i have a s1 pcm and i do run a lot of leaded race gas, would that lead have an effect on my downstream o2 sensor? already changed upstream which looked like crap and wondering if i should changed downstream since i haved a s1, no CEL codes by the way.[/align]
i have a nw e-cutout which at times i open/closed depending on accassion, but i run 110 race gas on occassions and every other weekend, last weekend i had half tank of leaded 110, even though i dont get a CEL will a bad downstream o2 still make car run like crap?[/align][/align]

 

Good / debatable question... The common understanding is that with the staged PCMs the downstream O2 is pointless. However, just recently, I've read a few people saying that the PCM still uses itto calculate aportion of the fuel trim (not sure why). I have yet to validate this statement though. There are alot of people that have the sensor hooked up, but ziptied to the underbody, which would be just as good as not having one as far as calculations go and they don't seem to have any problems. If you have the proper monitoring devices and everything looks good I wouldn't worry about it.

 

that's my concern, i changed the upstream which was looking bad i am guessing from all that lead crap, and downstream looks just as bad, and i have never changed none of the o2 sensors since the 2 yrs i had the car, car is running poor, at times theres like a delay for 1 or 2 sec when i give it some gas but at wot its not that bad, also lately my gas mileage sucks, i changed plugs and wires so thats out of the equation

 

What kind of downpipe you running? I assume it is catless, but have to ask.....

 

needswigs dpwith electric cutout at times i have it en and at imes i close it

 

To my inderstandimg the lead does coat the 02 sensors causing them to fail, glad to hear you dont have a cat on, that would totally be destroyed. Well I guess the car would run like crap it what Plan B said if it still uses the downstream 02, its if getting a false signal due to being coated then it could put cause it to run different. Throttle response will be different when the computer is not getting the correct signals from the 02 sensors.

 

here's another question that i have to ask.....do you have something to be adjusting timing with? if not you're wasting your money on race gas, it won't help and in fact might even harm you due to it being harder to ignite.

 

not really, i have an safcII, and the car was dynotuned with 2 files, 1 being for street (93 tane) andfile 2 forleaded race gas with much higher boost, that's bout it, i have an msd dis 2 box that i'll be installing pretty soon

 

then stop buying race gas, it's not helping you. unless you have something to change timing/ignition with (ie: aem fic, aem ems, sct)you're completly wasting your time. just use w/i, it's much cheaper and will actually help you.

race gas has a much higher combustion point than regular 93, especially if it's leaded. this makes it harder to burn. if you aren't controlling ignition and timing, you're not completly burning the gas and it will in the long run hurt performance. turning up the boost on race gas is a bandaid. all the higher octane is doing is preventing detonation at higher boost, but w/i can do that for a lot less money and much more efficently.

 

forgot to add i do have w/i as well, do you think i will feel any difference in performance with a msd dis 2 box, i mean i already have it just never had the chance to install it, other then the 2-step of course will it help burn the fuel more efficiently? and can i use stock coil with the msd box??