P0175 (Please Read Entire Post, Lots Of Crap Going Into This)

Have an 05 TJ 4L I6. Had a misfire issue when I bought in 2020, let it run until it started having major problems with the following: acceleration on the highway, idling rough, multiple turns of the key to start. When I first got it, replaced the starter and spark plugs (used autolite plugs like an idiot).

Recently with the issues worsening, I have replaced the following with the recommended part replacement:
-IAC valve/sensor
-MAP sensor
-TPS (back of throttle body)
-the little sensor connected to the intake
-all spark plugs
-spark plug coil rail
-fuel injectors
-O2 sensors

The most recent repair being tonight (the Throttle Position Sensor).

Haven’t read the fuel trims after replacing because my buddy who had the scanner moved, but before they were high, like -32% high. Plus it has constantly thrown the code P0175 (among other codes), so naturally I assumed it’s running rich which makes sense. All spark plugs are gapped properly and did extensive research to ensure I got the best ones that the Jeep wouldn’t have issues with.

Brings me to this post, I’m at my wits end with this hunk of metal, just want it to run until I move back to the mainland. It’s still throwing the P0175 code and isn’t running like it should, haven’t Road tested yet, it’s my wife’s vehicle so she’ll let me know tomorrow if the issues persist (probably with considering the code).

Any advice or parts you recommend I check are appreciated. Love all the TJ owners out there, but damn I’m never buying a TJ again lol.

Did check the fuel trims, they looked fine, based on the PSI for the year, was a little fucky because you have to jerry rig the gauge to read it. Plugs are brand new, properly gapped, usually the issue comes from not enough air, but everything connected to the throttle body has been replaced and it’s not the CAI.

hear said:

Have you checked your fuel pressure? Multiple key turns could be fuel pump or check valve related. I don't know how to diagnose high fuel trims, but are your plugs fouled like you're running way rich?

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JKP said:

What plugs are in it? For the coil rail, you can use reg plugs or double platinum plugs. Single plat cause issues.

Is the IAT sensor installed in the CAI?

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They’re NGKs I believe double plat or irridum can’t remember. The IAT sensor is in the intake hose shown below. Not sure what a CAI is.

JKP said:

You said "Did check the fuel trims, they looked fine, based on the PSI for the year, was a little fucky because you have to jerry rig the gauge to read it. Plugs are brand new, properly gapped, usually the issue comes from not enough air, but everything connected to the throttle body has been replaced and it’s not the CAI."

So what did you mean?

CAI is Cold Air Intake.

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Meant to say fuel pressure, my bad forgot I wrote CAI

ItchyDong said:

So it was throwing the P0175 code before you started blindly chucking parts at it? Your original post isn't clear.

Does it run good in open loop?

Are your O2 Sensors plugged in correctly? Not meaning are they plugged in. Are they plugged in to the correct connector?

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It threw that code as well as multiple cylinder misfire codes. All of which was explained and mentioned.

Has trouble accelerating so no it doesn’t.

Yes I plugged each new sensor into the correct bank based on info I found online, ref picture

I never blindly chucked parts at it, I started with spark plugs and coil rail because the misfire was the main issue. Then I moved to the sensors: MAP, IAC, IAT, etc. then checked fuel pressure at the injectors, thought it was the fuel pump and/or regulator, it wasn’t, so next logical thing was maybe the injectors were messed up, so I replaced those.

It runs better than it did originally but still has issues accelerating, rough idle where it drops 200-300 rpms sitting at a stop in drive, as well as bad fuel consumption (thus the rich code and rich fuel trims.

Have done some further research indicating it may be a vacuum leak. I’m going to send some pictures of things that look off or don’t make sense. Don’t know anything about vacuum leaks.
1. Random unconnected plug
2. Hose coming out of the top part of the engine unconnected
3. Vacuum line hose slips off very easily on right side near fuel injectors

JKP said:

Not sure on the connector, maybe underhood light?

The hose from the valve cover elbow goes to the airbox.

Clamp the vacuum hose.

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The air box is non existent because the old owner put some random CAF on it, so now it just hangs free. And I’ll clamp it up and see if it does anything

limitz said:

Before you throw any more money at parts, you should check out the PCM. That has resolved P0175 codes before.

[URL]https://wranglertjforum.com/th...sor-heater-circuit-voltage.65160/post-1190870[/URL]

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I’m leaning towards it not being the PCM because it only has 73k miles on it.

JKP said:

The hose that's supposed to go to the airbox is the fresh air supply for the crankcase ventilation. The rear elbow has vacuum applied to it. That's been sucking dirt in. I guess you could put a filter on it.

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Shouldn’t any dirt or debris just be burnt off?, may try putting a piece of cloth or make some kind of filter