Jeep Wrangler Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
340 Posts
Discussion Starter #1
After wheeling one night my check engine light was on it was a misfire on cyl 1 so i did a tune up but the plugs where pretty new like 4 months old so i pulled cly one plug it looked like it was firing out the side not the top. It was pretty burnt so i put a new plug in now after a day or so same code again for cyl 1 any ideas?
 

·
Knows a couple things...
Joined
·
49,003 Posts
Might have gotten some moisture underneath the distributor cap. I'd remove the cap and rotor and dry things out and see if that works. If your cap is old, it may not fit as tight as needed to keep water splashes out. I'd replace it and the rotor with a new one with brass contacts, those with aluminum contacts don't last as long.

Or it could be from old cracked ignition wiring letting moisture short the spark out to the block. If it's old, replace it with the factory OE wiring which is much better quality and longer lasting than pretty much most of the aftermarket junk sold in stores like AutoZone. Do resist the temptation to go with any of the much hyped "Low Resistance" spark plug wiring. While low resistance sounds good to the layman, it's not actually a good thing to have where ignition wiring is concerned. It actually costs more to produce the higher resistance wiring which is needed to prevent spark static from interfering with the engine computer, am/fm radio, or CB radio. Not to mention that even though this sounds counter intuitive, lower resistance ignition wiring would not improve engine performance. There's a reason involving a math formula why that I won't get into here. :)
 

·
Registered
Joined
·
340 Posts
Discussion Starter #3
Might have gotten some moisture underneath the distributor cap. I'd remove the cap and rotor and dry things out and see if that works. If your cap is old, it may not fit as tight as needed to keep water splashes out. I'd replace it and the rotor with a new one with brass contacts, those with aluminum contacts don't last as long. Or it could be from old cracked ignition wiring letting moisture short the spark out to the block. If it's old, replace it with the factory OE wiring which is much better quality and longer lasting than pretty much most of the aftermarket junk sold in stores like AutoZone. Do resist the temptation to go with any of the much hyped "Low Resistance" spark plug wiring. While low resistance sounds good to the layman, it's not actually a good thing to have where ignition wiring is concerned. It actually costs more to produce the higher resistance wiring which is needed to prevent spark static from interfering with the engine computer, am/fm radio, or CB radio. Not to mention that even though this sounds counter intuitive, lower resistance ignition wiring would not improve engine performance. There's a reason involving a math formula why that I won't get into here. :)


I have a new cap on and rotor its still doing it there was no water in there but ill take a look at the wiring im sure its old
 

·
Registered
Joined
·
51 Posts
JK misfire

Everything was running good but I decided to change plugs and wires anyway cause it was coming due soon.
So I got 8mm Taylor wires and NGK plugs, put them in and got the dreaded P0300 code, random misfire. I pulled the plugs back out and checked resistance on both plugs and wires, all checks good. I wrapped extra split loom over the wires as they run behind the valve cover to prevent any inductive pickup. Surprisingly, the old plugs had a 0.060" gap.
My question: can lowering the resistance of the circuit cause the computer to bring up the code?
Any thoughts are appreciated, thanks!
 
1 - 6 of 6 Posts
Top