old spark plugs
 

i was wondering i havent replaced my spark plugs in along long time could that be the reson why my car is breaking up alittle on top end? and is causing my car to appear to run rich? im assuming it may not be burning all the fuel? has anyone ever heard of anything like that happening?

Plugs are certainly the first place to look when having those issues. You might as well just replace them (since they are cheap) and see if that solves your problems.

When you say run rich, plug misfire does not cause richness. When a plug does not fire, the fuel does not burn in the engine but in the exhaust system. But there it usually does not burn completely which makes the exhaust seem rich. But actually a WB will show leanness do to less oxygen being consumed which makes it detect more oxygen.

Just today a few of us were screwing around with a work van at my job. A ford windstar with over 178k. Hasnt had a tune up since before 80k! Needless to say it is neglected. It had horrible starting issues and would misfire a shit load. The owner finally wanted us to work on it. We changed the plugs and it started/ran much smoother with no misfire. I wish i could show you a picture of the OLD plugs.

Moral of the story, keep up on maintenance!

Worked on a friends parents truck a week ago that was about the same way. She had taken it to a shop because of a tapping sound under the hood. The shop told her it was a rod knock and she needed a full overhaul.

A cap, rotor, and plugs later, the truck runs like its brand new.

yeah i had that issue before, except for the rich part. plugs dont seem to last very long. just swap them out

As plugs get older the electroads wear down increasing the gap for the spark to travel. This increases the resistance of the plug resulting in a weaker then normal spark. At high rpms u are asking a lot out of ur old plugs and they may not be able to keep up with the demand, and if there preducing a weak spark they may also not be producing a complete burn in the chamber, so yes check ur plugs.