Ill try to make this brief since there are so many posts on this subject.

Had LT's installed on my car a few months ago. Right away the car didnt run that great due to loose plugs and burnt plug wire. A few weeks ago my 02 sensor on the driver side fell out. I placed it back in the header. It ran better than ever for a few days. The car started running lousy again (misfire, backfiring, running very rich), so i replaced a plug wire that had been burnt from the header. No difference.

After seeing no difference im assuming it's the 02 sensor that had fallen out. I priced some sensors that turned out to be $50-75. My question is why would i spend so much money on sensors when i could buy sims for that much? 2nd question is can i run a sim on one side and sensor on the other, or do i need to run a sim on each side?

 

If you are referring to the pre-cat O2's then you need to run both. Sims are for the post cat position and you should use two if you use them at all.

 

You have 4 O2 sensors on your car stock. One before each cat, and one after each cat. The sims are ONLY for the O2 sensors after each cat. The O2 sensors that are before each cat are used to regulate the air to fuel ratio. You cannot use O2 sims for the front two O2 sensors.

You can get the front O2 sensors for about $85 shipped from www.gmpartsdirect.com That's for 2 sensors, including shipping. I recommend that you replace both of your front O2 sensors, and either program out the rear two sensors, or use O2 sims for the rears. The rear O2 sensors will not effect the performance of the car, even if they are bad. They will only make a Service Engine Soon light come on.

After my header install, my car ran super rich until I replaced each of the front O2 sensors. This is a common thing when installing headers. My car has been great ever since, about 5000 miles later.

Dan

 

Thanks for the input and great link. I think ill give the new 02 sensors a try and work from there. Ill be completely relieved if that does the trick, im just scared to death of the opti goin out on me.