DiscoQuinn

So I'm putting an S4 N/a with 5 speed into my previously carberated Corolla.

Anyways, stock S4 ECU, I have 12v to the ECU but looking at the diagrams I can't figure out:

-Switched power feed to the ECU
-Proper wiring for the ignitors
-ECU feed to the fuel pump

I'm sure there is more. The car is almost ready to run, ARGH!

HAILERS

The ECU does not feed the fuel pump or have anything to do with the fuel pump on a series four.

Switched power to the ECU is from the Main Relay to pin 3I a black/white wire on the stock car.

Ignitor wiring............it's shown in the wiring diagrams like the one shown below. The lead coil assy gets switched power on the black/yellow wire from the main relay, and the trigger wire is the Green/Yellow wire from the ECU. As in.....there are but two wires for the lead coil assy.

Seems you might just have the coil assy's with their electrical plug and have no mating plug going to it from the ECU as a normal car would. So maybe your wondering which wire from the ECU goes to which pin in the connector on the coil assy's.

Like the ECU pins 1X, 1U and 1M go to the Trail coil assy. So maybe your asking which pin in the trail coil assy elect plug does 1X go to and which pin in the connector does 1U go to and the same question about 1M?

If you look at the electrical plug for the trail coil assy on page 50-23 of the wiring diagrams, youlll see the trail coil assys electrical plug designated as F-35. Almost all the electrical plugs on the diagrams are viewed from the WIRE side of the connector. In this case F-35 is the plug on the harness side (not the connector on the trail coil pigtail).

So say your looking at the trail coils elect plug on its pigtail. And your looking straight into the pins on that plug. Then on the top row you'd have the wire from 1U and next to it the wire from 1X. On the bottom row you'd have on the left the wire that feeds the stock tach and next to it on the right the wire from pin 1M.

This stuff can't be done/described online. Takes too long for no gain. Gone

And just in case............the injectors are not fed power from the ECU. The ECU just puts a gnd on the injectors to pulse them.

DiscoQuinn

My Lead igniter has 3 wires?! a two pin connector with a second one pin connector hanging off of it (black connector). The coils were donated and are Rotary ones, but they might be from an FB or FD? Maybe a T2 FC? Unsure, but they look basically the same.

My crank angle sensor and both igniters are wired up just like the diagram, I even used a shielded wire for the CAS, but when I turn the motor over I don't even get spark from the leading coil? (plus all of the previous harness to the injectors etc. )

I even put 12V to pin "G" with the neutrel start switch just to see if that would help, but nothing.

frustrating as I've fed the engine fuel, it cranks with good compression, but no spark. sooo close to running! No one local is able to swing round and have a check on my wiring. boo.

Does the fuel pump just run 12V of switched power constantly?

With much thanks,

~DQ

DiscoQuinn

Hurray for spark!

So the 3I pin was the solution for spark, now just need to check if my injectors are dumping fuel. Pull the clips and see if the light green wires have a switched 12V, then crank it and see if the ECU is doing it's job?

Can I just run the fuel pump on a switched 12v?

Compression + spark, now just need fuel.

HAILERS

Yeah. Key to ON and pull the small connector off the ECU and the light green/white, light green/black, light green/red and plain light green should all have batt voltage IF you've fed the injectors batt power off some source.

Run the fuel pump off some switched power..yes.

yomomspimp06

iTrader: (4)

and don't forget to throw up some pics

HAILERS

If one of the THREE wires on the LEAD coil assy has a single bullet connector............that wire is a diagnostic wire for rpms and gets connected to nothing. If you gnd it then the coil won't work at all.

DiscoQuinn

Awesome Hailers!

Thank you. I will update this thread with in the next day with some photos and hopefully video of it running.

DiscoQuinn

So, it runs! But there is still an issue. We had to open the injectors manually to get fuel into the engine, the car will not start on it's own, prime them, plug the ECU back in, start the car and keep it revving with the throttle, otherwise it dies out.

I'd upload video, but YouTube is doing maintenance right now. :/

HAILERS

The problem is probably related to how the START sequence happens.

During START the afm is NOT used for fuel on a normal stock RX of your vintage. During Start, the ECU uses the start signal from the start circuit to determine that your starting the car. I think that is on pin 3B, a blue/black wire on a stock series four. In other words when you turn the key to Start the power goes to the starter solenoid but also goes to pin 3B on the ECU and FYI also to one of the two coils in the Circuit Opening Relay (to cause the fuel pump to come on).

So the ECU sees your starting the engine on 3B. Then it uses an internal fuel map for fuel delivery instead of the afm. It also takes into consideration the water temperature as to how much fuel will be injected. That signal comes from pin 2I from the water thermo sensor on the back of the water pump housing.

It uses this internal fuel map until the rpms get over something like 500rpm, then the afm is used for fuel delivery.

Lots of bad things can happen if the ECU sees the start signal but not the water temp signal. IF it has no water temp signal, the ECU defaults to a fully hot engine of 176*, which in turn means the amount of fuel delivered will be much too little for a cold engine.

Or lack of seeing the batt voltage on 3B when your starting a cold engine will mean the afm is used for fuel during your start and that results in too llittle fuel if the engine is cold. The car can be started but will be very difficult to do so.

I'll add the chart to this later since the attachment device on this thead isn't working right now.

HAILERS

Chart

I'd make sure 3B sees batt voltage anytime the key is HELD to start. I'd also see if the pin 2I is seeing the water thermo signal. You should see approx a half volt when the engine is HOT, confirming that the signal is being seen. If the engine is HOT and you have a figue like 4-5vdc on 2I , then the signal isn't getting to 2I from the water thermo sensor. On a cold engine you'll see a figure like 2-2 1/2 volts or so. The plug has to be on the ECU and you backprobe 2I to read it. You can't just remove the plug and read the 2I with it off the ECU.

DiscoQuinn

I'll take a look at that today.

Here is that video from last night

http://www.youtube.com/watch?v=4YrFVkxhsnY