2003 Grand Cherokee Injector Diagram
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Discussion Starter · #1 ·
Edit: 99 Wrangler I6 4.0.
I just changed my exhaust manifold and gasket, realized that I hadn't marked the two injector wires closest to the front.
I've researched this and the common solution is to check the wire colors. My problem is the injectors were changed by the previous owner and it looks like the wires going into the harness are all uniform color now. At least the two front injector wires are identical.
Is there any way you can tell while driving if they were mixed? I drove it about 80 miles today and the power is better than before (horribly torn up manifold). No CEL. I'm just worried about doing long term damage with this.
Are there any symptoms I should look out for?
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All injectors share one wire color for the positive but the pulses ground is a different color for each injector
All else fails they each go to separate pin on pcm
What year and which engine do you have
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I'd have to assume they are correct since it's running well. It wouldn't if two were reversed.
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Running ok Not that reliable as a engines with batch injection run fine
Remember timing of fuel air mixture into cylinder is by intake valve not timing of when injector fires
However sequential injector firing can make an incremental improvement
More then a couple owners with the 2.5 had an rpm specific hesitation/stumble that was cured by unreversing the incorrect connections of injector 3 and 4
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If you unplug one it should throw a code and say which cylinder is misfiring.
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Discussion Starter · #6 ·
All injectors share one wire color for the positive but the pulses ground is a different color for each injector
All else fails they each go to separate pin on pcm
What year and which engine do you have
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Sorry, thought my signature was set up. 99 I6 4.0. Can you test to the PCM with a multimeter or something? Both ground and positive are the same on both injectors, unfortunately.
I'd have to assume they are correct since it's running well. It wouldn't if two were reversed.
That's what I'm sort of hoping, but as my Jeep isn't in the best shape I'm not sure if what I feel is running well is actual well or just better than what I'm used to.
Running ok Not that reliable as a engines with batch injection run fine
Remember timing of fuel air mixture into cylinder is by intake valve not timing of when injector fires
However sequential injector firing can make an incremental improvement
More then a couple owners with the 2.5 had an rpm specific hesitation/stumble that was cured by unreversing the incorrect connections of injector 3 and 4Sent from my iPod touch using Tapatalk
I wonder. Would it harm the engine at all to just swap and check?
If you unplug one it should throw a code and say which cylinder is misfiring.
Oh, pull an injector wire, see what cylinder misfires, then make sure the wire running to it is the one for that cylinder?
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If you've crossed injector wires, it will likely misfire and have no power. If you've got no codes you're probably fine.
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Again not true many have run wuth injectors furing out of order with minimal notable issues as fuel entry timing into cylinder is independent if injector firing order
Which is why older efi systems commonky used batch rather then sequential injector firing much like the fuel from a carb cane to intake manifold same time for all cylinders
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Yes with a ohm meter and pcm harness unplugged east to tell which harness wires go from which pcm plug to which injector
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Discussion Starter · #10 ·
Yes with a ohm meter and pcm harness unplugged east to tell which harness wires go from which pcm plug to which injector
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Do you know where I can find a wiring diagram that shows which pin corresponds to which injector? I'm either not googling right or there isn't much on it to find.
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If you unplug one it should throw a code and say which cylinder is misfiring.
So...if you disconnect the cylinder #1 injector, do you really need to read a code to know which cylinder is misfiring?
Again not true many have run wuth injectors furing out of order with minimal notable issues as fuel entry timing into cylinder is independent if injector firing order
That's exactly right. In the original Jeeps with the 4.0L engine, the engine would run with no camshaft position sensor input. The ECM would "guess" the cam position (with a 50% probability of being correct) and the engine would run with all six injectors firing two strokes out of phase.
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Discussion Starter · #12 ·
Thanks for the help, everyone. My biggest concern with switching those wires was that something could go really wrong if they were crossed and I didn't want to risk it. From the posts here it was clear that it wouldn't hurt anything to just swap them and test. My engine is running noticeably better and I have a little more acceleration than before. I'll get some various colored electrical tape and label them all out.
Thanks, everyone!
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Imediate info go to connectors.dctools.com
Or join jeepslimited.com
It is free and once admin approves you joining you get free acess to downloads with pdf of fsm for most year tjs
Limited not umlimited which is a different web site
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Discussion Starter · #14 ·
Imediate info go to connectors.dctools.com
Or join jeepslimited.com
It is free and once admin approves you joining you get free acess to downloads with pdf of fsm for most year tjsLimited not umlimited which is a different web site
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Did and now I finally have a FSM for the Jeep. Thank you.
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Source: https://www.wranglerforum.com/threads/how-to-tell-if-crossed-fuel-injector-wires.2310490/
Posted by: greggjurriese0197545.blogspot.com
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