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Yeah, you're going to need something more advanced than that, or invest in other testing tools to figure out most problems with a semi modern engine. How were the plugs fouled, were they black which would indicate rich, or were they grey or yellow on the ceramic indicating lean?
They were black definitely running rich. It smells rich too. maybe thinking there might be a vacuum leak.
Vacuum leak would run lean with no other factors. You're running too much fuel, or not enough air. You're looking at things that affect that. Fuel pressure regulator, air filter, MAF, O2 sensor, etc.
Wouldn't a lean condition cause it to run rich? Unmetered air would be seen by o2 causing the computer to inrich the mixture right?
A lean condition means that the engine is not getting enough fuel for the amount of air that is being provided. If the sensors were reading incorrectly it could cause it to overcompensate for a situation that doesn't exist. Based on the symptoms you've explained here this doesn't appear to be the case. If you had a scanner and could indicate that there was evidence of a sensor being bad, we could look into that, but as of right now we have old fuel, fouled spark plugs, a previously damaged distributor cap that has been replaced and a code that indicates that more than one cylinder is misfiring. If you had other codes pointing to which sensor was providing the information the code was based on, we could point you in a specific direction but as if right now you will need to diagnose every sensor and parameter independently because you don't have a scanner with access to live info. This means diagnosing the O2 sensor, MAF sensor, fuel pressure, and vacuum in order to diagnose exactly what it's happening in the engine to cause it to run rich. You are correct in that a sensor misreading the operating information as "lean" would cause a rich condition, but the codes aren't there, perhaps the sensors are doing this and they haven't hit the threshold that would throw a code, but without diagnosis it is difficult to recommend replacing a sensor.
Okay im im going to make a trip to harbor freight to grab some tools to test the fuel pressure and vacuum. They do have a scan tool for 70$ my buddy was telling me shows voltages, or i might stop by a family friends shop to use a snap on scanner. far as voltages i could back probe the sensors.
