What causes rich?
 

I think my car is running rich. (Pretty sure!) My gas mileage is terrible, 12 mpg city, that is driving regularly and never up above 2500 rpm. I'm doing a tune-up as soon as I can be outside more than 3 minutes and not get frost bite, gotta love Chicago. Right now it's a chilly 0*. Anyways, I'm planning on o2 sensors, cap, rotor, wires, and plugs. Is there anything I should do like clean the MAF that would cause me to be rich? ~Brian

whats fuel pressure set at?

I don't have an adjustable regulator so correct me if I'm wrong but is factory 38? ~Brian

If you are running a 160 thermostat that will also make you run rich. You should invest in a Aeromotive FPR and fuel pressure gauge then you will have total control.

Dark_5.0: I'm running a 180* thermostat. I looked into it before putting one in. Everybody said 180 was perfect for a street car, and 160 would cause problems, just like you told me, so I stayed away from that. ~Brian

Have you pulled your codes yet? That may give you a starting point. The EGR is another thing that can cause you to run real rich. But before you go too far pull your codes and see what the computer thinks is wrong...:cool:

Pulling codes is a good idea, I'll try to do that this weekend. Thanks ~Brian

Bad O2's will cause you to run rich as well.

FYI....never never never try to clean an MAF... You'll probably break it..they're very sensitive pieces of crap. :D

I thought I read about guys cleaning them with q-tips and gaining some idle and acceleration qualities, maybe I'm wrong though. ~Brian

cleaning MAM
 

HUH??

Yes, you can clean your MAM. Definitely clean it...especially if you run a K&N air filter. The oil from the air filter can sometimes get on the little wires that are on MAM sensor itself. It is safe to clean it with q-tips and some rubbing alcohol. Just becareful not rub too hard. Very easy though.

Really?? I was told never to clean one..never to even yank the screen off because the wires are so sensitive that even tapping them or anything will break the MAF unit or cause it to read incorrectly. Then again, that was on a GM site and for some reason, Chevys and Pontiacs are notorious for going through MAF's like nothing at all. I know a girl with a Firebird that's gone through 5 MAF's in 1-2 years.

I might have to do this one then!

What causes rich?

Stuck EGR, bad fuel regulator, stuck O2, pinched return line, bad coolant temp, LOW on coolant, Map sensor, mass sensor dirty or bad, sticking injector, intake air temp off(off by 10-15 degrees will make it run rich), dirty air filter and sticking thermostat just to name a few.....

I plugged a few plugs and after 1 year, they're clean! So does this mean I'm not running rich and just getting really crappy gas mileage?! It isn't a huge factor but some of friends are getting almost double the gas mileage with mild mods, such as mine. ~Brian

In order to get horrible gas mileage, you have to be running rich unless your car has the mods to justify running rich. Not running rich but getting bad mileage means the car is getting more air to be able to dump in more fuel, and also has the ability to burn all of that off.. And hey, your mileage can't be as terrible as mine... With a cam and a 4.11 rear, my best guesstimate is 8 mpg city. :D