I made a discovery on how to fix misfires on my 2003 H2 that I bought new in 2003. It now has 198,000 miles. Last year it developed a persistant misfire at low RPMs. I checked the spark plug wires and could see one was not sparking consistantly. I bought a set or coils and sparkplugs and replaced that one coil. I looked at the spark plug and it had a tiny tip... my first time seeing that kind of plug. But the plug looked totally OK. The replacement plugs I bought were the normal kind with a fat electrode. I put the original plug back in. Yes, 198,000 miles on the spark plugs. It ran fine for a year then the misfire started again. It was hard to identify the bad coil this time. The little spark indicator I was using showed rare misfires on all the coils. I decided to clean the connectors where the wire plugged into the coil and into the spark plug. I sprayed each end with contact cleaner and then WD-40. Plugged that wire back in, then the next one. They connectors had a layer of whitish stuff inside and were very hard to pull apart... very high friction. Well, all the misfires are gone... been two weeks now. So the coils were not defective and the spark plugs were not failing. Poor connections cause a LOT of problems.

 

Thanks for the fix info. From now on, can you please ALL H2 content in the H2 Section. The new member area is strictly for intros by new members, not tech questions/info.