BLACK SMOKE FROM LEXUS RX 300

Vehicles before 1996 will sometimes emit black exhaust smoke during the first start up of the day, this is normal as long as it clears up once warm. On vehicles built after 1996 , Black exhaust smoke is not normal. This is an indication that the engine is not burning the fuel efficiently and or the fuel injection system is trying to force to much fuel through the engine.

Possible causes range from a failed O2 Sensor, Injector Stuck open, or failing MAF Sensor. Some times a simple tune up is all that is needed.

If this was not happening before you changed plugs and cleaned injectors… Why did you? and it might be that one of the plugs had the gap closed and not burning the fuel, the O2sensors are covered with injector cleaner and the engine hasn’t been run long enough to burn it all off.

If the check engine light is on, check the codes first and post them back here.

P1135 LEXUS – Air/Fuel Ratio Sensor Heater Circuit Malfunction Bank 1 Sensor 1
Possible causes

– Faulty Air-Fuel Ratio (A/F) Sensor Bank 1 Sensor 1
– Air-Fuel Ratio (A/F) Sensor Bank 1 Sensor 1 harness is open or shorted
– Air-Fuel Ratio (A/F) Sensor Bank 1 Sensor 1 circuit poor electrical connection
– Faulty Engine Control Module (ECM)

P1155 LEXUS – Air/Fuel Ratio Sensor Heater Circuit Malfunction Bank 2 Sensor 1
Possible causes

– Faulty Air-Fuel Ratio (A/F) Sensor Bank 2 Sensor 1
– Air-Fuel Ratio (A/F) Sensor Bank 2 Sensor 1 harness is open or shorted
– Air-Fuel Ratio (A/F) Sensor Bank 2 Sensor 1 circuit poor electrical connection
– Faulty Engine Control Module (ECM)