shelbyfordgt
Banned
rev your truck at 2000 rpms and see if it changes. Many o sensors will get stuck like that even if they are in operating temperatures.
Hossbaby50 said:............IDLE...............2500rpm...........Limits..........Results
HC PPM...401................103..................400............Fail
CO %.....5.92................4.39................1.50............Fail
sled_dog said:Yet another worthless post being added here.
Should have seen my buddy's 02 Camaro today. Hooked it up to the gas analyzer, at Idle it was cranking out 4700PPM of HCs. Its an LS6 block with healthy camshaft, no EGR(02 didn't have them), no Cats, no AIR injection, and performance tune on the PCM.
shelbyfordgt said:might want to tell him to get another chip burned.
Hossbaby50 said:What should my O2 sensor output be in mv?
I just checked it with the truck warmed up idleing in park. It was .455-.460mv.
Harley
sled_dog said:Incorrect by far. An O2 sensor is a Piezoelectric device. It creates its own voltage through a reaction. IN the case of an O2 sensor it reacts with the oxygen in the air. More oxygen less voltage. An O2 sensor needs to be at 600*F to operate. His problem when it "cools to 150 and runs crappy" is that the O2 sensor also cooled down, out of its operating range, and the computer had to switch into Open Loop mode. An O2 sensors, does just that, it senses oxygen, thus the name. It can't pick up Hydrocarbons, so it has no idea you are running that rich, it just senses less oxygen as a rich condition. Problem is, if you have a cylinder misfire, all it sesnses its tons of oxygen, it can't pick up all that raw fuel. Thus it richens the mixture cause its thinks you are lean(lots of oxygen). Not saying thats whats happening here, just telling you how an O2 sensor works.
Open loop is when the PCM ignores the O2 sensor and just runs its own presets for fuel. This is usually a pretty rich mode, the PCM doesn't want to risk burning down your motor. A heated O2 sensor just helps you get out of Open Loop mode quicker. It really sounds like you had a bad O2 sensor or bad wiring with the three wire. There is no reason it should run anything but better with one.

4xcrazy said:Thanks for the correction there bookworm
sled_dog said:Sorry if I offended you but a pyrometer and an O2 sensor are two very different things and its important to know when diagnosing and working with a computer controlled vehicle.
sled_dog said:Sorry if I offended you but a pyrometer and an O2 sensor are two very different things and its important to know when diagnosing and working with a computer controlled vehicle.
Wait, do you know what those are?!!!?!?!? It might jsut be a CA smog thing for now.
Its cool, also sorry for the hijack.
I never think of the horn until it's too late.Hossbaby50 said:I saw the Biltrite sign truck and thought it might be you but I couldn't see threw the windshield very well and figured if it was you you would honk or something.
Harley