Random Misfire, fine after reset, comes back a day later
I need some help with my car. it's a '05 156 JTS 2.0.
I recently installed a small turbocharger, removed one cat and relocated the o2 sensor down a little. On top of that, I added a Unichip to adjust timing and fuel.
The car drives really great for a day or two, then after that it just starts misfiring at around 2600 rpm, then after that keeps on misfiring on cylinder 2, 3 and 4, finally throwing a MCSF and MIL with p0300, p0302, p0303, p0304.
Resetting the error codes results in a fantastic drive, up till a day later, when it all kicks in again. The unichip was working fine when it was normally aspirated, and putting in all zeroes values for timing and fuel (i.e. no change to any timing/fuel) did not change anything.
I'm guessing this has to do with ECU learning, and not a mechanical fault as the car drives great with reset values, and over the course of 1 day, develops long term fuel trim of 40-50% and short term fuel trim of over 60%, and eventually goes back to it's bad habit of misfiring.
the boost is set pretty low, at 0.3 bar for now.
I don't think it's the plugs/coil packs/ignition system, as the car seems to drive great everytime the values are reset, and slowly "learns" some bad habits and misfires.
I'm chasing whether it's the unichip, or maybe placement of the o2 sensor...
Hope some of the experts on this forum can help with some suggestions? Thanks in advance...