Can anyone veryify the plugs for me at the ecu.

Here is how I have it set up.

Three yellow plugs that go directly into the yellow connections at the ecu,

one black plug that goes into a black box attachement on the ecu labeled control unit

Two white plugs two two white connections nearest the fire wall

Two blue plugs to two blue connections near the ecu

One black singled wire with grey spots that has 12v
and A black doubled wire with grey spots that has 0v
both sets connected together on a stud that runs off the ecu with a nut

And last but not least the ecu bolted to the ground.

Oh and a black wire with yellow spots with a plug on it that doesn't connect to anything but can be used to turn on the radiator fans.

 

bump

 

okay I tested resistance on each injector and there is exactly 13.8ohms of resistance on each fuel injector. Can anyone tell me where the injector recieves its power is it from the egi fuse?

I grounded both primary injectors and each one will spray. But cranking the engine over the injectors wont spray. I don't know what the hell is going on to be honest with you.

With the primary injector clips plugged each wire will produce 12v, with it unplugged it will produce 12v on one side and 0v on the other obviously since no current is passing through both points unplugged.

Is there some sort of firing trigger the injectors receive, maybe through the coils? Does the ecu then get this message to ground out the injectors.

The only possible solution I can think of is the (ecu) or some sort of (wire) that is tied into the ecu to allow the injector to ground out, but what?? Which wire???
What are the chances that the only portion of the ecu that went out are the injectors points, yet the rest of the parts on the car work fine?

There has got to be someone who can tell me exactly how the injector operates and recieves its signals on the FD3S.

 

This is weird, My friend has the same issue all together. I came on to 7club tongiht to find out some info and here it is. Don't feel left out, He has the same no spark issues. It was his CAS assembly. He would get spark for stock ecu but not his AEM EMS. Ordered new cas assembly, arrived, installed, now no fuel. What ecu are you running?

Btw, thanks to all who posted this for him, no I have some data to collect. Thanks again.

Ty

 

I fell out of the discussion - haven't been online much lately...



The ECU would normally provide ground to open the injectors. If the injectors open when you manually ground them, then they're functional and getting power via the B/Y wire. The issue lies between the injectors and the ECU, unless the ECU itself is fried (and not grounding the injectors at all). I think it's a short in the harness.

You could bypass the harness completely by soldering in separate wires to replace the injector ground wires, but the entire harness seems suspect if you're having problems like this. I'd replace the whole thing, at least as soon as you get a chance.



So you tested the pins on the harness connector, right? Not the pins on the ECU itself. You should get ~12V on all four pins with the ignition switch turned to "ON" - 4Y (LG/B), 4W (LG/R), 4Z (LG), and 4X (LG/W). This is with the multimeter hooked up between the pin to be tested and any ground.

For reference, the ECU doesn't provide power to the injectors. The ECU switches ground to the injectors to open them - the injectors have constant (unswitched) power via the B/Y wire. Testing the 4Y, 4W, 4Z, and 4X pins on the ECU itself is meaningless.

 

There's really nothing special about the injectors themselves. Functionally, they're exactly the same as those found on any EFI engine. When the injector completes a circuit (has both power and ground), it opens, and remains open for as long as the circuit is complete. Whenever it doesn't have power and/or ground, it is closed. Like most EFI systems, the FD design has the injectors constantly supplied with power (the B/Y wire always provides ~12V whenever the ignition switch is turned to "ON" or "START"), and the ECU selectively provides ground to each injector to open it whenever it deems fit.

The logic that the ECU uses to determine when to open (and for how long to keep open) the injectors is beyond the scope of this discussion.


The injectors all receive ~12V via the B/Y wire, which comes from the EGI main relay.


Nope. The injectors are open when they are grounded by the ECU, and closed at all other times. The injectors receive no separate signal. Also, the injectors have nothing to do with the ignition coils.


The ECU has two primary tasks in keeping the engine running - open each injector at the correct time (and for the correct duration), and then make a spark in the corresponding chamber at the correct moment. There's a hell of a lot more to the ECU, but if fuel isn't spraying into the chamber, then how will you be able to tell that every other function of the ECU is working correctly? The only way you can see that the ECU is fried is by looking at its "output devices" (injectors, solenoids, relays, etc). If the device is working, then the ECU is performing that function correctly. Still, there's nothing to say that an individual function of the ECU can't stop working while all the others continue to work perfectly.

Regardless, I think yours is a wiring issue. Specifically, I think the harness got damaged somehow, and there is no continuity between the injectors and the ECU. Thus, the circuit cannot be completed (no ground available to the injectors), and the injectors are not opening, even though the ECU is still switching ground to the appropriate pins as it was designed to do.

 

So you cut a ground wire that runs from an injector to the ECU? You did this on one of the primaries, correct? As in LG/R or LG/B, right?

And by "probed the ECU at that terminal", do you mean that you hooked up the test light leads where you cut the wire to complete the circuit?

