O2 sensor keeps burned in my 92 Honda Civic

[David Chang]

I’ve got a 1992 civic with a 94 B16A swapped and running with a P30 ecu for 5 years. Engine has been rebuild 1 year ago and done 13000km till now. I It started with poor KPL ( 230km/L, no hard drive ) but w/o CEL on and found out O2 sensor stays rich only, also a leak from FPR because pressure dropped straight down to 0 bar in 1 sec right after engine stop so I’ve replaced both new ones, also cleaned up intake manifold, fuel injectors and spark plugs. I’m sure no leak from FPR and intake manifold but pressure still dropped down to 0 after few secs and O2 sensor had same issue after the 1st tank. So I’ve replaced new O2 sensor, spark plugs and fuel injectors also I never had hard time to start the car till now so fuel pump is working perfectly. I’ve dropped the fuel pressure to 1.8 bar ( it was 2.5 bar ) for a week and it seems okay with 300kms/Full tank so I’ve adjusted fuel pressure to 2.2 bars with full tank and then O2 burned again after I got the result of 230kms/full tank. This time was even worse that I’ve picked up the reading of 6V to 33V from O2 sensor and also w/o CEL on and no code as well. Engine harness also been replaced when rebuild engine. I’ve tried everything I could think of.. Can anyone advise me a better idea to make it done, thank you in advance.

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