I had MadZ28 program out my o2 sensors but I am wondering if thats a good idea. I did it because one of them wasn't working. Should I buy a new one and have computer changed or what? I need pcm done for new gears anyway so thats no biggie.

 

Well, it is hard to pass emmisions w/o o2 sensors. It will run just fine w/o oxygen sensors. Alot of times, with a big cam, you will get added cam surge w/ o2 sensors.

 

No emissions here. What exactly do o2 sensors do then?

 

how is your car calculating a/f ratios if you have no O2 sensors??

 

that is what i was thinking. I understand that it will make the computer think they are there and right on the money but what if you are running a little rich or lean? The computer will think everything is fine and not adjust as needed. Right? Don't sound like a good idea to me.

 

The front O2's do the job of keping the motor running rich or lean. All the rear are there for is to make sure the cats are doing there job. When the comp starts seeing that the front O2's are reading the same as the rears it turns on you CEL b/c the comp thinks the cat is bad or not there.

 

Haha get them put back in man. O2 sensors are what sends the PCM the readings of oxygen in the exhaust stream during open loop, without them sending the info the car is either going to run how it wants, rich or lean. I don't know why you would take them out, if one isn't working replace it.

 

Yes, you need your front ones, I though we were talking about the rears. A new one is only like $40

 

His sig says 1994, so he has no rear O2s.

 

I think it is closed loop. Yeah you don't need the rear ones, only the front ones.

 

If i'm going to be putting LT headers on a 97 Z28, i only need the front 02 sensors then? I just want to make sure. Should i then get 02 sims for the back two? Thanks in advance

 

Yes you need the fronts but you can add sims for the rears.

 

I would check with MadZ28 to make sure you know what he really did. I find it a bit hard to believe he programmed out the use of O2 sensors in your case. I bet it was more like you filled out a standard form, which had a checkbox on it for programming out rear O2 sensors (which would make sense on a newer car). But yes, get your O2 sensor replaced either way

Dave

 

Im pretty sure he programmed it to run open loop constantly. I thought it was running rich so I will definitely get new sensor and have it put back in pcm. Thanks for all the help.

 

it would be programmed to be in open loop. you car runs in open loop when you first start it up and when you are at wot. I open loop you just have preset parameters and the 02 don't adjust anything.