I can't remember changing the spark plugs in my Jeep, so I decided to knock it out today. The old plugs that came out looked terrible. They are NGK plugs, and I wonder if they are the factory plugs (2005 4.0 with 172k Miles on the odometer).
New plugs:
AutoLite Double Platinum Spark Plug: Part No. APP985
Things went well as far as I knew. I used a bit of dielectric grease, applied to the ceramic tip on each plug, and a wisp of antisieze on the threads. Gapped each plug to 0.035 and torqued down to 26 ft lbs.
Upon startup, I was greeting by a flashing check engine light - scanner said it was a cylinder 4 misfire.
I pulled the coil rail off, looked everything over, put the coil rail back on, and started it up. The idle stumbled quite a bit, check engine light came on, and the scanner proclaimed "multiple cylinder misfires".
Could this just be that I botched when applying dielectric grease, and pulling, then putting back on the coil rail smeared the grease causing the spark to fail? The grease was applied directly to the ceramic portion of the spark plug before going into the engine.
I know these plugs have a crush washer - can I remove plugs, inspect, and reuse them, or will I need a new plug (with a fresh washer)?
Here are the old plugs, with a new (properly gapped) one in the center. Some of the old plugs have a gap of 0.085!
New plugs:
AutoLite Double Platinum Spark Plug: Part No. APP985
Things went well as far as I knew. I used a bit of dielectric grease, applied to the ceramic tip on each plug, and a wisp of antisieze on the threads. Gapped each plug to 0.035 and torqued down to 26 ft lbs.
Upon startup, I was greeting by a flashing check engine light - scanner said it was a cylinder 4 misfire.
I pulled the coil rail off, looked everything over, put the coil rail back on, and started it up. The idle stumbled quite a bit, check engine light came on, and the scanner proclaimed "multiple cylinder misfires".
Could this just be that I botched when applying dielectric grease, and pulling, then putting back on the coil rail smeared the grease causing the spark to fail? The grease was applied directly to the ceramic portion of the spark plug before going into the engine.
I know these plugs have a crush washer - can I remove plugs, inspect, and reuse them, or will I need a new plug (with a fresh washer)?
Here are the old plugs, with a new (properly gapped) one in the center. Some of the old plugs have a gap of 0.085!
Last edited: