Your engine is OBD I, not II. Also, you could go to AutoZone or any major parts store and they'll scan the computer for free. Also, how do you know your engine is running rich?
Although possible, it's not normally the ignition that'll cause your engine to run rich. It's usually the fuel pressure regulator's diaphram has a leak and is allowing fuel to seep into the intake manifold.
That will also make your engine run rough because your computer is constantly trying to compensate for the extra fuel it's reading at the O2 sensor by shortening the injectors pulse-widths, but it's unable to.
To check your fuel pressure regulator for a leak, pull off the vacuum line that connects to the top of it and smell/look for fuel. If you see/smell ANY, then it's leaking.
If your regulator checks out, then it's possible you have a leaking/stuck open fuel injector. (But when your injectors go bad, they'll usually make the motor run a little lean)
You can also perform a cylinder drop test by pulling a plug at a time while the engine is running. If you see a noticeable drop in r.P.M.S, then you know that particular cylinder was firing. If not, then that cylinder was dead and dumping raw fuel into the exhaust.
Wednesday, January 20th, 2010 AT 8:48 AM