Mar 3, 2015, 12:30 PM
Last edit by: IB Advertising
See related guides and technical advice from our community experts:
Browse all: Engine and Powertrain
- Why is my cat misfiring?
Guide to diagnose trouble with recommended solutions.
Browse all: Engine and Powertrain
P0300: Misfire from hell
Le Mans Master
Joined: Jul 2010
Posts: 6,013
Likes: 726
Couple days ago my C5 after I got on it, backed off quickly started to run rough, idle rough, backfire but got her home. Now after researching the P0305 code I am in the process of removing the ignition coil, ok, no problem so far, then pulled wire off coil to spark plug, tried to remove wire from spark plug and yes I broke it, ok, will buy another, the problem is I can not get the wire off of the spark plug (very tight for hands to operate) or able to remove the metal can cover protecting the spark plug. I would appreciate any help/advice on how to remove the plug and wire, from cylinder #5? Thank you, a new member.
P..s I don't know if your comfortable enough but i've done this. Break the head of the spark plug off. If you can't get it. the other ways
Last edited by helga203; May 1, 2021 at 04:04 PM.
Cruising
Joined: May 2021
Posts: 14
Likes: 0
helga203, thank you for the reply, the broken wire is still connected to the plug, the metal can protector is also still on, I can't get pliers in there with enough bite to pull either one off. Do they require any special procedure to remove or just grab hold and pull as hard as I can? Not much room to get a tool in there and pull on them. Any tips on pulling them out. Thanks.
Thread Starter
Racer
Joined: Aug 2000
Posts: 460
Likes: 12
From: Gulf Shores AL
Just pull hard, it will come off. If the metal insulator is on, a needle nose on each side should bring the insulator, rubber boot, and connector all together. If the insulator is off, just grab the rubber boot and pull hard. Worst case, you might crack the porcelain on the plug, which you can replace.
Le Mans Master
Joined: Jul 2010
Posts: 6,013
Likes: 726
helga203, thank you for the reply, the broken wire is still connected to the plug, the metal can protector is also still on, I can't get pliers in there with enough bite to pull either one off. Do they require any special procedure to remove or just grab hold and pull as hard as I can? Not much room to get a tool in there and pull on them. Any tips on pulling them out. Thanks.
\
Many people including me broke the head of the plug. We get lazy and don't take the plug out when we have to remove a header.
Last edited by helga203; May 1, 2021 at 05:37 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Jul 2010
Posts: 6,013
Likes: 726
Let as know how it goes
Race Director
Joined: Oct 2004
Posts: 12,864
Likes: 4,667
Pro
Joined: Oct 2020
Posts: 529
Likes: 197
From: Columbus, MS
Couple days ago my C5 after I got on it, backed off quickly started to run rough, idle rough, backfire but got her home. Now after researching the P0305 code I am in the process of removing the ignition coil, ok, no problem so far, then pulled wire off coil to spark plug, tried to remove wire from spark plug and yes I broke it, ok, will buy another, the problem is I can not get the wire off of the spark plug (very tight for hands to operate) or able to remove the metal can cover protecting the spark plug. I would appreciate any help/advice on how to remove the plug and wire, from cylinder #5? Thank you, a new member.
If all that checks good it's time for a compression and leak down test. Also not a bad idea to boroscope the cylinder to look for issues on the piston.
Good luck!
Le Mans Master
Joined: Jul 2010
Posts: 6,013
Likes: 726
Cruising
Joined: May 2021
Posts: 14
Likes: 0
P0300: Misfire from hell - Resolved!!
Hey Guys, thanks to all for the input/help. I finally got the plug wire, metal heat shield and plug removed from cycl #5, using a lot more muscle and pulling hard, it finally gave way. Did not have to use the hammer, so plug was not destroyed just the plug wire was broken. When I removed the plug I examined it and saw it had a deep crack down the ceramic, replaced the original ignition coil, new plug wire and new plug, cranked her up and ran smooth as a kittens purr, road test went well. Now just have to replace the other seven plugs and wires. Should be easier now, I have a handy dandy plug removing tool to make pulling the plug wire off. Thanks again to all who replied. Note: The code I was getting was P0305 not P0300.
Last edited by C5art; May 6, 2021 at 03:22 PM.
Pro
Joined: Oct 2020
Posts: 529
Likes: 197
From: Columbus, MS
Hey Guys, thanks to all for the input/help. I finally got the plug wire, metal heat shield and plug removed from cycl #5, using a lot more muscle and pulling hard, it finally gave way. Did not have to use the hammer, so plug was not destroyed just the plug wire was broken. When I removed the plug I examined it and saw it had a deep crack down the ceramic, replaced the original ignition coil, new plug wire and new plug, cranked her up and ran smooth as a kittens purr, road test went well. Now just have to replace the other seven plugs and wires. Should be easier now, I have a handy dandy plug removing tool to make pulling the plug wire off. Thanks again to all who replied. Note: The code I was getting was P0305 not P0300.
Thread Starter
Racer
Joined: Aug 2000
Posts: 460
Likes: 12
From: Gulf Shores AL
Hey Guys, thanks to all for the input/help. I finally got the plug wire, metal heat shield and plug removed from cycl #5, using a lot more muscle and pulling hard, it finally gave way. Did not have to use the hammer, so plug was not destroyed just the plug wire was broken. When I removed the plug I examined it and saw it had a deep crack down the ceramic, replaced the original ignition coil, new plug wire and new plug, cranked her up and ran smooth as a kittens purr, road test went well. Now just have to replace the other seven plugs and wires. Should be easier now, I have a handy dandy plug removing tool to make pulling the plug wire off. Thanks again to all who replied. Note: The code I was getting was P0305 not P0300.
great news...the misfire is a common problem and usually a lot harder to solve. congratulations!