Ok, just ordered my O2 simm from the fastman.
heres my question, how can i easlily tell if my truck is actually running lean right now?
i know for a fact it has less ***** on the freeway, to the point i need to ride 4th to go over a slight incline. and it didnt do that a couple weeks ago
and sometimes when i let off the gas in gear It backfires out the exaust.

 

Backfiring is usually a good indication of a lean condition. Keep in mind it has been much warmer around here so the power loss you are feeling could just be because of warmer air temps....however that shouldn't cause any backfiring. Have you tried resetting the ECM/PCM after adding the O2 sim? It could just be that the computer hasn't readjusted for the change in signal from the O2 sensor. Why are you using the O2 sim? It might help me understand a bit more what might be going on...

 

he prolly got rid of his cats...which i'm doing tomorrow
but i'm only zip tying the o2 sensors to the frame rail and we'll see what happens

edit: maybe i'm just ignorant, but i thought that only the pre cat o2 sensor had anything to do with your air/fuel ratio? and the post sensors only looked for a change...idk

 

I would hope he didn't get rid of his cat...we have e-check here...although it isn't in every county. I believe N.Ridgeville is in a county that does emissions testing though.

Honestly I'm not real familiar with the dual O2 sensor setups but you might be right ziggy.

Maybe somewhat off subject but...personally I really don't see there being a huge benefit to removing the cats...maybe a couple horses at most. Besides you can get high flow cats from summit racing for under $100 and remain fully legal.

 

yep high flow cats are cool, i run a 3" on my SVO. but my cats are coming off tomorow, i mean they are the gay lil pre cat ones heh. no emission checks here, but when i need to i will get me a magnaflow cat

 

You can smell the gas coming out the exhaust I think. Depending on the mixture... But you usally don't get a complete combustion and you will hear it running roughly... or more gut less... I would like to see o2's that you can adjust the settings to set your own mixture like doing your settings on a dirtbike...

 

my cat was forcibly removed by a chevy van in december, i don't need e-check until next year, so it'll get a cat closer to then.
i'm putting a manifold back exaust in before then anyways.
the comuter reads the two sensors and adjuststhe mix depending on what it sees

 

Yeah, removing the converters doesn't really get you anything. A modern catalytic converter doesn't take but 2-3 horsepower -- nothing you'd notice. In addition, vehicles are designed with them in, meaning the loss of that little bit of backpressure can wreak havoc depending on other systems on the engine (like what type of EGR the car has, etc). It can also negatively affect your fuel trims because the PCM doesn't see the level of exhaust polishing that it expects. Just leave the cats alone.

Regarding the O2 sensor, you can tap into the signal wire of the O2 sensor and "see" what the O2 sensor is seeing. You should see the voltage constantly bounce back and forth between about .200 mV and .800 mV, with .500 mV being "stochiometric". I seem to recall that a higher mV reading indicates a lean condition, and a lower mV reading a rich condition, but I don't remember which is which.

 

the current after cat sensor was ripped in half, so i guess its reading nothing.
i'll find out when i get the simm in if it makes a difference

 

Well if you are running lean, there is more going on than just your rear o2 sensors. Although some people think otherwise, Dodge and most other auto manufacturers do not figure in the rear o2 sensor signals to the air/fuel feedback equation. The rears could be bad, or missing, cat or no cat and it makes no difference to the fuel mixture, and there is no "limp-in" mode caused by rear o2 sensor problems. If the rear sensors are in the exhaust pipe and no cat is present, the PCM sees no difference between the signals from the front and rear sensors which is why the MIL comes on. The trick I did on my truck works prefectly fine. I get an occasional "slow response" code for the rear sensor but my MIL light never comes on and stays on, and no air/fuel mixture problems. I would hate to be the one to say you wasted your cash, but you did.