I just installed rockers and adjusted the lash, and the car was running fine. The only thing I didn't like was I was seeing the Left long term fuel trim at 122 and the right at 133. So I decided to switch the o2 sensors and see if it followed them. I needed to elongate one of the sides so I spliced in wires to make the plug longer. I spliced in on the sensor side, not the harness side. I put a little bit of antiseize on them and put them back in. I turn the car on and let it idle for a few minutes. The long terms got worse. The left side was like 83 and the right was 180. It was shaking and I turned the car off. Any ideas as to what is going on? It seems it wasn't the O2 sensors because the rich and lean condition stayed on the respective sides even thou I switched the sensors, but now its much worse than before. Please help fellas.

 

Are you sure you are looking at the long term fuel corrections? Typically, stock programming (and most aftermarket tuning) limits them from dropping below 108, or going above 160. In what cells did you observe the BLM's you posted? Why did you cut the sensor wires - generally not a good idea? How much anti-sieze did you use? typically the sensors are packaged with conductive anti-sieze already on them, and applying too much conventional anti-sieze can damage them.

 

My scanner doesnt allow me to see what cells I am in but only gives me the long term fuel trims amongst other readings. I have an aftermarkett tune and I think the guy changed the max and min fuel trims. Before this problem I had the driver side o2 sensor spliced in to make it longer and saw now problems. Now both are spliced, because I swapped them. I don't believe it is a wiring issue because the sensors are working. The sensors only had about 4-5 threads so I just coated them with a decent amount of antiseize. What would a damaged o2 sensor be reading because I can watch the numbers change and try and identify if they are not working? Since I was not installing new ones should I have installed them dry or just used the slightest dab of antiseize?

 

Did you use any penetrating oil on the sensors to allow you to get them out?

Split BLM's at idle (Cell 16) are not unusual with a larger cam, but the LT4 HOT cam should not present a problem with split BLM's.

If I understand the sequence of events, before you adjusted the valves, you did not have the problem with split BLM's. Only after you adjusted the valves (and did nothing else) did the problem show up. Then, when you switched the O2 sensors (and did nothing else), the problem became several orders-of-magnitude worse. I'd start with new O2 sensors, and a new harness extension, so you don't have to cut the sensor wires. That eliminates any problems you may have created by the way you handled the sensor swap. Then back track to how you adjusted the valves, and whether that might have caused the initial problem with the BLM's. Sounds like the valves may be too tight on one side, causing excessive overlap and incoming air to exit with the exhaust gasses.

 

I did not use any penetrant during removal. I did some searching and saw that it was common for guys to have problems with o2's after splicing wire in. I am going to get a new pair of 02 sensors. Since the sensors will be new, you said that it would have something on the threads so i won't put anything on during install, but what if I ever pull them again? Should I use a tiny bit of antiseize or nothing at all?

Also, I was looking at harness extensions and the smallest i saw was 12". I have midlength headers and the pass side does not need an extension, but the driver side needs about 5". I don't really think the extensions are worth it for me since they come in a pair. Do you think it would be a good idea to splice into the engine harness side of the driver side o2? Or just suck it up and zip tie the extra length of the extenders?

 

You need a quality splice in the harness wires. Only you can know if you have the skills to make a solid, low resistance splice.