2001 TJ misfire problem

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Nilka

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May 20, 2019
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Arizona
I have a 2001 wrangler Sahara automatic 167000 miles I started having the code p0442 thrown out fix the problem by changing the leak detection pump and the purge valve as soon as that happened I started throwing a p0306 code the auto shop changed spark plugs and used a fuel injector test drove it and got a p0300 and a p0305 changed the 02 upstream sensor and got code p0300 and p0305 replaced spark plugs to champion instead of auto light the shop put in and got codes p0300 p0304 and p0306 what could be causing so many misfires should I change the coil pack? Fuel regulator ? Any ideas
Also forgot to mention usually after clearing code I can drive for weeks with no code once I drive above 55mph is when I get the misfire codes
Also after 2 weeks of no p0442 it came back on last night.
 
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Nilka said:
I'I'trying to find the Schrader valve but no luck does this year and model come with one?
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They stopped putting Schrader valves on TJs sometime around 2001. Some of the 2001 models had them, others didn't. I had to get a fuel rail from a 2000 to put on my 2005, just so I could have a Schrader valve.
 
Chris said:
They stopped putting Schrader valves on TJs sometime around 2001. Some of the 2001 models had them, others didn't. I had to get a fuel rail from a 2000 to put on my 2005, just so I could have a Schrader valve.
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Really? Cause I'm pretty sure I have mine on my 02. And the Mopar replacement I bought for it has one.
 
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Philthy said:
Really? Cause I'm pretty sure I have mine on my 02. And the Mopar replacement I bought for it has one.
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There wasn't a concrete year cut off near as I could tell when I was researching this.

I just know that they definitely didn't come on any 03-06 models, and when I started looking into it, it seems they did away with them sometime in 2001, but maybe they put a few leftovers on 2002 models. Either way, it's stupid that they did away with such a helpful thing to have.

The good thing is you can just get a fuel rail from an earlier model and it swaps right on without any issue. That's what I did.
 
Sounds like fuel pressure to me also, but I would t just go and buy a new pump. Figure out how to test the pressure. Pretty sure you can set up and adapter right to the line
 
Ok guys tested the fuel pressure and it sits at 49 psi the whole time revved it up to 2000rpms and still sat at 49. It keeps throwing random p0301 or p0305 it changes every time we clear the code the only persistent code is p0300 at this point were thinking a vaccum leak we checked all the fuel injectors and there working accordingly. How can I check for vaccum leak other then inspecting the hoses for obvious cracks or rips
 
That problem wouldn't make me think vacuum leak. You never verified what Champion plugs the shop installed, pull one and tell us what model it is. The wrong model Champion like their 3034, which incorrectly shows as an ok replacement in the guide, can cause misfires due to your waste-spark ignition system design.
 
This is what the shop said when I called to ask

Screenshot_20190624-121007_Chrome.jpg
 
If it's not all the time same cylinder, I'm betting cap and rotor. The last number is the cylinder. 301 cyl. 1 , 305, cyl 5. It could also be arcing under the cap. Has anyone tried to move the distributor? have you looked for arcing wires at night in the dark?
 
Oldguy said:
If it's not all the time same cylinder, I'm betting cap and rotor. The last number is the cylinder. 301 cyl. 1 , 305, cyl 5. It could also be arcing under the cap. Has anyone tried to move the distributor? have you looked for arcing wires at night in the dark?
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His 2001 won’t have a distributor, later TJ’s have coil packs (direct ignition).
 
Oldguy said:
Did not know that, thanks. Then I would look in the dark with the engine running for wires arcing
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That is actually an excellent way to check for wires arcing, I've used that method lots of times. But it must be dark, and some arcing is so light it takes a few seconds for the eyes to adjust in order to see.
 
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