1999 4runner 3.4L, Automatic , 150k miles
Recently my 4runner has had intermittent power loss. This problem only happens after the vehicle has been ran for 10 or more minutes and shut off and restarted. To say that another way, the power loss problem never happens on initital start up. I will be at a stop and go to accelerate and the vehicle will sputter out, then eventually regain full power ( maybe 10-60 seconds of power loss) . the only other sympton is after its warmed up occasionaly it will have a rough idle ( idle fluxuates, and at times sounds as if the engine will stall ) .
Check engine light is on, with code P0171 (system lean in bank 1).
Here is what I have done , checked for a vaccum leak, cleaned injectors, cleaned MAF, replaced fuel filter, cleaned air filter, replaced TPS, fixed small exhaust leak.
I have had no luck, I still have intermittent power loss when the vehicle is warm. when this happens you can press the gas to the floor and hear the airbox opening .
The upstream 02 sensor has been replaced, approx 50k ago. the downstream 02 sensor has not been replaced.
My thoughts are maybe the MAF needs replaced, or possibly 02 sensor issue.
I should also mention more recently fuel milage has been cut in half. from 19-20 mpg to 10 or less.
Any help would be appreciated. thank you
Recently my 4runner has had intermittent power loss. This problem only happens after the vehicle has been ran for 10 or more minutes and shut off and restarted. To say that another way, the power loss problem never happens on initital start up. I will be at a stop and go to accelerate and the vehicle will sputter out, then eventually regain full power ( maybe 10-60 seconds of power loss) . the only other sympton is after its warmed up occasionaly it will have a rough idle ( idle fluxuates, and at times sounds as if the engine will stall ) .
Check engine light is on, with code P0171 (system lean in bank 1).
Here is what I have done , checked for a vaccum leak, cleaned injectors, cleaned MAF, replaced fuel filter, cleaned air filter, replaced TPS, fixed small exhaust leak.
I have had no luck, I still have intermittent power loss when the vehicle is warm. when this happens you can press the gas to the floor and hear the airbox opening .
The upstream 02 sensor has been replaced, approx 50k ago. the downstream 02 sensor has not been replaced.
My thoughts are maybe the MAF needs replaced, or possibly 02 sensor issue.
I should also mention more recently fuel milage has been cut in half. from 19-20 mpg to 10 or less.
Any help would be appreciated. thank you
