#1 injector won't spray...?

mossyOblack

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Joined
Nov 20, 2012
Location
hickory/newton
Mossy
Hickory
98 xj 4.0

OK this isn't making any sense... Finally got my jeep running.. But it sounds like a subaru lol..
Meaning its missing really bad..

Number 1 injector is not spraying..a far as we know..
Tested with volt meter.. 12.5 volts to the power side of injector... And getting continuity from the injector pin down to the ecu as far as ground goes.. So I should be getting fuel right.. Also was getting p0201...

What's weird is with the noid light hooked up to the clip number 1 is the only one that doesn't light up..

I thought to myself lets say that the ground wire was grounding out some where before the ecu.. Wouldn't I then have a completey open injector? Even more wouldn't the noid light stay lit up?


Changed ecu and no difference... I'm stomped.. Any suggestions
 
If you've not tested the circuit loaded you really cant say its a good circuit. I think i would hook the scope up and look at a wave form for the injector's and you'll have a pretty good idea of whats going on.


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mossyOblack said:
Jeep was running when tested
Click to expand...
My point is the continuity to the pcm really isn't confirmation the circuit is capable of handling the amperage requirements of the load. If a noid light wont light you know its either pcm ground source issue or a wiring issue, you've ruled out pcm lol

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the wiring harness came from a running jeep. (mine) and the pcm. got to be the ground now. how would the ground effect only 1 injector tho?
 
So your saying even though I have continuity between the ecu and injector ground wire doesn't mean that its sufficient enough of a ground to run the injector..?
 
userbmx1315 said:
the wiring harness came from a running jeep. (mine) and the pcm. got to be the ground now. how would the ground effect only 1 injector tho?
Click to expand...

all injectors get power from the same source, then each injector has its own pin to the ecu.. Which then grounds each injector according to when its suppose to pulse.. So its possible that particular injector wire somewhere in the harness is shorted.. which brings me back to saying..lets say it was grounded out somewhere.. Wouldn't that cause the injector to stay on since it is already getting the 12volts from the asd??
 
Exactly, secondly it could be a pin issue from the install. The video links i sent you will send you in a simple direction.
If you need wiring diagrams let me know. Like i said the best way to test it is a scope.

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mossyOblack said:
all injectors get power from the same source, then each injector has its own pin to the ecu.. Which then grounds each injector according to when its suppose to pulse.. So its possible that particular injector wire somewhere in the harness is shorted.. which brings me back to saying..lets say it was grounded out somewhere.. Wouldn't that cause the injector to stay on since it is already getting the 12volts from the asd??
Click to expand...
Yup but if it was open or unable to move the current the injector wouldn't do anything, neither would the noid light

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If the injector isn't working and noid light isn't lighting then there isn't current.

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But I'm getting current from the test... I'm so confused.. In getting power and ground but no spray... It won't even light a noid light... How is that even possible
 
Trying to say that if you have 12v on either or both sides of the injector connector and that injector is not working either the switch source (pcm/ecm) has failed or there isn't a ground source.
Your test isn't telling you if the ground source is there or not, its only telling you there is continuity between the pcm connector and injector connector.

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So if its telling me continuity is there... But not telling me if the ground source is there.. and I've ruled out ecu.. unless the second ecu had the same exact problem as the first ( highly unlikely) then wth... The only thing would be no signal from the ecu..
 
If you key on is there 12v at the control wire for that injector at the pcm connector? Is there a chance the pin is loose or worked its way out of either connector? That why a scope is nice you can see the failure.

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A digital storage oscilloscope allows us to watch voltages/signals/grounds with a very high sampling rate. I dont think your diagnosis will require one. Again check at the pcm wire that controls injector with key on for 12v. That would verify integrity of the wiring.

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Have you tried swapping injectors to see if the problem follows the injector ? I might have missed it but just throwing in my 2 cents
 
Baker said:
Have you tried swapping injectors to see if the problem follows the injector ? I might have missed it but just throwing in my 2 cents
Click to expand...
If the noid light dosent work that would rule out the injector

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