So the saga continues!I ended up replacing the ECT sensor, thermostat, and IAT with no change.
Found an exhaust leak, so I swapped from my sd header gaskets to the mil oem acdelco gaskets (sprayed with copper gasket adhesive), used copper rtv on the crossover pipe and upgraded to stepped 2.25" band clamps, and exhaust leak is gone.
Also went ahead and deleted my egr since I just got the code removed with the tune. Much more room now!
Broke a spark plug wire in the process, so I got a replacement set from the junkyard (8mm ultra low resistance brand from summit racing).
I'm thinking the old spark plug wires were higher resistance than the new ones because the power and throttle response made my car an entirely different ride!
However, then I got a code for the bank 1 o2 sensor and found that the fastener had come loose and melted the plug, so for a quick fix, I used a good plug and spliced the wires.... yes, I know, not the best practice. Got a new acdelco sensor on the way.
Even with it spliced for now though, I'm getting much better mpg and throttle response. No more P0420 now too since I used the spark arrester spacer trick.
So to close, I'm at 0% stft and ltft idle and deceleration, and around -7% ltft on acceleration. Hopefully the new o2 sensor helps? If anyone has anything else for me to try, I'd be very open to suggestions!
