View Full Version : Cylinder 1 misfire, plug BLACK
2000 tj sport, which means no spark plug wires, has the "row" they all snap into.
check engine light on, engine missing.
Get a 301 code, cylinder 1 misfire.
Pulled the plug, black as can be (Just changed to Champion Truck plugs about 15k ago). Gap looked fine.
Now obviously I will change the #1 plug, but what would be causing this? Engine running rich? Why?
Did some searching, came up with some hits on people having similar problems, but didnt really identify the "why"
Thanks
I would think that the coil is breaking down. That or the plug is broken. HTH
Pick
Doc Johnson
06-05-2003, 03:12 PM
Since I am not familure with your engine I am guessing it has a coil pack for each cylinder? :confused: If so your coil could have failed or your plug went bad.
THe wire could have come loose to the coil as well.
sothpaw
06-05-2003, 04:49 PM
You should have one coil for each two cylinders, so if the coil is bad, you would have two plugs misfiring. I would replace the plug and see if it reoccurs. Check the plug boot on the rail and make sure it is making good contact with the tip of the spark plug. If it turns out to be the coil rail they are only like 60.00 for a new one. Not too bad, considering it is from the dealer.
Did you check any of the other plugs to see what they looked like? If they are all black you may be running rich for some reason.
other plugs look fine. #3 had a little black in one area, almost a line, but the tip looked fine, and the rest of the body was white. actually the rest look almost too white. I'm going to regap them to .035 and see what happens....and of course replace #1.
Do the coils work as you would think, 1/2 3/4 5/6 or would it be in the firing order? 1/3......because maybe it is the coil then?
The coils are actually split per cylinder, so a coil could be bad on only one cylinder. HTH
Pick
sothpaw
06-05-2003, 11:28 PM
Originally posted by Pick
The coils are actually split per cylinder, so a coil could be bad on only one cylinder. HTH
Pick
Uhh, what do you mean? There are three coils and six cylinders.
The 2002 TJ FSM on page 8i-10 states: "Although the firing order is the same as 4.0L Jeep engines of previous years, spark plug firing is not. The 3 coils dual fire the sprak plugs on cylinders 1-6, 2-5, and/or 3-4. When one cylinder is being fired (on compression stroke), the spark to the opposite cylinder is being wasted (on exhaust stroke)."
Gotta stop the disinformation from spreading!:flipoff2:
CP8071
06-06-2003, 09:44 AM
Kinda suprised nobody has suggested a compression check or that the injector could be bad. Could be something more serious than ignition problems.
CP
Originally posted by sothpaw
Uhh, what do you mean? There are three coils and six cylinders.
The 2002 TJ FSM on page 8i-10 states: "Although the firing order is the same as 4.0L Jeep engines of previous years, spark plug firing is not. The 3 coils dual fire the sprak plugs on cylinders 1-6, 2-5, and/or 3-4. When one cylinder is being fired (on compression stroke), the spark to the opposite cylinder is being wasted (on exhaust stroke)."
Gotta stop the disinformation from spreading!:flipoff2:
My Bad! You are correct, I appologize.
Pick
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