: (50)

Second plug on engine harness can completely be eliminated(that plug has a cew blue wires)as it is for fc wiper motor.Third plug on engine harness with two black/white and black/yellow are ignition power for injectors which power comes from main relay in a fc.all the rest leading,trailing coil,cas,circuit opening relay(optional) goes straight to Ecu.

RotaryEvolution

iTrader: (30)

yeah, because that's what everyone around here does.. the third plug is for the CAS, power feed, ignition out, knock sensor signal, power steering signals and a number of other non important items.

Jeff20B

iTrader: (13)

Thanks Ben!

I'd like to make a thread in the old school section detailing the swap, but I needed some basic info first, so thanks for that.

Now I need to know whether I can just leave all the unneeded wires not connected or ground them/add a resistor/add a 12V feed or what. Obviously don't need power steering and certainly don't need any rat's nest emissions solenoids etc in the REPU. I'd like to deloom/depin the unneeded wires and rewrap to simplify it all. Then throw in the FC coils, MAF, the variable resistor and MAP sensor somewhere, and call it good!

Jeff20B

iTrader: (13)

Wow, so I can just leave it off the ECU? Just run the two other plugs only? That'd be great!

RotaryEvolution

iTrader: (30)

no, he's referring to the auxiliary plug that terminates about 12" up the harness.

bosozo9

iTrader: (5)

i'm getting sick of my carb'd REPU and i would like to go efi one day also. i too have a complete s4 set up that i would like to install. would upgrading to rtek make it any easier?

RotaryEvolution

iTrader: (30)

no

upgrading to a standalone would.

Jeff20B

iTrader: (13)

I do have a MegaSquirt but tuning it would not be pleasant my dad or me. Plus my dad is kinda interested in the REPU if, IF I can get it to run reliably well like a stock S4 NA does so he doesn't have to put up with a carb. It's already got a stock S4 NA shortblock in it with just a Nikki and a modded manifold (they welded a 6 port 12A manifold to an RE-SI flange = crappy flow) so I'm looking for any excuse to learn how to make a stock ECU work in it.

I know the S4 ECU is dumb enough that a simple upgrade to a free flowing long primary exhaust won't require a retune (standalone). I can even keep the narrowband O2 sensor if I can get it out of the stock manifold. lol

I'll see if I can detatch the MAF (AFM?) from the airbox and stick a cone filter on it or something. I doubt the clunky air box will fit the small engine bay.

I have a Walbro 255. I've read here and there that you need an FPR if used on a stock S4 NA rail. Any truth to that?

Jeff20B

iTrader: (13)

Oh, the yellow translucent harnesses. These are not needed?

I'd like to deloom the harness and delete everything that is not needed.

By the way, I removed what I believe is the barometric sensor while pulling the harnesses. It looks very similar to what I believe is the MAP sensor in the engine bay.

The barometric numbers are:
N325 6208
E1T11371
Ring a bell anyone?

The MAP sensor numbers are:
N327 6217
E1T12071

I understand the reason for needing two pressure sensors in an EFI setup like this. One is atmospheric reference while the other senses vacuum and/or boost.

I also pulled the variable resistor when I realized it's needed.

Anything else I should pull?

RotaryEvolution

iTrader: (30)

the translucent harness isn't necessarily needed but there are a few things that would be helpful in it. i forget which series had which but i believe most had the n/a alternator charge wires in that bundle, as well as the coolant temp sender wire for the dash gauge. in that bundle is the wiper wiring, sub zero assist pump wiring and cruise control wiring which all that **** can get chopped.

i haven't ever really gone to lengths of putting an engine into another vehicle but mainly you should just try to keep the harness rather complete and find the ignition feed to the ECU and wire that up.

then there's ignition, all you need is to wire up the coil triggers and feed the black/yellow wires battery power off a ignition triggered relay. the n/a cars all had the CAS wiring that went along under the brake master cylinder so you will need additional leads for the ignition trigger circuits. this was kind of a rediculous setup since the CAS wires went from the CAS, through the firewall on the driver side, along the back of the dash and over to a connector near that translucent bundle and then to the ECU.

and the fuel pump, since the REPU had a carbed pump you will need to find an external FI pump and mount it below the tank. good news is it is already plumbed for a return line.

