Novak Conversions Jeep Wrangler TJ radiator

Difficult P0300 Misfiring Issue

Heavyp08

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Joined
Feb 20, 2021
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12
Location
SoCal
Hey gang, I'm at my wits end, mostly cuz I'm scared of what's happening to my dream Wrangler. Sorry if this post seems long but I want to provide as much details as possible so hopefully someone can point me in the right direction. So here is a little backstory and info:

About 5 months ago, I privately bought a 2005 Wrangler TJ Unlimited Rubicon with 120k miles. Paid a pretty penny for it to be honest. I pulled the trigger because at first impression, its BEAUTIFUL and the color I love most. The car is in fantastic shape, extremely little rust, relatively low miles, and after test driving it for about 30 mins - it pulled very nicely. Everything worked and I was sold on it. I was on cloud 9 for a time: "I finally own my very own LJR!" -Me

Starting a few weeks ago, my heart sank. Out of no where, on the highway while I was giving it gas, I felt VERY little power as I stepped on the throttle. I looked down and bam - flashing/blinking check engine light. I got so scared, I went straight back home as I was only about 5 miles away. It blinked the majority of the time home, but I trucked through and drove it incredibly slowly. I got home and immediately started doing my HW on this and it looks like I am misfiring. I am not well versed in this so I immediately made an appointment with my local (well reviewed on Google) mechanic shop and took it in. Paid for the ultra premium inspection. 2 days and $200 later, they call me "dude. thing is immaculate. Our mechanics couldn't replicate the flashing check engine light, there are NO stored codes, and it drove straight as an arrow. Im sorry but if we don't find anything during test drive and no codes being stored - this car is fine." ugh.

I picked it up and drove it home. He was right, no lights and no flashes. I drove it another 4 days without anything popping up again and on that 5th day, it happened again: little to NO power and the check engine was flashing.

I took it to another mechanic for another opinion. Paid $180 for their inspection and that same day, I decided to call the person who sold it to me. This was an elderly gentleman and I was straight up with him: "Hey dude, I know you already sold me the car and I do still love it but would you mind being as honest as possible for a sec? The car seems to be misfiring. Did you have anything like this when you owned it? Please be honest with me, I will not get mad, I still want to own the car, and I just want to get whatever is wrong fixed."

He replied with, "I owned that car for years and never had an issue anything like what you are describing. I am sorry. If you would like, I work with a mechanic here by my home and would happily pay for an inspection." I told him I would look into that.

A few hours later, the 2nd mechanic called me: "Bro there's nothing wrong with this Jeep. Come take it home."

(note: I 100000% believe the previous owner when he said he didn't have any issues with the wrangler, I have all his contact info, met him at his home, and I'll be honest: this is a man of means and wealth. His community is gated and he has lots of toys.)

So here I am: dream wrangler in my garage but its misfiring. I don't want to drive it because I am scared I am doing intense damage to it.

Things that were done to it after the original check light flashing:
  1. new top of the line iridium spark plugs were installed and torqued to spec. Before you say anything, these plugs were recommended by the Jeep dealer and mechanics. It originally had Champion Copper plugs and with those installed, it still flashed the light.
  2. Brand new BlueStreak ignition coils were installed. Mopar doesn't make NEW coils for this and I refused to use the ultra cheap AutoZone parts. So im using this bluestreak.

Sorry for the long post but I hope there's someone out there who might be able to help. If it matters, I'm in Colorado.

Pics of Wrangler and quick video of flashing:

https://drive.google.com/drive/folders/1osp7tYEQp9umkfFxaPHhCnX9y1Qqq2FO?usp=sharing


pls help :(
 
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Reactions: Wranglerfix
Hey gang, I'm at my wits end, mostly cuz I'm scared of what's happening to my dream Wrangler. Sorry if this post seems long but I want to provide as much details as possible so hopefully someone can point me in the right direction. So here is a little backstory and info:

About 5 months ago, I privately bought a 2005 Wrangler TJ Unlimited Rubicon with 120k miles. Paid a pretty penny for it to be honest. I pulled the trigger because at first impression, its BEAUTIFUL and the color I love most. The car is in fantastic shape, extremely little rust, relatively low miles, and after test driving it for about 30 mins - it pulled very nicely. Everything worked and I was sold on it. I was on cloud 9 for a time: "I finally own my very own LJR!" -Me

Starting a few weeks ago, my heart sank. Out of no where, on the highway while I was giving it gas, I felt VERY little power as I stepped on the throttle. I looked down and bam - flashing/blinking check engine light. I got so scared, I went straight back home as I was only about 5 miles away. It blinked the majority of the time home, but I trucked through and drove it incredibly slowly. I got home and immediately started doing my HW on this and it looks like I am misfiring. I am not well versed in this so I immediately made an appointment with my local (well reviewed on Google) mechanic shop and took it in. Paid for the ultra premium inspection. 2 days and $200 later, they call me "dude. thing is immaculate. Our mechanics couldn't replicate the flashing check engine light, there are NO stored codes, and it drove straight as an arrow. Im sorry but if we don't find anything during test drive and no codes being stored - this car is fine." ugh.

