I get back home and I'm looking around the engine bay to see if there was a fuel injector plug lose, plug wire lose or some sensor lose. Didn't see anything abnormal, but after going into closed loop it starts to misfire and run like general crap. Then I get under it to see if there is an exhaust leak. That is when I see the cat converter glowing (probably from the rich AFR in 4-5). Shut it down and pull the codes. P0171 (Bank 1 fuel system too lean) and P1075 (Bank 2 fuel system too rich).
Start it back up and log from the FIC. Shows that O2 sensor #1 is showing lean and O2 sensor #2 is showing rich. I run it just long enough for the O2s to come on line. I have the FIC reflash in the back of my mind at this time, but its late and my tools are at the machine shop from earlier. I do some research on these codes and everything from an intake manifold or exhaust leak, vacuum leak, burnt valve, burnt piston, etc come up. MAF sensor on fords with both codes present.
Go to the machine shop this morning (drives fine until it starts reading the O2 sensors in closed loop) and after I finish the vehicle I was working on yesterday I start on mine. Test fuel pressure, test compression (~160 psi on all), see if every injector is firing, make sure that the O2 sensors are connected to the correct harness plugs, check for spark, etc. I check the plugs as well and 1-3 were clean and 4-6 were black with carbon, which went along with the codes. Everything checks out so I bypass the FIC. It clears up and runs fine. I reflash the FIC to the Z107 that I was running, reset the PCM to clear it of the garbage fuel trims it learned and its back on the road. Its just hard to imagine what the FIC was telling the PCM to make it do this.
I don't understand why the Z104 didn't work for me, but glad it was only that and not an engine problem. I think the engine is fine as there was nor much load and it wasn't driven long like that. However, I don't know if the cat converter is still good or not. I do plan on doing a back pressure test later.
BTW, the descriptions of the FIC flashes:
Firmware Hex Files:
Z files (Handle fueling and firmware):
- Z104.hex: Used on older vehicles where multiple injector pulses are not present
- Z107.hex: Updated version of Z104.hex, used for Scion TC
- Z110.hex: Used for newer vehicles that have multiple injector pulses. Faster response time than other hex files.
X files (Handle the calibration and PC software):
- X131.hex: Version 1.31 firmware
- X300.hex: Version 3.00 firmware
- X3.81.hex: Version 3.81 firmware updates include: ability to use TPS as a load option in the Fuel map, acceleration enrichment pump, and maximum RPM raised from 12,000 to 17,000 RPM
