The dreaded "Random Misfire"
Thread Starter
Instructor
Joined: Oct 2006
Posts: 123
Likes: 1
From: Yelm Washington
The dreaded "Random Misfire"
I need some more brains to ponder my current problem. Today while driving the car I got the "service soon" light; upon returning home I recovere the code which was/is "Random Misfire" which I know from my last adventure is very generic. Just to bring any reader to speed I recently (less than 300 miles ago) installed the following;
New Optic Spark w/cap
New MSD coil
New water pump
New MSD 8.8 wires
New fuel pump
Soon after this above install I felt the car missing slightly and upon reaching home discovered that the left rear spark plug wire was arching to the exhaust manifold. I installed a "boot" (the thermal kind to keep the wires from burning on headers) which seemed to help. I only installed the boots on the left back 2. Since then I have not noticed any more arching but now I am wondering. My thoughts are either that more wires are now arching (which I am about the check) and/or because I stuffed the wires in the stock looms that they are or have somehow began cross arching (wire to wire). I am going to go and try and free up the wires and possibly install more boots/covers to see if this helps but I am opening wondering if there could be something more problematic looming.
I'd love to hear more thoughts on this.
New Optic Spark w/cap
New MSD coil
New water pump
New MSD 8.8 wires
New fuel pump
Soon after this above install I felt the car missing slightly and upon reaching home discovered that the left rear spark plug wire was arching to the exhaust manifold. I installed a "boot" (the thermal kind to keep the wires from burning on headers) which seemed to help. I only installed the boots on the left back 2. Since then I have not noticed any more arching but now I am wondering. My thoughts are either that more wires are now arching (which I am about the check) and/or because I stuffed the wires in the stock looms that they are or have somehow began cross arching (wire to wire). I am going to go and try and free up the wires and possibly install more boots/covers to see if this helps but I am opening wondering if there could be something more problematic looming.
I'd love to hear more thoughts on this.
Le Mans Master
Joined: Mar 2004
Posts: 8,700
Likes: 298
From: Ft. Lauderdale Fl
If all else fails, try this test. At night, in a dark garage, pop the hood and start the engine. Look for a spark gap near your plug wires. They touch and ground out and you have a random misfire.
With a zip tie, reposition the plug wire and your good to go.
With a zip tie, reposition the plug wire and your good to go.
Burning Brakes
Joined: Aug 2007
Posts: 769
Likes: 0
From: Cincinnati OH
Two things I see. First, it looks like you replaced everything but the plugs. Unless I missed that in your post.
Second, the arc may still happen through the boot that you have over the plug wire.
Mike
Second, the arc may still happen through the boot that you have over the plug wire.
Mike
Thread Starter
Instructor
Joined: Oct 2006
Posts: 123
Likes: 1
From: Yelm Washington
I did replace the plugs with new platinums.
I moved the wires around and drove the car today without incident so I am not sure if I fixed it or not.
For those in Western Washington I am told there is a Vette meet in Olympia tomorrow.
I moved the wires around and drove the car today without incident so I am not sure if I fixed it or not.
For those in Western Washington I am told there is a Vette meet in Olympia tomorrow.
