P0304

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ace95621

New member
So on Sunday I drove into town for lunch and started up fine and was running ok beside some shifting issues, I parked then when I got done having lunch I tried remote starting my car they lights blinked so when I got in the car and started it the traction light came on the car started shuttering and shaking badly so took it down to get the code read and came up with p0304 thinking it might be the fuel injector so I switched it out and still is mis firing alot have new spark plugs which are only a couple of months old. Any help would be great appreciated

I have a 2013 1.8 hb sonic
86446k miles

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JesusTheAgnostic

JesusTheAgnostic

New member
It might be the new spark plugs. Any particular reason why you changed them out? I think they're good for 100k miles. What kind of plugs did you use? I know I had some misfires when I changed my plugs from coppers to platinums in my Mustang. I changed them to coppers later on and changed all the wires and that solved my issue. They told me to change my injectors at AutoZone but those things are like $60 a piece. I decided not to I just ran some of that fancy pants tune up in a bottle from Lucas. It's called Lucas Upper Cylinder Lubricant and Injector Cleaner. I'd say try Pulling the plugs from all the cylinders and compare them. See that they're visually fine also that they are the right spacing or whatever it's called. If that doesn't work try the Lucas thing or whatever kind of fuel system cleaner you prefer. I'd like to point out though that my car is the Turbo one and in the manual it says that I should use top tier fuel, because it has more cleaning agents in it to clean the engine. Not sure if it applies to the 1.8 but it might. It says that if you don't use top tier fuel to use GM's fuel system cleaner with every oil change.

Keep in mind though that I'm not a mechanic just an amateur car enthusiast.
 
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ace95621

New member
Yeah changed out the stock what I'm guessing what was stock spark plugs with ngk xp plugs they might be gapped at .58

Last ran though some fuel injector cleaner like a day or 2 before this happened I just thought about it

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zippypcs

zippypcs

Site Supporter
Pull the coil pack off. Look up in each of the boots. Green condensation/oxidation is a likely culprit.
Mine had to be replaced at around 55k I think due to this.
You will prolly find that the boot towards the driver side is the culprit.
As far as I know there is not a replacement for just the boots .
I ordered a complete GM coil pack from Amazon for under 80 bucks.
 
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ace95621

New member
When I tried switching out one of the spark plugs the #4 boot is still grey but 1 and 2 have that brown ish color I can't differentiate the color very well

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ace95621

New member
Another thing that was thinking maybe it is the fuel filter but did some digging on here and it doesn't have a dedicated fuel filter

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zippypcs

zippypcs

Site Supporter
Pull the coil boot off from the coil and check the end at the coil pack. Mine didn't show any problem until I pulled the end one apart and saw all of the oxidation. This was causing a P0304. Code means mis fire cylinder # 4.
 
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ace95621

New member
The rubber end pieces are grey with no discoloration, thought you ment the top rubber boots

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ace95621

New member
I'm really new at this kind of engine set up, I had a 04 caravan and a 91 explorer before that where I could do the work my self and everything was pretty much straight forward so I've been sitting here at the dealership waiting to hear what they have found that I have missed, hopefully it's covered under the powertrain warranty as my extended warranty was up 10k miles ago

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zippypcs

zippypcs

Site Supporter
The warranty for extended most likely will only cover major components. Please let us know what they come up with as I am curious as to what they have to say.
I am guessing coil pack but we will see.
 
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ace95621

New member
Just talked to them before going for a walk coil pack is bad on the #1 and 2 so they are replacing it quoting around 150 and hour hour and half labor to replace it which sounds really high time wise

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ace95621

New member
Yeah takes no time to replace so I take it the coil pack doesn't fall under powertrain?

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zippypcs

zippypcs

Site Supporter
power-train warranty (5year/100000 mile) the injectors, coil packs, and other sensors are not covered! Mainly just mechanical items.
 
Chevrolet Customer Care

Chevrolet Customer Care

New member
ace95621 said:
So on Sunday I drove into town for lunch and started up fine and was running ok beside some shifting issues, I parked then when I got done having lunch I tried remote starting my car they lights blinked so when I got in the car and started it the traction light came on the car started shuttering and shaking badly so took it down to get the code read and came up with p0304 thinking it might be the fuel injector so I switched it out and still is mis firing alot have new spark plugs which are only a couple of months old. Any help would be great appreciated

I have a 2013 1.8 hb sonic
86446k miles

Sent from my SAMSUNG-SM-G870A using Tapatalk
Click to expand...

Good afternoon ace95621,

Sorry to hear that you're experiencing this misfire concern with your Sonic. Have you brought this to the attention of your dealership yet? If you're interested in taking it in for a diagnosis, please let me know and I'd be happy to assist.

Chelsea D.
Chevrolet Customer Care
 
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