Mechanics

MITSUBISHI ECLIPSE SPARK PROBLEM

2000 Mitsubishi Eclipse • 167,000 miles

While driving home from work yesterday on the highway, my eclipse started to misfire terribly. I was able to make it to the parts store. I replaced both coil packs and it started to smooth out some but still was missing. So I started pulling the spark plugs thinking that I may have fouled a plug while driving with a bad coil pack. Upon removing the plugs I found that the plug in the #2 cylinder had a bent elctrode and the plug in the #4 cylinder had the elctrode broken completely off. It was almost like the piston had came up and smacked the spark plug. There is no knock or lower engine noise of any kind. I tried running a magnet in the #4 cyclinder to get the broken elctrode out, with no luck. I also turned the car over while the plug was out, trying to blow out the elctrode, again with no luck. I replaced both spark plugs and the car seemingly was fixed. There was no miss and no noise, almost running perfect. So on my way to work today, I decided to make sure in was fixed. While driving down the road at 30mph, I punched the gas. The car down shifted. It got up to around 4500rpm and started missing again. I started pulling the plugs and found that this time it had a bent elctrode in cylinder #3. I re-gapped the spark plug and put it back in. The car runs fine as long as I baby it and dont cause it to go over 4000rpms. I also ran a compression check on all 4 cylinders and they all were around 160-175psi which seems to be good. Does anyone know what could cause this?
Avatar
Scottiec
October 17, 2012.



Usually either the wrong spark plugs or the bearing journals are getting worn and letting the pistons travel too far up and contact the spark plugs.

Promechanic
Oct 17, 2012.