the transmission shifter will need to be chopped and moved about 4" forward, there is a writeup here on how to do that somewhere. i did it on a 5 speed swapped '74 and it worked fine but the shifter hole did still need to be notched slightly. the n/a 5 speed replaced the 4 speed stocker fine with no driveshaft modifications, even reused the larger REPU starter on the FC transmission. i'm not sure if you could get away with using the REPU tranny since the clutches are different, and the flywheel and counterweights slightly off. the s4 n/a transmission worked fine with the REPU clutch so theoretically it should work in the reverse order.


i had one person drop me a bag of wiring from a FC to wire it to a REPU, 3/4 of the wiring was chopped off so after staring at it for about an hour i told the owner to just start over with a fresh harness and don't be so handy with wire snips unless you know what you're getting into. get it all wired up and running then you can start trimming things off little by little, making sure everything you do is reversible and in small portions. when you get knee deep it can become overwhelming quickly and you'll be spending more time looking at pinouts than actually cleaning things up.

Jeff20B

iTrader: (13)

Wow, thanks man! Thanks for the info! I can update this thread with what the truck already has done to it for you or anyone else interested.

Ok so far the truck has a 1978 5 speed which has the somewhat taller 1st and 5th. I swapped this in for two reasons: 1) the old Cosmo 76 5 speed was scratching in 2nd and 3rd and the slider hub was very worn causing uneven wear of the throwout bearing/pressure plate spring fingers (making weird noises too). 2) the stock 1974 rear diff is geared 4.625 so it feels like 1st gear is a granny gear, 2nd feels like 1st etc, and 5th on those Cosmo trannies is pathetically low geared. By swapping to the other low mile 1978 tranny, 1st and 5th are actually usuable, and the other gears are kinda close ratio so it should drive a lot better now.

As for whether or not a modern 225mm S4 NA flywheel, disc and pressure plate are compatible with an old school ribcase tranny? Absolutely they are! It fits perfectly in a 78 tranny and in my other REPU which has a 1976 Cosmo 5 speed and an S4 NA assembly in a set of nitrided R5 irons. It's all compatible. Don't let Racing Beat fool you. They tricked my friend into purchasing one of their old school 215mm light steel flywheels and clutch set for his REPU, probably to get rid of their old stock. After discovering that, I wasn't too happy about it. So here we are; both trucks have S4 NA flywheels and 225mm clutch setups.

Oh and one more piece of information re clutches, my rotary MG Midget has an actual REPU 4 speed tranny due to fitment reasons, and low and behold it has a 225mm pressure plate! Gasp! Turns out it uses the same or very nearly the same bellhousing from 74 to 78. And 225mm fits just fine!

Jeff20B

iTrader: (13)

Yeah, I got aquainted with how weird the harness are set up. Removing the main engine harness was not very fun. All wrapped up around the other harness and stuff. Glad I don't need to worry about dash gauges, subzero, wiper motor etc. The alt wires are already in the truck, as is the fuel pump wiring etc.

This sounds like it will actually be kinda easy. Just reconnect the ignition harness wires I had to cut, and then run everything out to the engine bay, then hook up only what's needed.

I have a new Walbro 255 external pump. Is that going to be too big?

RotaryEvolution

iTrader: (30)

i did call racing beat one time about an upgraded clutch and they told me the same thing. so i dug up some n/a clutch discs i had laying around and the input shaft splines are all the same on the non turbo trannies/engines and the clutch diameters work without interference. i threw in a puck clutch from an s4 n/a into an RX4 and it worked just fine, which also should have worked for the REPU.

the walbro will work but it will make it run a little on the rich side, the walbros tend to raise fuel pressure to between 50-60psi static off the pump and about 45-50psi after the filter.

Jeff20B

iTrader: (13)

All I had to do was grind out some casting flash in the starter hole to use an S4NA starter in the MG. It's narrow enough to fit with just 3mm on either side between the frame rail and gearbox. A bigger starter like anything 85 and older would not even come close to fitting.

This worked so well I did it to my REPU's bellhousing and now I have an S4 NA starter in it too. It seems to crank pretty fast. Must be the gear size vs the smaller sizes in earlier starters.

