Car running lean?? Faulty O2 sensor or what??

DSMRevolution · 12-15-2002, 09:09 PM

I just installed a Autometer Air/Fuel gauge (I know...). The car is running, to me, what looks to be rich. It is shooting unburned fuel out of the exhaust pipe. I got a pile behind my car in the garage! Also the air/fuel gauge says that I am running lean. It is on the first mark in lean at idle. Sometimes, when I rev it, it will go up maybe 2 marks. I have not driven the car yet since this install.

Does this sound like a bad O2 sensor or what?

Our vehicles do not have a heated O2 right? Just the O2 sensor in the O2 housing?

Thanks

markmakeitso · 12-15-2002, 11:14 PM

i don't see a test pipe in your mods, so i'm assuming you have a cat on your car. that much fuel going through a properly functioning cat will be super hot, i've even heard of cats melting due to a non-firing cylinder. are you sure it's gas coming out of the pipe?

i don't think dsms have heated o2 sensors, a heated sensor usually has more than 1 wire leading to it.

DSMRevolution · 12-16-2002, 07:09 AM

No, I am not sure its gas or not. I still have the cat. What do you think? Thanks.

It shouldn't be that lean at idle I think...

DSMRevolution · 12-16-2002, 02:23 PM

Nobody knows??

4G63_Mirage · 12-17-2002, 09:29 AM

It is most likely oil coming out of your exhaust, not gas. You said you haven't driven it, try driving and see if it runs lean while accelerating. The people that I know that have a A/F gauge does not run above lean until acceleration depending on how much boost is being ran. Try this and let me know whats up.

BOOSTEDPSI1 · 12-17-2002, 11:45 AM

From my knowledge of those blinky light A/F gauges is, if your guage bounces back and forth at a pretty constant rate your O2 Sensor is ok, however if there is no movement on the gauge that means your sensor is dead.

Most O2 sensors only last 60k so if it is past that point you may want to change it out, also it is a good way to increase your gas mileage.

I hope this helps.

DSMRevolution · 12-17-2002, 09:10 PM

Ok thanks! Why would oil be coming out of my exhaust? I will drive it tomorrow and let you know if it bounces back and forth at all on acceleration. And it is about time to change that O2 I think! Thanks again, Ill let you know tomorrow

hose101772 · 12-18-2002, 12:41 PM

turbo dsm's use heated o2 sensors with sensor ground-4wire,atleast all that i've ever seen.is the ground black where your exhaust is?carbon and water more than likely.not a bad thing just part of owning a overly rich dsm.a/f meter lights should "bounce" during cruise,showing rich under boost.during drive,if the lights dont move after a minute or two and you're sure you've connected to the proper sensor wire,your o2 is dead.good luck

DSMRevolution · 12-18-2002, 02:17 PM

ok thanks. Yea, the ground is black where the exhaust spits out. Wouldn't a dead O2 sensor throw a CE light? thanks

FastRthenU · 12-18-2002, 05:32 PM

If you have a dead o2 sensor. It will send the computer into an open loop. Meaning it no longer know's what the air-fuel ratio is anymore. so as a safty messure it runs the car really really rich. So that you do not lean out the motor. So if its faulty sensor you should be running rich as hell

DSMRevolution · 12-18-2002, 08:44 PM

thanks, but why would it say its running lean on the gauge?? Just cause the voltage is so low?

FastRthenU · 12-19-2002, 12:39 AM

i cant really help you with out seeing the car or more in depth info. what makes you think it is running rich? what is the gauge doing when at idle/cruising/wot? need more info

The air fuel gauge should go back and forth form lean to almost if not rich at idle. it does this so you dont burn out the cat. It is suposed to do that. When you driving at a steady speed the gauge will also bounce back and forth. But when you are almost and wide open throttle, and up to full throttle it should go right into the gree and not move out of it. If you are in the red then you are running lean.

DSMRevolution · 12-19-2002, 10:51 AM

Ok, thanks for your help again! I will try to get everything back together again today and take it for a drive. That way, I can get you some more information, and myself more info too. I'll post it here again. Thanks

Tevenor · 12-19-2002, 10:56 AM

The 'A/F Guage' reads off the O2 sensor. If the O2 Sensor is dying, then the reading that you see 'lean' is the same as what the ECU sees, so it richens it up and hence you run rich. Simple isn't it?

lowridin2g · 01-01-2003, 03:09 PM

ok just hooked up the af guage. now when the car is at idle, it jumps around, started at stoich, bouncing a little then as it idled for a few it was bouncing from lean to stoich to rich, and kept doing this. now when i gave it gas it went all the way over to rich.

took the car for a ride and when i was light on gas pedal, it jumped around from stoich to rich, when i got on it it went rich and when i let off the gas and just cruised it was all the way lean.

just hooked mine up today, im guessing that is normal by the above responses, is it not? i also have the autometer blinky one. should this be all the way lean when giving it no gas and driving?

DSMRevolution · 01-01-2003, 05:57 PM

I believe that is normal. Mine is working fine and does basicually what you discribed above. I just wasn't letting the car warm up enough before. O2 sensor showed lean untill it was warmed up.