Running Rich... - ...The car, not me.....

[makijo]

I have a question, I have notice that there is the occasional rich smell coming from the exhaust. When I bought the car, I did the whole tune-up thing ( plugs, wires, oil change, radiator flush ). The only thing I didn't replace was the fuel filter, could this be a source of the problem?? We ran injector cleaner through it also.

[ChristianL]

I wouldn't think it'd be the fuel filter, because if that was malfunctioning, it would probably cause the motor to run lean.

Off the top of my head, I'd bet it's something small like a PCV valve going bad.

But before you do anything, I recommend reading this page and see if the engine is giving you any error codes. That should at least give you a good place to start. From there, we can help you figure out the next course for repairs.

[ian]

you definately want to check the codes, but off the top of my head i'd say check the O2 sensor.

[makijo]

Okay, I read the codes and it came up "3 G signal". I know that the check engine light has not come on since I have owned the car so this could be a old code. If this is a lingering code that the previous owner didn't take care of, what is a G Signal???

[jaymond]

FYI: A few signs that your car is running rich:
-spark plugs black/sooty = rich
-black smoke from exhaust

[bill_keksz]

But, they do run rich. Any other symptoms?

[ChristianL]

what is a G Signal???

"G-Signal" is a somewhat miscellaneous error code that Mazda assigned, meaning it could be something as easy as a dirty Cam Angle Sensor (CAS) or as serious as a fried ECU.

I've noticed a lot of the early cars throw that code sporadically, but it doesn't seem to affect the engine's performance.

Just as something else to throw into the mix, how's the engine timing? I just ask since the G-signal can be caused by the CAS, which is where you'd adjust timing.

Also, I'd agree with Ian to check the voltage on the oxygen sensor. They sometimes won't give an error code when they're going bad, but since it analyzes the exhaust, a malfunctioning one could tell the ECU to give the engine more fuel.

[makijo]

I haven't checked the timing yet, I will when I get home today. I am going to replace the PCV when I get home today, it was making noise when I shook it but it seemed a bit on the sluggish side. I will also check the voltage on the O2 sensor.

[ChristianL]

Don't forget that if you need to turn the CAS to correct the timing, make sure you pop open the diagnostic box and put the jumper wire back in before you adjust the timing. That way, it'll fool the computer and give you an accurate timing setting.