Questions about P0305 code

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Gatorlaw

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So I previously posted of a check engine light and code. It is P0305 (misfire on cylinder 5). I figure if I swap the plugs I should be good? I look at a video showing what I need to do to get to the plugs and am thinking while there I should just swap the coil packs while I am there. I was also wondering if I should change the fuel injectors as well? 155k miles

Thoughts?

also the misfire is not regular but has happened. Usually in the morning at start up and it runs a bit rough for a couple minutes but cleans up once driving.
 
Hi!!! I'm new to this forum. Received a code P0305. Misfire cylinder 5. My 2014 Wrangler Unlimited has 108,000 miles. Since I had to take the manifold off to deal with cylinder 5 I decided to just go ahead and change out cylinder 4,5,&6 plugs and coils. OEM parts. All went well in the process. After driving it for about 5 miles the engine light came on again with the same code. Is it harmful to the jeep to drive it with this code even though I have those new parts installed? Fuel injector problem? Wiring harness problem? Any advice on what I should do next? HELP PLEASE!!!!! Looking forward to some good advice.
 
Shjohn62 said:
Hi!!! I'm new to this forum. Received a code P0305. Misfire cylinder 5. My 2014 Wrangler Unlimited has 108,000 miles. Since I had to take the manifold off to deal with cylinder 5 I decided to just go ahead and change out cylinder 4,5,&6 plugs and coils. OEM parts. All went well in the process. After driving it for about 5 miles the engine light came on again with the same code. Is it harmful to the jeep to drive it with this code even though I have those new parts installed? Fuel injector problem? Wiring harness problem? Any advice on what I should do next? HELP PLEASE!!!!! Looking forward to some good advice.
Click to expand...
1,3,5 are on passenger side. 2,4,6 are on drivers side. If you took off manifold to change you changed 2,4,6. Your light was likely off due to forced reset via battery disconnect. You can try to change the other side and what happens. When I did that last time I had no engine light for almost 500 miles, but if again returned. At this point I’m done trying to chase down the problem and decided to live with the light till the engine dies. Then will do Hemi swap.
 
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I would try the battery reset if you didn't disconnect the battery cables. It's possible it could be a fuel injector.

With all the work involved in removing the intake manifold you should have went ahead and put new plugs and coils on the other side.
 
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I changed the injectors too and no change. I gave up. I tossed almost 1k chasing the light. Like I said I’m just gonna save the money for a swap.
 
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Wrangler 2014 unlimited JK. Code P0305 misfired cylinder 5. In the process of addressing this problem I've learned a few things. As of now I have replaced all spark plugs and all coils. Also ran a concentrated amount of Sea Foam through the injectors. Thought for a short while I had the problem fixed. Engine light and code zeroed out. One day later it came back. Should I now change the injector on cylinder 5? I pray that it's not an electrical issue. Thoughts? Any help is deeply appreciated.
 
Shjohn62 said:
Wrangler 2014 unlimited JK. Code P0305 misfired cylinder 5. In the process of addressing this problem I've learned a few things. As of now I have replaced all spark plugs and all coils. Also ran a concentrated amount of Sea Foam through the injectors. Thought for a short while I had the problem fixed. Engine light and code zeroed out. One day later it came back. Should I now change the injector on cylinder 5? I pray that it's not an electrical issue. Thoughts? Any help is deeply appreciated.
Click to expand...

It's not an easy answer.

Did you check your VIN to see if the head was part of a recall? They had a bunch of head issues on these stemming from the valve seats overheating and causing misfires.

Could be electrical but all you have there is is the injector and the coil getting it's voltage. The injector could, of course, be going bad or is fouled and not injecting enough or too much fuel.

Do you have something that can see how much it is misfiring and when? Is it a low amount and constant, a high amount only sometimes, etc.

Have you had a compression test performed?

How did the old plugs look? Any signs of carbon tracking?

You could move the coil from #5 to #3 and see if that makes the misfire move to #3.

Basically anything affecting air or fuel delivery, or anything off in the compression, can cause a misfire.
 
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Guys thank so much for taking time to respond. Well, I changed the injector on cylinder 5 and the light still comes on but doesn't show code P0305. I'm confused to say the least. Also, you might find this odd, when i have mt brake fully compressed I can barely feel a vibration in the engine and when I release my brake the hesitation is obvious. What the heck!!!!! Can I have an electrical problem? Will it harm my engine to drive it? While driving, it seems to be running very smoothly.

Didn't know about this recall. How do I check on this? Is there a website?

Thanks guys!!!!
S. Johnson
 
Shjohn62 said:
Guys thank so much for taking time to respond. Well, I changed the injector on cylinder 5 and the light still comes on but doesn't show code P0305. I'm confused to say the least. Also, you might find this odd, when i have mt brake fully compressed I can barely feel a vibration in the engine and when I release my brake the hesitation is obvious. What the heck!!!!! Can I have an electrical problem? Will it harm my engine to drive it? While driving, it seems to be running very smoothly.

Didn't know about this recall. How do I check on this? Is there a website?

Thanks guys!!!!
S. Johnson
Click to expand...

A vibration in the engine can be bad motor/trans mounts, there have been a few of them lately. The vibrations from them can cause problems then with loose/bad connections, grounds especially.
 
Update on my Wrangler problem. I've now changed the plug, coil, fuel injector, and bank 1 O2 sensor with quality parts and I'm still getting a code of P0305. Obvious slight vibration is only felt when I let up on my brake pedal. With the brake full compressed I don't feel it. I've also checked my motor mounts and from what I can see they look good. What's left to check? Computer board or electrical?
Thanks,
S. Johnson
 
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