First off, Hello to everyone. I just bought a 2000 Z28 five days ago. I bought the vehicle AS IS from the dealer, but I got an add on warranty for 12 months. The car had long tube headers installed cats removed and all the free mods had already been done to it. I bought it from a small place and the owner operator of the place sold the car to me. The SESlight was on but he assured me that it was the headers throwing the codes and that O2 eliminators would fix that. I bought it hook line and sinker. His lot doesn't have a lift so I couldn't get a look underneath it before I purchased it. I drove it and absolutely fell in love with the power, it rode great.
Get it home and get around to putting it up on jackstands, to take a look underneath and guess what it already has the O2 eliminators on the rear sensors. The precat O2 sensors are still connected and bolted into the header. Oh ****...better see what tripped the SES light.
Take it down to autozone and a total of nine codes came up...just beautiful. Five of them are related to the O2 sensor (pre converter sensor, left bank). Its giving high voltage, low voltage, heater circuit, basically saying the precat O2 is shot to hell.
OK what options do I have here? replace precat O2 sensors at about $80 a piece. If I do that what happens if the headers fry them again, within a couple of miles. Basically what I'm getting at is do you think the headers with no cats screwed up the O2 sensors or will they likely be OK. The car has 69K on it so its believable that they could have just gone bad.
The sixth code was high voltage post cat right bank. Which has the O2 sim on it. Do you guys think the O2 sim is bad? I checked that the connections were seated properly.

The other codes were more troubling, one was for a cylinder 1 misfire and he said the other 2 codes were P1133 and P1153 fuel air metering. Is that related to the MAF sensor or do you think it is related to the O2 sensor again, sending an incorrect signal showing it running too lean or rich?
Why I am worried is that I'm pretty sure the warranty place is going to not touch anything because its all aftermarket exhaust. I don't know of any performance shops around columbus. If I take it to a shop they can't do work on it because emissions equipment has been removed and all they can do is revert to the factory emissions setup. So I think this problem is falling on my dumb shoulders and very limited cash flow. Any help or insight is GREATLY appreciated.

mitch

 

Replace O2 sensors, reset PCM. And yes O2 sims can go bad. I have long tubes w/o cats and O2's are just fine. They just go bad sometimes, buy the after cat O2's they work the same and are cheaper. Hope this helps ya.

 

Don't worry.Replace both 02's and simms and enjoy the car

 

I wouldn't replace the SIMS unless you had the codes cleared and got an SES light again from them.

 

Sweeet, you guys rock. Even though that money was supposed to go to new rubber, but it can wait till fall. Thanks for the super fast replies, I'll try that and check back.
Was the misfire likely a stored code that wouldn't trip the light?

Also would you guys try this? If the rear O2 sensors are the same as the fronts, swap the fronts and backs and see if that makes a difference? I reset the PCM by pulling the two fuses and the light came back on within 6 miles.

 

Yeah if you have the rear O2's go ahead and swap them out for the front ones.

 

Replacing the 02's doesn't guarentee you that those codes wont come back. My firebird only has 6k miles on it and I've had those 2 codes for the 2.5 years my long tubes have been on it and I've tried 2 different sets of o2's off my other cars that are fine and still those 2 codes come up. Its most likely how free flowing your exhuast is. That will make the 02's read lazy and therefore codes 1133-1153. Installing cats cured my codes long enough to pass obd2 emissions testing but they came right back after eliminating the cats. My guess is very free flowing exhaust is the cause of most 1133-1153 codes along with how far down stream the 02's are with long tubes anyway.The cure is cats or more back pressure and heat.I can tell you I've seen those codes on many, many long tubed, free flowing exhaust cars.

 

I've never seen codes on my car with longtubes or my friends cars.We did do adjustments with a MAFT when we installed the longtubes.3years later,still no codes and tuned with Edit now.