Diagnose my car's problem, HELP! :(
 

The car has the following symptoms:

*Rough Idle
*Hard Starting
*Hesitation
*Spark plugs had a thick black carbon deposit along the electrodes, (I noticed this today while changing the plugs)
*Engine Oil smells like gasoline. (noticed this also today while changing the oil of the car)

I'm pretty sure the car is running rich, but i have no idea what might be causing it...
Any ideas of what might be the cause?

I checked the air filter and it looks good, as well as the new set of plugs.

BTW the car is not my Teg, is a 95' Toyota Tercel :(

just a guess... but could it be because the spark plugs are too cold?

I'm using Stock Sparks :dunno:

Sounds like a cap issue...pop it off if you havent and look at it. If you dont see anything obvious get a non flamable liquid (water prefered) and spray the cap while it is running....wires too..could be a wire or the cap itself arc-ing.

My two cents =)

Carbon-fouled plugs do indeed mean you're running rich.

Generally the oxygen sensors on Hondas can go "bad" without the ECU throwing a code and cause the mixture to be richened up. I don't know if Toyotas do the same thing but it's a guess.

It could also be a bad airflow sensor. I know on the older Toyotas that used a MAF sometimes the spring inside the sensor can loose some of its er, "sproingyness" and the sensor goes out of calibration. I don't know if your Tercel still uses a MAF or if Toyota switched over to a MAP by then but it's worth looking in to.

my 87 celica did the same thing. the MAF sensor was screwed up - but i junked that POS for ole reliable teggy!

You have been getting good answers here. The ECU could be confused due to a bad sensor--oxygen or MAS. However, there also is a chance that the plugs are not delivering enough spark to burn the fuel completely. I would check the battery cables and coil. Toyota battery cables have a history of going bad. Some will actually lose 3 volts when the engine is warm.

I had an 88 Supra with similar problems. I cleaned out the MAF meter with hot soapy water and degreaser. I re-installed it and couldn't get it to run for the life of me. Turns out there's a wire filament that is temperature sensitive hung in the airstream, somewhere in that 'honey-comb'. Once it cooled down (next morning), the car ran like it was new. Good thing, cuz' it's next drive was to the dealer to get traded in on my Teg.

Can you get any codes? Toyota's flash the dashboard lights, after jumping the service connector (at least my 88 did).

Good luck.