Engine misfire
Thread Starter
Le Mans Master
Joined: Aug 2005
Posts: 7,201
Likes: 0
From: DP(oh you know where) IL
St. Jude Donor '06
Engine misfire
Here is my code
P0300 Engine Misfire Detected
I just installed dynatech headers system. I also installed new ngk 55ix spark plugs when i did the header install.
How do I fix this? thanks
Dave
P0300 Engine Misfire Detected
I just installed dynatech headers system. I also installed new ngk 55ix spark plugs when i did the header install.
How do I fix this? thanks
Dave
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Your car is helplessly broken so I will take it off your hands for $500. 
You most likely damaged a sparkplug wire or broke/cracked a sparkplug insulator. The P0300 code will clear it self once the issue is fixed.
Make sure you only pull off the wires using the boots. Dont pull on the wires!
Use an ohm meter and check each wire end to end. You should see 250-750 ohms. The boots and wire jackets should be free of nicks, cuts, tears and burns. Use silicone grease on the boot ends so that they slip on and off easy and seal against moisture. There are other things that can cause the misfire but lets try this stuff first.
When my headers were installed, i found a cracked insulator!
bill
You most likely damaged a sparkplug wire or broke/cracked a sparkplug insulator. The P0300 code will clear it self once the issue is fixed.
Make sure you only pull off the wires using the boots. Dont pull on the wires!
Use an ohm meter and check each wire end to end. You should see 250-750 ohms. The boots and wire jackets should be free of nicks, cuts, tears and burns. Use silicone grease on the boot ends so that they slip on and off easy and seal against moisture. There are other things that can cause the misfire but lets try this stuff first.
When my headers were installed, i found a cracked insulator!
bill
Thread Starter
Le Mans Master
Joined: Aug 2005
Posts: 7,201
Likes: 0
From: DP(oh you know where) IL
St. Jude Donor '06
Thanks, I installed new wires b/c the old ones needed an attitude adjustment, so i got new ones. But i will still check it out. won't hurt. Guess I should buy some insulating stuff for the wires too huh?
Burning Brakes
Joined: Aug 2000
Posts: 889
Likes: 0
From: DFW tx
Without the heat shields, it is only a matter of time before the heat from your headers destroys your wires -- especially if any of the wires are touching the headers. My MSD wires lasted about 30 minutes after I did heads/cam. The extra heat dry rotted out the boots. Went back to stock wires with heat shields and have been fine since.
Thread Starter
Le Mans Master
Joined: Aug 2005
Posts: 7,201
Likes: 0
From: DP(oh you know where) IL
St. Jude Donor '06
Yea, I reinstalled the metal covers that go over the boots. I'm wondering now that after i torqued things down, if i moved a wire onto the header. Also, I know this is dumb, but how bad is it to drive the car when its misfiring?
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Driving the car a short distance should not hurt it but you are dumping RAW fuel into the CATS and this WILL cause them to over heat and melt inside. Let the car rest until you fix the issue.
Yes, it is possible to completly foul a plug with grease.
BC
Yes, it is possible to completly foul a plug with grease.
BC
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Thread Starter
Le Mans Master
Joined: Aug 2005
Posts: 7,201
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From: DP(oh you know where) IL
St. Jude Donor '06
oh you guys are gonna get a good laugh at this one. When i was reinstalling my dipstick, I pulled the wire off the spark plug and forgot to reinstall the wire. oooops!!! Thanks for the help guys. DUH to me. At least it was an easy fix.
Le Mans Master
Joined: Nov 2002
Posts: 7,179
Likes: 2
From: Charlotte, NC
Originally Posted by DPG
oh you guys are gonna get a good laugh at this one. When i was reinstalling my dipstick, I pulled the wire off the spark plug and forgot to reinstall the wire. oooops!!! Thanks for the help guys. DUH to me. At least it was an easy fix.
It happens.... not to me but it happens.. just kidding.. glad it was something simple... -=Rick
Thread Starter
Le Mans Master
Joined: Aug 2005
Posts: 7,201
Likes: 0
From: DP(oh you know where) IL
St. Jude Donor '06
Thanks guys, thanks. I guess I was just to excited to double check things. Live and learn. But I do have to thank you guys for your help, Thanks
Dave
Dave