If I have longtube headers and an ORY, do I need o2 sims? Or can I drive it around without them?

 

you could, but you'll get an SES light.
O2 simms = no SES

 

^ What he said

 

yup no sims = ses light, and if i'm not mistaken your car will run like crap

 

^
is mistaken...

correct you don't need O2 sims.. they prevent the SES... but the rear O2s are ONLY used for emissions purposes...

 

"and if i'm not mistaken your car will run like crap"

Yes, this is a misconception. Performance will not be effected in anyway when running without rear O2 simms. They just turn off the SES light by fooling the PCM into thinking that there are indeed properly functioning O2 sensors hooked up.

 

I thought so. The front ones are what allow the car to enter closed loop. Alright, I can deal with the SES light.

 

My car was running really rich and sluggish. When I installed my O2 sims the car really picked up, the idle sounded different, the rpms were lower at idle. I was running a 11:1 A/F ratio, and that has since leaned out. I know from first hand experience that the car did run like crap w/out sims, I was told it was in a sort of "safe-mode" and I think they were right!

 

You can run the o2's w/o the cats.
I had no simms w/o cats for a month.
My car is m-6 so it was easy to do the following.
Never let the car idle a steady rpm at idle.
Every 5 seconds just kiss the gas pedal & rev it up a tad.
This will keep it from running the catalyst monitor, which it starts test hot at idle.
The readiness monitor will always read "not ready" but it will not turn on the light.
If you forget & let it idle it will figure it out in a hurry.

 

i was told that you can make a o2 simm with a simple resistor setup can any one back that up?

 

What about Cat Over Temp Protection (COT)? I heard this will make the car run really rich. Is COT a random thing or does it happen when runnin without sims?

 

COT is a high rpm thing.
The o2's play no part in this.

 

What triggers COT?

 

No....

The PCM wants to see avarying voltage. If it seees a steady voltage it will throw the light because it thinks that the sensor is bad and not responding to the varying AFM coming out of the cats.

Additionally, the heater circuit for the O2s needs to be completed, or..... another light.

Gordon
www.provenperformanceconcepts.com