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interesting 2.9L issue


Dave90ranger

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now this is going to be something that i hope i can get some help on. i have been having this issue for over a year now and have been tweeking, testing and verifying all wires, grounds and such as much as i can. been testing sensors and even replaced a couple just to test(yea i know waste of money but it rules it out and such).

now i have been having this random and intermittent issue where sometimes ill start my truck up cold (as well as warmed up) and my engine light will be on and will be idling around 500. now if i lightly touch the gas the light goes out and its fine but as soon as i let off, its back and returns to the 500 rpm running. now if i rev it up like full throttle and let off, it sometimes stops and everything is fine. sometimes shutting it off and restarting it will fix the issue and can be on my way.

recently i have taken off connectors and checked for corrosion but all have been good so far and still have the same issues. while doing this it acted up at work(where i was doing it in our shop since i had time to do it) and i decided to start doing a wiggle test to see if something happened, i had grabbed the harness from where the idle air control goes into(main harness basically) and that ended up causing it to change and then suddenly it was fine and couldnt get it to act up again while in the shop(figures :annoyed: )

now the other day i was going home from work sitting at a light in neutral ac on and such when out of the blue, just stalls instantly without warning. start it back up and sure enough, engine light back on and 500 rpm idle. shutting off did nothing and revving did nothing. had to drive it for a min before it was fine and working good. im hoping i can get a video of how it idles and everything soon when i can get it to act up. im also hoping to when i get some time when im not busy to do a KOER test when the light is on and see if i get some sort of code to pinpoint this issue.

any advise would be awesome and very helpful.
i have done a full tuneup to it, plugs, wires, cap and rotor, fuel filter, fuel pump, fuel regulator, O2 sensor, new IAC and before that cleaned my old one, new TPS sensor and before that checked my old one which was good. timing is spot on as ive recently removed the head to fix a broken exhaust bolt and leaking manifold gasket and checked timing a couple weeks after doing this and still spot on.

i am thinking i have a wire harness issue somewhere on the engine on the back but just dont have that much time to take it apart and check, also have no backup car either. havnt replaced the distributor or TFI just the cap and rotor currently but i dont think that would be my issue at this time.

sorry for the long post and thanks for any insight for this as it has been driving me insane for over a year so far and havnt had any change so far.
 


jhammel85

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Honestly, It does sound like theres a rubbed wire in the harness.

As much as it sucks, I think all you can do is work your way back from where you wiggled it. Try untwisting the wire loom and wiggling. I bet there's something wrong with the TPS circuit.
 

Dave90ranger

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yea i think its a rubbed wire somewhere in that area of the harness. i may have some time to check it this weekend. was able to take a video today leaving work on what it does and while driving so maybe i can post that in a bit, may not be helpful but still shows what it does. i just need to slowly uncover the wires and work my way back to find it like you said and find it. at least im making some progress on finding it compared to where i was a year ago lol.
side note, now i have a coolant leak since i fixed my ac and started using that i need to fix but its no biggy but still has to be taken care of asap.
 

Gilbee01

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I know you said you did a wiggle test a little while ago but from the sound of it I think it might have a vac issue.


-gil-
 

Dave90ranger

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Manual
i have a vacuum gauge on it currently from when i was messing with my other issue i fixed a while ago and i have great vacuum and its steady. that was my first thought but i have ruled that out. i need to take off the loom on the wiring and try to find a chaffed wire somewhere in the harness that i messed with. its just soo intermittent that its one of those you gotta constantly fittle with to find it which i really hate.
 

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