Rich or lean ?

[RJ-92]

What is the best way to tell (obviously short of using a dyno with o2) if the car is running rich or lean? I am thinking mine is running somewhat rich. It sometimes runs a little rough @ idle.
Once in a while it tends to flood on startup which would lead me to think this. It won't want to start right away then I shut the fuel pump off and it fires right up.

I haven't changes the plugs in like 50k. Could I just need new ones?

 

[JMoff92]

Ya, I would say that you should change your plugs and wires. I don't know how to tell if a car is running rich or lean though.

 

[MotoArts]

Spark plugs with gas soaked or sooty black electrodes (center cone, not the metal ring with the threads) mean rich. White, "squeaky clean" looking electrodes means lean.

In my experience, bad/old plugs will not make an engine rich or lean, they'll just misfire. A computer code check might tell you which component is failing. Expect to find something like faulty O2's, EGR valve or sensor, fuel pressure, faulty injector(s), clogged air filter, etc.

 

[projectSHO89]

You can directly measure whether the engine is running rich or lean by monitoring the O2 sensors (assuming they are good). This is not a trivial task.

As mentioned, reading the plugs can give a very good indication as to the health of your mixture and engine.

Steve

 

[silversho89]

Get it scan tested. There should be a voltage reading from the O2's that will fluctuate back and forth from rich to lean. The voltage out put should fluctuate from .4 volts to .6 volts. The highet the voltage the richer the engine is running. Hope this can help.

 

[SHOZ123]

Also if you get it scanned you can see the fuel map data the O2s have set up. This will tell you whether you are running on the lean or rich side exactly.