If you did this and got no light when cranking, it doesn't necessarily mean that the ECU is the problem. If the harness has been damaged, the circuit may still be open. The fact that the injector opened when you grounded the wire indicates that you must have continuity between the injector and the point where you cut the wire. The circuit could still be open between there and the ECU.


I'll have to double-check to be sure, but I think you have it right. In general, ring terminals are ground points.


Okay, let's test the harness again. Follow this procedure carefully:

1) Get out the multimeter, set to voltage (100V or similar - more than 12V).

2) Disconnect the harness from the ECU. This is the connector that I posted a pinout diagram of.

3) Turn the ignition switch to "ON" (not "ACC" or "START").

4) Now on the harness-side connector (male connector that the harness wires run into, NOT the female connector on the ECU itself!), locate pin 4W. The wire running to this pin should be LG/R (light green with red stripe).

5) Touch the multimeter red probe to this pin, and the black probe to a ground point (a nearby bolt threaded directly into the chassis is fine). You should see ~12V now. If you don't, the front primary injector is not being grounded due to a continuity problem in the harness itself.

6) Now locate pin 4Y on the same harness connector. The wire running to this pin should be LG/B (light green with black stripe).

7) Touch the multimeter red probe to this pin, and the black probe to a ground point. You should see ~12V now. If you don't, the rear primary injector is not being grounded due to a continuity problem in the harness.

8) Report your findings.

You could also test the secondaries (pins 4X and 4Z), but for now at least, make sure the primaries are able to complete the circuit. Otherwise, the engine will not start.

Above all, make sure you are testing the pins on the harness-side connector, not the female connector on the ECU that it plugs into. Also make sure you are on the correct pins. Double-check the color of the wire that runs to the pin being tested. Let me know what you find.

 

Dig Dug,

Got it! Well What is strange to me is that the wire that connects to the ecu inside the cab has voltage coming from the injector. If it was a cut in the wire than I shouldn't be recieving any juice from that wire inside the cab. And if the wire was grounding out somehow then the injectors would be spraying constantly.

I will try the tests out that you gave me that gives me great hope, and direction. My wife just got out of surgery so I'm still trying to get through that part. I will report my findings asap, Thank you so much for all the help Dig Dug it is greatly appreciated as for the others who have been helping me, god bless you!

 

If all else I might try just running an individual wire and solder it into the ecu wire and injector.

 

on digdugs last tests you need to have the injector it's self pluged into the injector harness. look it is not rocket science it is a simple circuit like a turn signal don't over think it. hope it works out. and when checking for ground you know you must hook the test light up to a 12v source right, ground to ground = no circuit

 

Well, what's the word?

 

Hey pimpin7, any updates on this?

 

Oh yeah sorry! My wife's post-surgery has been keeping me really busy lately. All the sudden I'm a housewife among other things. Anyhow since she can't help me with the cranking of the engine so I can test the ecu, I decided ahh what the heck I'll just take the whole ecu wiring harness out and clean it up since I can't do both things (cranking and testing). I really had to do this, something I should have done before reinstalling the engine.

There were a lot of toasty wires like Gadd had mentioned, and a lot of bare spots on most of the wires, just cracked from the extreme heat and old age.

What I did notice on one of the primary injectors was that after removing some of the heat shrinking material from an area, there was a bare spot on the wires, and both of these wires were touching together, but still does not lead me to believe that is the problem if that was the case the injector would just be spraying constantly, right? Furthermore, I found out both primaries front and rear, the wires were backwards. Not sure if that would make much difference I don't think the polarity of the wires makes a difference, you think?

Well anyhow I have been working on it the last couple of days trying my best to clean up the wires and solder fresh wire in its place in my spare time, heat shrinking and what not. Hopefully I can have it ready in a couple of days reinstall it and see what I can find out, as far as testing at the ecu.

I called mazda for a new harness, can you believe they want $950!

 

Thanks for making me feel more confident. I know it's just two wires to each injector, but damn thing is really biting me in the ***. Rocket Science is starting to look more promising, lol.

 

Power and ground wires to an injector were touching eachother? That's why the injector wasn't spraying - it's shorted. The injector is out of the circuit.

 

As much as I hope it will be the problem, it still doesn't explain why the other primary injector wasn't being activated. The wires on the other primary were fine. I tested continuity all the way to the ecu plugs and it was fine for all injector wires. It could explain,however, the reason for the ecu shorting out if indeed it did.

 

I would continue repairing the harness, put it back in, and try again. Make sure the injector connectors (hehe) are installed correctly.

 

Well It turned out to be the wiring guys and you were right. I pretty much repaired most of the wires sodlering and heatshrinking absolutely everything that needed it. Insured that all the wires were in the right place. Also I tested every wire for continuity, it was tedious, but in the end that was the problem, and the injectors are now spraying. Thanks so much for all your guys help couldn't have did it without you.

Special thanks to digdug and gadd for not letting me back down.