cr0y

After a few weeks of driving my new (well 1999) z28 m6 i am still getting terrible gas mileage and the car runs odd. I notice under throttle in 2nd gear the car will hesitate and run just generally off. I had a few error codes for o2 sensors, but now my SES light is off. I am going to replace the o2 sensors (all 4 of them?) but i am not sure if this is contributing to my shitty gas mileage and poor performance. Does anyone know why my SES light would have gone off? I am averaging 11 mpg even when i baby the car. Please help, I do not know what to do any this is getting expensive to drive.

99CamaroSS_

have the rear ones turned off, and replace just the front ones.

who did you buy the car from? mods on it? previous mods?

cr0y

I bought it off a guy who took what I can see to be really good care of the car. I live in a chevy family and do our research before we buy a car. The only thing done to the car is a catback borla exhaust. What do you mean by having sensors turned off, what will this do?

I appreciate your time!

cyphur

iTrader: (10)

you can delete the rear o2 sensors from the PCM, but its usually only done when you remove your cats. they won't throw codes anymore but when you delete them w/cats on the car, you'll never really know when the cats go bad til you smell them.

cr0y

So where are the sensors that would affect gas mileage and performance located?

BAD FNZ

I had the same problem... But my rear O2's are deleted, replace the two front O2's and you should be good to go..

BLASTER

iTrader: (4)

Your rears only meter Cat efficiency. Your front O2s are what actually meter the A/F. For example, If you are getting p1133/p1153 (like me ) then your front O2s don't switch fast enough to adjust the fueling and you suffer from running in open loop where the PCM adds fuel (for saftey) and thus you drink gas.

Cal

iTrader: (1)

Yep same thing happening to me. You can replace your front O2's with Vette O2's and they will stay hotter, Bosch p/n 13111. I still have the problem though; thinking of ceramic coating my headers to see if that helps.

tkz28

did you clear the service engine light
and if so what code did it read

fnbrowning

Cal, this is interesting.
Give us a little more info if you can on why the Vette 02's run hotter, and what this means for us. A linkie to another thread or article would be great.
Is this a worthwhile mod for ppl that have Long Tube headers?

Thanks!

cr0y

How can i go about having the rear o2s deleted? If it requires a 500 programmer then that is out of the question :-/

I am in pittsburgh pa, if anyone has hptuners or something and is willing to help me out I will make it worth your while

cyphur

iTrader: (10)

fnbrowning, IIRC they have a more powerful heater in them, and run at a slightly different voltage than the f-body o2's. i'd think b/c they're longer to begin with and so they heat higher b/c they're farther from the engine. f-body o2's weren't meant to be placed so far back for optimum performance. given time they wear down.

Cal

iTrader: (1)

They run hotter because they have higher wattage heaters. They are designed that way because in a Vette, the O2's are farther from the engine. It means fewer low activity codes if you have headers. They also have longer wires on them which is nice after you install headers. Do a search over in the PCM tunning section and you will find a lot of threads on this.

tkz28

what were the error codes, this same thing happened to me and it turned out my cats were bad which made the rear 2 o2 sensors throw codes too