Got a few questions about exhaust, idle, O2 sensor and oil.

[CBT8503]

Yesterday I finally got my full 3" O2 eliminator RNR turbo back system bolted on. The battery was disconnected and I replaced the O2 sensor with a brand new one (was a universal and had to splice the wires). I started it up and loved the sound, but the idle would go down to 100 or lower and it went dead on me when i shifted into neutral coasting to my street. Started it up this morning and the idle was steady at 1k RPM's. Is the computer just trying to get used to the new mods? Also, i'm currently running full synthetic motor oil. I was thinking about going back to synthetic blend but I'm not sure if that's a good idea or a bad one. My car has about 76k miles at the moment, and the oil was a little short of full the last time the oil was changed. What do you guys think I should do?

 

[bfdahl]

Usually when you unplug the battery you idle will be weird becasue you computer resets and the idle control motor gose to its reset position and your thottle body is dirty and now the air cannot pass though properly. I usually clean mine if i dissconect the battery.

as for the 02 i would never use a universal 02. the factory says splicing the wires can give false readings due to higher reisistacne in the wiring.