Little confused herew....
 

Just bought a car that belonged to one of our fellow members who passed away. The car has been sitting in a storage unit since 2016 when he passed away. I drove the car home about 15 miles, and it has a bad vibration and I could tell was misfiring really bad. I got it home hooked up my OBD-II and sure enough p0300. the thing that confuses me is this, its also throwing P0140 (bank 1 Sensor2) and P0160(bank 2 sensor 2) both state "HO2S Circuit Insufficient Activity" - So both post cat o2's. I have had an o2 go out before on my other SS so I know how it drove when it was bad, this one is acting the exact same. I'm stumped this time though because from my understanding the o2's post cat do not effect how the car runs. On top of that this car has long tubes and an off road Y so no cats. Could the bank 1 o2's be shot without throwing the codes for bank 1? Another thing I was thinking is maybe bad gas? It had only a 1/4 tank in it when I got drove it home from the storage unit. I put $20 worth of premium in it thinking maybe bad gas so this should dilute the bad gas some. didn't seem to help much. you can smell the fumes pretty bad even at idle which again leads me to think bad o2's. it also threw code P0405 ( EGR position sensor circuit low voltage) I think thats simply because the EGR was deleted. and I'm not sure that would effect the car this badly. I know my buddy owned HP Tuners and knew these cars EXTREMELY well. So any input would help me out a lot. I have done searches regarding this and have ideas on things to try, but I'm still lost on how it could be o2 related if its only throwing codes for the post cat sensors. Oh and my SES light came on and sometimes blinks...whatever that means?

If no cats, there should only be one pair of O2 sensors.

Blinking ses is random misfires. Check plugs and wires, check harness connections for coils.

Bad ground wire somewhere or corroded really bad if it was sitting for that long?

Thanks for the tips guys, After today I have the next two days off work, so it will be my first good chance to look over the car. I will check the usual stuff and post my findings. Only other thing that concerns me is there is a really loud tick sound, have not really listened to it to try and diagnose it, I really doubt its a rod or the vavle train unless the rockers are gunked up or something. here is a list of things I'm going to check first.
1) Look for any vacuum leaks/cracked hoses.
2) Check the coil packs and wires and harness
3) Check/clean the MAF/Throttle body.
4) Check O2's (even though it only threw codes for the rear's)


If all this checks out I guess I'm going to have to find someone with HP Tuners to come by and check the tune. I know my buddy tuned the car but what confuses me is I know he did the EGR/AIR delete as the EGR hole is plugged on the top of the LS1 Intake Manifold. But if he tuned the car why is it still throwing the EGR and O2 codes? Maybe he tuned out the codes but didnt delete them entirely from the ECM?

If it's been parked a few years, you may have one or more injectors stuck. Try unplugging injectors one at a time and see which ones don't make a difference in the sound/rpm at idle. I've been able to unstick injectors with an injector cycling tool. May be able to use a power probe, but when it unsticks with that, it will dump a lot of fuel.

Add to your list. Check your actual plug wires for dry rot and pull your plugs looking for fouling.

I'd be tempted to just put fresh plugs and wires on and clean the injectors. THEN fire it up!

okay so I found the number 2 plug was completely loose and almost worked itself completely out. The plug wire on that number 2 plug was shot. the little mental connector inside the boot that fits over the top of the plug was completely not attached at all. I'm guess replacing the plug and plug wires will fix this issue !

Keep us informed.