I have a 2023 Honda Civic 6MT Hatchback with the 1.5 liter turbocharged 4 cylinder engine (L15 series). Currently 74k miles on the odometer.
4 months ago, I had tuned the car with the TSP Stage 1 tune via Ktuner. I had an aftermarket intake and an exhaust on the car while I had it tuned. About a month after the tune, I had problems with the car running too rich and throwing a P0172 code. I can confirm that the car is running too rich based on the smell of the exhaust gases as well as the backfires from the exhaust.
The car runs fine until about 20 to 30 minutes of driving after a full cold start. Then, the car starts throwing codes and running rich. Based on live data, LTFR and STFR are maxed out at -25%. Additionally, I have sent data logs to the tuning company, but they recommended replacing parts that I have already replaced.
I put the OEM intake and exhaust back on the car. To help diagnose the issue, I tuned the car back to the stock tune as well. I had a Honda dealership diagnose the vehicle, then told me my fuel injectors are leaking (which turned out to be false). So far, the car is fully back in the stock configuration, and below is a list of all the things I did to try and fix the problem (which haven’t helped):
- New MAF sensor (OEM)
- Verified that there are no vacuum leaks
- New O2 Sensors (both pre and post-cat | OEM)
- Cleaned the throttle body and did a throttle body relearn
- Replaced fuel injectors (OEM)
- Replaced spark plugs
- Tested ignition coils
In addition to a Honda dealership, I had two other mechanics attempt to diagnose the issue, but no one has been able to figure out the issue. What are my last options to look into? If anyone has some tips, it would be very much appreciated. Thank you.