Spark Plug Boots Blister

Question:

what would cause the spark plug boots to blister on 2 plugs at the tip of the plug . 3 sets new wires . 135000 miles 2002 Chevy express 3500 5.7

Answer:

Maybe the spark plugs themselves, have you moved those plugs to a different location or just replaced them ........ How about the obvious, leaking exhaust manifold gasket ? or cracked manifold leaking exhaust gases out onto the plug boots!!!

You may not hear the exhaust leak like normal , it may just sound like a miss, you may be at the beginning stages, look for blackish carbon around the manifold where the two plug boot keep getting effected. The spark plugs may be cracked and arching. Wrap electrical tape around the boots. That might be the cause of the miss. Also if there is an exhaust leak, the o2 sensor will try to compensate and may cause it to run different then normal.