You may think the REPU starter is big and torquey due to its size and the small gear providing greater leverage, but I find the FC starter spins the engine faster, or at least it's fast enough for my setup. Plus it sounds like a stuck pig, which is kinda funny.

Thanks for the info about the walbro. Perhaps that's why I can't get the pressure lower than 5psi on a Mallory 4309 to run a carb. Maybe I need to add an EFI pressure reg to bring it down to 43 psi before entering the mallory? I'm trying to get 2.5 to 3psi to run a Nikki with eventual blow through aspirations. At the moment I had to add a second carb FPR that I trust and it works fine now. It was added between the mallory and the carb.

Cranking the pressure down ahead of the mallory has got to be the solution here, right?

RotaryEvolution

iTrader: (30)

i wouldn't bother trying to make an EFI pump work for a carb, it's going to move way too much fuel than it needs which will just overwork the system and circulate much more fuel than is necessary.

cranking the pressure up through a restrictor before it enters the carb should reduce the fuel volume and make it easier to lower the head pressure at the carb, yes. but i've never tried doing anything like that.

Jeff20B

iTrader: (13)

Hmm, I guess for the time I'm testing carbs in the GSL-SE, I could swap a carb pump in. But I'll do a blow through Nikki on a 4 port 13B later this year after all the 6 port stuff is done, and I was curious what I'd need to do to get it down to 2.5 or 3psi on a boost referenced regulator. Ever run into that problem like in the REPU for that guy recently?

Jeff20B

iTrader: (13)

j9fd3s informed me that I'll either need to use the switch at the bottom of the radiator or connect the two wires so it's always on at the ECU for closed loop. I'll have to connect them together.

He also said most other things can just be de-pinned. But yeah I'll follow your adivde and see about getting it actually running before doing drastic harness mods that are not reversable. Maybe I'll just unwrap, de-loom, then rewrap the known needed wires and try it with the known uneeded ones off to the side. Then if it all works, go ahead and de-pin the unneeded stuff. Sound good?

RotaryEvolution

iTrader: (30)

the '74 is running a holley red pump to a generic return system rising rate regulator 1:1:. base fuel pressure set at 10psi on the holley 2 barrel marine carb. it being a blowthrough and turbo i opted for more pressure near the max rated for the carb which is about 15psi before it may begin pushing fuel past the floats and dumping fuel into the carb. this is to be sure that the bowl is always topped up, the pump is also fed by a large reservoir style fuel filter so that the pump isn't straining to drain fuel from the tank outlet and acts as a mini surge tank to feed the pump.

for the wiring i would focus mainly on the main engine harness, the ampillary harnesses can be custom made, like CAS wiring with a shielded 4 wire audio cable. all the emissions stuff can be amputated but the main sensors should remain: CAS, AFM, ignition, pressure sensor, ECT, injectors and TPS. even the IAT isn't all that important, nor are the closed loop function sensors like O2. the stock maps are very close to maximized already, assuming there is no vacuum leaks in the system. closed loop only engages in a very narrow window and you likely won't be seeing it for even 1% of your run time. i almost never spend much time on closed loop function components on these engines because they rarely do much if anything at all.

Jeff20B

iTrader: (13)

That sounds like a good choice to use a Holley red. My red REPU has a big Carter 110GPH that I believe is rated at 8psi. It's the one with 1/2" brass fittings. I'll look into using this instead of the walbro as I believe the mallory FPR could actually handle it and bring the pressure down to 3psi which is the max in a Nikki before the float bowl level goes above the windows. You know, to keep it topped up like you said.

If this pump is too low, I also will have access to an MSD pump which PercentSevenC used succesfully on his DCOE blow through setup to get it down to 3psi. I just feel like the walbro is too big and causing my current setup to not get down past 5psi. He is now running an FD swap in his FB and could use the walbro.

Back on topic. The FC is gone now. I grabbed everything off it I thought would be necessary. I'll test this setup in my GSL-SE before trying it in the white REPU. I'll do the mods to the harness and temporarily bundle all the useful wires together, then bundle rest off to the side for later removal. Just gotta finish a long primary exhaust and swap an Edlebrock on it first! Thanks everyone.

Hmm, I might make my own shielded CAS cable...