1999 Toyota Land Cruiser 4.7 Engine Misfire

I could feel the engine misfire as I drove the vehicle into the shop. There are a lot of ways to test a misfire but usually the best start is to find which cylinder is misfiring and concentrate your efforts there. You can also benefit from having a cylinder with no misfire to compare with the bad one. I started with an ignition scope check at the cylinder #1 coil.

#1 is the front cylinder on the driver's side of the engine. Next back would be #3 and there is where I found a problem.

Verified the misfire was ignition related and was at cylinder #3

I removed the coil and spark plug from #3. The spark plug boot was baked onto the plug and I had to remove a bit at a time to allow the spark plug socket to be used. Not the hardest thing I've ever done but tedious none the less.

I could see the spark plug was completely worn out, the boot was destroyed and the coil was not firing. I needed to verify that a new plug and coil would fix the miss. The easiest way to do that was to install the parts in just that cylinder. Parts installed and misfire gone. The other plugs would need replaced as well and I did have to consider I may have other boots in bad shape.
In the end though new spark plugs, new coil on #3 and the Land Cruiser was ready to cruise some land again.

Kenny@ggauto.repair