Cyl #1 Injector Power Issue!!!

[918_gsx]

Ok, I checked all the pins at the resistor harness. Pin for Cyl 1 is not showing power. To verify, I pulled all injector plugs and #1, when pulled does nothing. All the others when pulled kill the car. So, question is...How come I'm not getting power to #1 injector or the pin at the resistor harness? I've checked the ECU and no burn marks or leaks at caps. Code 41 was also pulled with diag test. Thanks guys.

 

[brownfinger]

I just had to replace my ECU a lil' while back. Right after doing so, It began running on 3 cyl. again. The ECU gave me a code 41. Inj. 1 was, indeed, fried. I think the bad ECU took-out the injector. Try a different ECU if you have one. My old one looked OK when I took off the cover, too, but one new ECU and one new injector later, and she's running good. Otherwise, it's your ignitor/transistor. But it can't be that, because then you'd be running on 2 cylinders. Only other thing is a bad wire.

 

[918_gsx]

That's what I'm thinking. But...where does the resistor get its power to get to the injector? I thought only ground comes from the ECU?

 

[brownfinger]

My mind is on other things... but I think that the resistor is in between the injector and the ground. Check the resistance of the injector. Mine read "infinity" ohms. It should have read about 2 or 3 ohms. My blown ECU gave me CELs of 21, 22, 23, and 41. 21, 22, 23 = CAS, CTS, and TPS. And the engine ran. The engine can't run without a CAS, period. This means the ECU is toast. After the new ECU, it ran great, for about 5 minutes. Then code 41 came up again, with a new CEL. I used MMcD to disable injector 1. The car ran no different. I pulled the plug on number 1, no difference. That's when my buddy probed number one for resistance.

It's just too much of a coincidence. Just like me seeing your thread title on the right-hand column while browsing the Hangout; just too much coincidence. I had a LOT of weird things happen that day, and they all seemed to be related. But they weren't. They were all just coincidences. The only direct cause-effect relationship between any two things that happened that day were that my ECU blew-up, and it took-out injector #1 when it did so.

With a VOM, probe injector one across it's two pins for resistance. If it's anything different than 2-3 ohms, start looking for a blue 450 and a new ECU.

P.S.: Nice wheels... Both my 1Gs sport 2G 5-spokes. You have good taste, young Padawan.

 

[918_gsx]

Haha, thanks man. The wheels were already on it but I wouldn't swap them out for anything, looks sexy. And yea, I'll be going out to check that injector in just a bit. I'm getting code 41, 31, and 12. I knew about 12 before cause the tranny shifts like as and has no 3rd or OD. But the Air Flow code and injector ones have me confused. It would be alot easier to figure out if I was getting power at the resistor for injector 1 but I'm not.

 

[luv2rallye]

The injector resistor for cyl 1 is blown (open circuit) which is why you don't see power at injector 1. Power goes from the MPI relay to the injector resistor pack to the injectors to the ECU (which provides ground when injector firing).

 

[steve]

The injector resistor for cyl 1 is blown (open circuit) which is why you don't see power at injector 1. Power goes from the MPI relay to the injector resistor pack to the injectors to the ECU (which provides ground when injector firing).

Exactly. All four of the resistors are connected to the power lead from the MPI circuit and then the other side of the resistor goes to an injector to power it.

The ECU then pulls down the other side of the injector coil to make current flow and fire the injector.

 

[918_gsx]

And this explains why I'm only missing power to just cyl 1 at the resistor harness?

 

[luv2rallye]

Yes, just the cyl 1 resistor of the pack is blown.

 

[Bud92gsx]

Like I told you this morning..Replace the resister pack..And that should fix you up..

 

[918_gsx]

But I'm not getting power BEFORE the resistor pack. I checked at the plug before it hits the resistor

 

[luv2rallye]

You said only pulling #1 injector plug killed the car while pulling the others didn't so you must have power before the pack for the engine to run at all (otherwise no fuel). Remember it's only a short ground pulse on one side of the injector (ECU does this controlled by the CAS). So it has to be either the resistor, injector, wiring, or ECU for only 1 injector to not fire (maybe CAS but usually more than 1 injector doesn't fire then).

 

[steve]

But I'm not getting power BEFORE the resistor pack. I checked at the plug before it hits the resistor

Then none of the injectors would work. Perhaps the MPI relay wasn't on when you tested.

 

[918_gsx]

No, when I pull the #1 injector wires, the car stays running, no change. I pull #234, the car will die. I'm looked for power BEFORE the resistor harness and there isn't any for #1 injector.

 

[steve]

The connector has one power lead that is connected to all four resistors on the resistor pack side. The other four pins are the outputs from the resistors back to the injectors.

It's possible that the wire to the #1 injector resistor is broken from the common lead to the resistor if your actually checking inside the resistor pack but if your checking the pins on the car harness side there is another problem. If you measure the resistance between the common pin on the resistor pack and each of the four other pins you should see about 6 ohms across each resistor.

As you describe it, you're measuring the voltage on all of the pins at the car side of the harness and not seeing 12v at injector 1's connector. That says that either the injector coil is open, the wire from the ECU to the injector is broken, the wire from the injector to resistor pack is broken, the connector at the injector is bad, the connector at the ECU is bad, or the ECU is damaged.

I don't remember off hand what the injector driver circuit in the ECU looks like. I can't remember if the sense function winds up putting 12v potential on the output pin of the ECU or not.

 

[918_gsx]

Thanks for all of that info. I pulled the ECU to check it out, I've got corrosion/leak in my ECU in the center