I picked it up and drove it home. He was right, no lights and no flashes. I drove it another 4 days without anything popping up again and on that 5th day, it happened again: little to NO power and the check engine was flashing.

I took it to another mechanic for another opinion. Paid $180 for their inspection and that same day, I decided to call the person who sold it to me. This was an elderly gentleman and I was straight up with him: "Hey dude, I know you already sold me the car and I do still love it but would you mind being as honest as possible for a sec? The car seems to be misfiring. Did you have anything like this when you owned it? Please be honest with me, I will not get mad, I still want to own the car, and I just want to get whatever is wrong fixed."

He replied with, "I owned that car for years and never had an issue anything like what you are describing. I am sorry. If you would like, I work with a mechanic here by my home and would happily pay for an inspection." I told him I would look into that.

A few hours later, the 2nd mechanic called me: "Bro there's nothing wrong with this Jeep. Come take it home."

(note: I 100000% believe the previous owner when he said he didn't have any issues with the wrangler, I have all his contact info, met him at his home, and I'll be honest: this is a man of means and wealth. His community is gated and he has lots of toys.)

So here I am: dream wrangler in my garage but its misfiring. I don't want to drive it because I am scared I am doing intense damage to it.

Things that were done to it after the original check light flashing:
  1. new top of the line iridium spark plugs were installed and torqued to spec. Before you say anything, these plugs were recommended by the Jeep dealer and mechanics. It originally had Champion Copper plugs and with those installed, it still flashed the light.
  2. Brand new BlueStreak ignition coils were installed. Mopar doesn't make NEW coils for this and I refused to use the ultra cheap AutoZone parts. So im using this bluestreak.

Sorry for the long post but I hope there's someone out there who might be able to help. If it matters, I'm in Colorado.

Pics of Wrangler and quick video of flashing:

https://drive.google.com/drive/folders/1osp7tYEQp9umkfFxaPHhCnX9y1Qqq2FO?usp=sharing


pls help :(

2004 tj unlimited was getting various misfires p300 was the most common. P303 04 and 06 would come and go as well. Replaced plugs all was good for a few months then started back - replaced crank positioning sensor again all cleared for a bit then got 300 304 and 306...they would clear on their own then come back. Usually would get them if driving in stop and go traffic or short stops at store gas station etc. Solution: heat shield was almost none existant and no heat wrap on fuel rail. I pulled fuel rail cleaned injectors and put new heat shield and fuel rail wrap on..30 bucks on amazon. All clear running smooth..easy to do took about 2 hours.
 
2004 tj unlimited was getting various misfires p300 was the most common. P303 04 and 06 would come and go as well. Replaced plugs all was good for a few months then started back - replaced crank positioning sensor again all cleared for a bit then got 300 304 and 306...they would clear on their own then come back. Usually would get them if driving in stop and go traffic or short stops at store gas station etc. Solution: heat shield was almost none existant and no heat wrap on fuel rail. I pulled fuel rail cleaned injectors and put new heat shield and fuel rail wrap on..30 bucks on amazon. All clear running smooth..easy to do took about 2 hours.

My 06 lj had simmilar issue as yours. It was the fuel pump. But id inspect your exhaust manifold heat shield and fuel rail wrap - heat off manifold causes fuel to vaporize in rail. Plugs, double platinums autolite XP895. If both ok cam and crank positioning sensor and check fuel pressure for possible fuel pump failing.
 
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Couldn’t agree more with what’s being said.

Fuel pressure: not just prime pressure and running pressure. Ideally, only test when it’s acting up and warmed up (seems to be a common theme). Throttle snaps and brake torque while observing fuel pressure.

Heat soak (wrap #3 & 4) injector at minimum and make sure your heat shield is in good condition. (See picks below)

Crank/cam position: possibly, tackle the top two first.

IMG_3792.jpeg


IMG_3793.jpeg
 
I'd argue that it depends on where you live. Texas hill country 110 days and an engine that runs at 210...fuel tends to vaporize in the rail and that messes with the injectors. For 28.00 and knowing you cleaned the injectors . Wrap it you're there anyway.
 
Novak Conversions Jeep Wrangler TJ radiator