Just finished buttoning up my fresh fully rebuilt motor. It runs on the rear primary injector only, no NOID on front primary injector. so you can image how rough it runs running on one injector. voltage tested injector clips and i get .4v readings on both front and rear primary injectors(im sure thats the wrong readings)..I just know that if I unplug the front injector clip NOTHING happens and if i pull the rear injector clip, the engine dies out. just to keep in mind, my harness has normal wear and tear or a burnt, old, heated up.. the injector clips are good still but the wires on it are going..

upon countless harness and ground checking making sure everyhing is in the right spot, adding grounds etc, I use a friends Apexi PFC. This is where it gets weird... First start, Runs perfectly, no roughness, but only for 2 SECONDS, then dies out, and will not start again, only way to get it to start again is to unplug/replug the PFC entirely.. I've gone back and forth (for hours) between ECU's and checking that my grounds and sensors are correct.


My Question is. What should my next step be? should i replace, add, fix, my computer, or harness. I'm afraid if i replace the ECU the harness could fry it? both are very pricey, and I just became broke after this rebuild... I need to make sure my next step is correct..

mods:
fresh built, from pineapple racing sponsor 0miles
large street port
Block Off Plate Kit
single turbo w/ 3" straight through pipe 10psi
apexi PFC

 

Could be one of the injector wires are shorting out. I really hope you didn't burn out the injector driver on that borrowed PFC.

Injectors have 2 wires going to them. One is 12v switched, when you turn the key on you should get 12v all the time. The other is a switched ground, the ECU pulses that wire to ground to make the injector fire.

This can be relatively easily solved by doing continuity tests on the wiring from the ECU to the connector. With both ends of the wires unplugged, test for continuity and also test to see if there's continuity to ground.

Also, check the resistance of the injector itself to make sure it's not bad. Probably not the case, but worth checking.



Dale

 

Thanks Dale!
I remember seeing 12v coming from both primary clips, the sad part is I don't remember what ecu I had plugged in, I'll check both tonight and continuity through the injector wires.
-Just to be sure:
no continuity(or O. L.) in wiring= open/short
Continuity to clip = good
can there be high continuity? If there is continuity that means my ecu is toast, right?

I had plans of replacing the injector clips too.

 

New wiring harness is one of the best things you will ever do to your FD. It sucks to drop the money for it but man does it save a lot of headaches.