So I am trying to get my car dialed in for the Hammy meet. Here is what is happening.

The car runs on 2-cylinders. Runs well and sounds almost normal. Only the back cylinders are working (3 and 4). I have spark on all 4. Injectors are not firing on 1 and 2.

When I disconnect either one of the rear cylinder injectors, the front ones (1 and 2) start working.

So, as is, with every injector harness plugged in, the car only fires injector 3 and 4. if I disconnect 3, then 1, 2 and 4 are firing. If I disconnect 4, then 1, 2 and 3 are firing.

What gives?

The car is a 02 WRX with SPEC C motor and ECU.

 

damn, sounds like its possesed. wish i could help.
hope it works out alex.

 

have you switched injectors for small stock ones?

have you rotated all the injectors?

 

wow, are you getting a different voltage from the injectors when 2 fire then when 3 fire? have you ohm'ed out all the grounds? Also, if you have just 3-4 plugged in can you get either 1 or 2 to fire if you unplug either one? just tryingt o isolate if it has to do specifically with 3-4 or if you can just run any 3 injectors at once. If the voltage stays the same when its running 2 or 3 and you ohm out even on all leads I would try another ECU, Mike has a couple

 

Ok, I figured it out. Funky yet exciting...

I knew that everything (injectors, all sensors and stuff) had one common ground. However, I did not know that not having something plugged in would cause a sporadic ground. In my case, since I am using a Mustang 75mm throttle body, I was not using the OEM idle control motor. I guess the idle control motor is a pass through circuit so when it was disconnected, there was a “bad” ground so the 1 and 2 injectors would shut off.

Go figure. Since I converted from TEC III, this whole stock ECU thing is totally new to me...

 

umm, yeah, that was gonna be my second suggestion,

 

Now I want to find out if this is the case only on my car or if all WRX's do that...