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Thread: Two injectors not firing?

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Posts: 11-15 of 15
2011-08-26 07:13:32
Ok explain to me what you mean. You mean you are seeing a weak voltage at the ecu connector from the injector. Without the car turning over you should be seing 12v at the ecu's #1-#4 injector wires, the wire that goes into the ecu thats grounded by the ecu to trigger the injector. With the injectors plugged in car not cranking or running.

If your testing for trigger how are you doing so and how are you determining its weak? We are talking miliseconds here that during cranking and idle the ecu is triggering each injector. Im wanting to know how your determining its weak.

Basicly do this. Take 12v supply and ground from your battery and touch the pins on each injector to trigger them and make sure they all click. If so then its a wiring issue, if not then its an injector issue. Ive seen the suby 520's go bad. Its fairly common for them to be bad and not want to trigger or get stuck.

If they all click properly doing that then move on to troubleshoot wiring. Again no reason the ecu should have a weak signal. All it does is ground the circuit. So if your ecu is having problems then Yes, check the grounds on the intake manifold and make sure they are all grounded and intact On b13's there should be four ring connectors bolting into two spots on the intake manifold. Make sure they are all bolted and secured and no broken wires.

Again this shouldnt be too difficult to figure out. If you have a wire problem you will either have no grounding of the injector to the ecu or no 12v or very weak or intermittent grounding or 12v feed. What your describing makes it sound like there is definitely a bad connection somewhere. Either from your spliced suby connectors or before that on the stock harness. You have already stated which ones are having issues so run the tests.
2011-08-26 13:04:26
-I get 12v across all injectors so I know the common 12v is good
-The injectors are brand new and I know they work, I have tested these by two ways. 1. using a 9v battery on a spare injector clip and they all click and 2. I have switched the clips from 2-4 to 1-3 and the problem stays with injector clips for cylinder 1-3.
-I get continuity all the way from the injector clips to the ECU harness
-Cleaned all the grounds and made sure they were not broken/cracked, even added a ground from the intake manifold to the drivers side shock tower connecting to the body ground.

Way I tested pulse:
Hooked up my multimeter to the 12v side of my battery and stuck the ground lead into my injector clips and cranked the car, I noticed I would get voltage though 2-4 but not on 1-3. I next tested to see if the ECU was spitting out a pulse so I then tested at the back of the ECU plug (with the ecu plugged in, injectors were not), didnt see nearly as much voltage from 1-3 at the ECU vs 2-4 at the injector plugs but I did get a little bit of voltage.
2011-08-26 18:26:46
then bad connections then. Trace and check the wires. Plain as that. The ecu is still triggering them just not a good enough connection to do anything.
2011-08-26 19:23:19
But im testing right at the back of the ECU, why would I be getting a weak pulse out of the ECU?
2011-08-27 05:49:44
Turns out its a bad ECU, worked fine before it was sent out to JWT... I have a bad feeling out how this is going to turn out.
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