Hondata

Model: 2020 Civic SI

Mods
-27Won intercooler

Symptoms
-unresponsive throttle
-no boost unless I hold the throttle for 5+ seconds
-no more intake sound or blow off sound (wastegate)
-decreased engine and exhaust sound
-rough idle at about 400-500 RPM
-exhaust makes weird bubbling sound when the car turns off, as if there's water or fluid in the exhaust, but this could be caused by being too gentle on the throttle
-knock control between 80% and 99%

Diagnostics so far
-Boost leak test with no findings
-fully replaced turbo and wastegate with no improvement
-untuned the car with no change
-replaced stock intake
-cleaned MAF
-replaced downstream O2 sensor
-used fuel injector cleaner
-replaced MAP
-compression test, all 190
-replaced spark plugs

The issue
This issue has been unresolved for about 2 months now. It started after I put Lucas 3x Octane Booster in my car after an oil change because I thought it kept your engine health good. Anyways, I was highly misinformed and regret it. For a while the dealership and I suspected a boost leak because I'm not building boost, but now I believe the octane booster ruined some sensors and stuff, maybe clogged fuel lines, maybe my catalytic converter. I just replaced the downstream O2 today because it was the cheapest, next is the upstream, since that one is covered in more orange powder.

Many people say octane booster doesn't hurt but it seems like it definitely does. I just need help analyzing my symptoms and my logs to determine what the issue could be, or to figure out what sensor could be bad. Or maybe I have to replace the whole fuel pump assembly, maybe I have to replace the fuel pressure regulator. I just need some guidance because I'm lost and the dealership has no idea what they're doing. I'm very desperate to fix this and be able to drive normally again. This issue originally caused my turbo to crack, which I have no idea how. Unless my car is opening the wastegate sooner to reduce load, and thus overspinning the turbo.

It's also highly possible that my loss of power is just from such high knock control, maybe because the O2 sensors are coated in octane booster. But I'm not sure what else could cause this.

If you return to stock and the problem does not go away, then you have a mechanical issue with the vehicle and it is unrelated to the tuning or Hondata.

Both datalogs appear to have been made with the ECU returned to stock.

But the sensors should still log as normal and provide insight?

After replacing downstream O2 sensor my knock control is now at 55%. But I'm still experiencing loss of power and low boost.

Is your CAT clogged?

The dealership said the cat was probably clogged and so they replaced it under warranty, but the issue is still persisting. I actually think I just cracked my new turbo the other day when it was 93 degrees, so I think my turbo is overheating.

My upstream O2 sensor was orange when I checked it, but I don't have any engine codes. Is it possible the O2 could be inaccurately reading exhaust and opening the wastegate too soon or something without causing a CEL?

I would recommend that you return the ECU to stock and see if the issue persists, if it does then it needs to be diagnosed by the dealer.