CEL p0300 misfire

Seahawkfan

Seahawkfan

Hooked
Well, this shit happened today.
Stopped at a light and as I took off Jeep shuttered a little, sounded like shit. Cleared up and ran fine the rest of the way home. Came out next morning, it started but sounded and ran like shit again. P0300 code pops up, 2011 JKU auto trans just turned over 50,000 miles.
After going through all the bullshit exhaust hangers and fittings with the impact gun, No change. I ordered crank shaft sensor. We'll see what happens in the morning.
Where would you start.
Thanks
 
Seahawkfan said:
Well, this shit happened today.
Stopped at a light and as I took off Jeep shuttered a little, sounded like shit. Cleared up and ran fine the rest of the way home. Came out next morning, it started but sounded and ran like shit again. P0300 code pops up, 2011 JKU auto trans just turned over 50,000 miles.
After going through all the bullshit exhaust hangers and fittings with the impact gun, No change. I ordered crank shaft sensor. We'll see what happens in the morning.
Where would you start.
Thanks
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Did you get fuel from a different station than usual recently? I have been seeing some shit fuel with a lot of water in cars at work recently.
 
cozdude said:
Did you get fuel from a different station than usual recently? I have been seeing some shit fuel with a lot of water in cars at work recently.
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Winner winner,, I had just stopped at a Mobil station and pumped about half tank. I have been to the place several times, but always feel a little off.
I pulled over and called the station asked if they had any problems or reports of maybe some bad gas, she said no. Whatcha gonna do?
 
got a bad tank if gas from a station, detached the fuel line from the fuel rail and pumped some fuel into a glass jar.

normally I would've let the jar sit to allow the water and fuel to separate but it was pretty obvious how much water was in the tank and determined my next steps
 
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Seahawkfan said:
Winner winner,, I had just stopped at a Mobil station and pumped about half tank. I have been to the place several times, but always feel a little off.
I pulled over and called the station asked if they had any problems or reports of maybe some bad gas, she said no. Whatcha gonna do?
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Well that sucks. I suggest getting it over to a top tier fuel station and fill the tank with high grade 93. Will dilute the water a bit and help reduce the detonation the water is causing
 
kingsize said:
Pour in a bottle of Iso-HEET and send it.
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Funny that is the first thing I did that and changed back to factory tune from a 91 tune. Not the send it part yet. I
Was just thinking, I have been dealing with a 0442 small evap leak. And lately I have been driving a lot in water and snow. Could it be related? And water is getting in.
 
Anyone knows the best and easiest way to get the fuel out of my tank. or know where the fuel line is under the hood? Is it the one with the blue fastener on it? Anyone know how to disconnect without breaking that fastener?


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better to do this with a cold engine and have a fire extinguisher close by just in case.

put something under the fitting to catch any fuel that will come out, remember it's under pressure.

put a little downward pressure on top of the fitting; not too much, you don't want to break it. While pushing down on the fitting, press in the white part on the side and that will spread the blue clip holding it onto the line.

When you push in the white portion you can feel the fuel line become free, keep pushing on the white tab and gently pull off the line.

it'll be snug but should come off fairly easy.

They make these to hold the clip open easier, slides up from underneath, autopart stores carry them:

Lisle 37000 Air Conditioning/Fuel Line Disconnect Tool Set

it's better to have a second person to turn the key on to activate the fuel pump while you make sure you catch fuel. The fuel comes out pretty fast for about 10 seconds then repeat. do not try to start the Jeep.

have plenty of good size fuel containers to catch the fuel.

did you fill the tank to full? I had 5 gal of good fuel and then drained mine down to less than 1/4, poured in the 5 gal and some heat

I tried siphoning the fuel out by removing the fill hose at the tank, I was able to get a hose past the siphon fuel block but the jeep wasn't high enough in the air to get a good siphon effect going. if you have a lift it would work (y)

fuel line.jpg
 
OverlanderJK said:
remove the blue clip.
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^^^^ This

Remove the blue clip or slide it part way off then press the spot @jeeeep points to. The blue clip is a lock keeping the ears on the white clip from being able to release the line.

I wish I would have known this when I dropped the tank on my JL, I was removing the locks completely then removing the white clip that goes in from the opposite direction. I broke a few and it was a SOB to find replacements, the parts guy at the Jeep dealership could only get me the whole fuel line with the clips already installed.
 
the blue clip can be brittle depending on age.

you can also buy those at autoparts stores, fuel line retaining clips. dorman sells them in multiple sizes but better to be careful and try not to break it
 
jeeeep said:
the blue clip can be brittle depending on age.

you can also buy those at autoparts stores, fuel line retaining clips. dorman sells them in multiple sizes but better to be careful and try not to break it
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I managed to go that route myself at tank. I have one of those extensions on my floor jack. Started with a syphon pump and just pumped it out. It was killing me after only 2 gallons. Got a longer hose and just syphoned the rest. Total about 10 or 11 gallons.
You know anything about bad gas? This is at about 1/4 tank when I pulled it.
20230308_213806.jpg20230308_213916.jpg
 
Seahawkfan said:
I managed to go that route myself at tank. I have one of those extensions on my floor jack. Started with a syphon pump and just pumped it out. It was killing me after only 2 gallons. Got a longer hose and just syphoned the rest. Total about 10 or 11 gallons.
You know anything about bad gas? This is at about 1/4 tank when I pulled it.
View attachment 385824View attachment 385825
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may want to get a larger sample but let it sit for at least an hour, water is heavier and you'll see the separation.

That looks very clear for gas.
 
Seahawkfan said:
Yea that was a quick shot while syphoning. Maybe it wasn't gas alone. This is the first plug I pulled.
View attachment 385866
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damn! you need
c1ec8ae4e4a58fc7fd5939d04bc4a754.jpg


to jump that spark!

I'd change all the plugs.
 
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