This could be an airleak after the airflow meter, any let breathe dragged in here isn t seen by the ECU and for that reason not compensated for and can thin the engine out and can as a consequence permit the engine to rev stirring in imitation of not desired causing scratchy running. As its a mechanical defect it tends not to incline on the anomaly vivacious and you can sometimes hear a hissing noise subsequent to the engine running.
Thanks for your response. I just checked what you mentioned, that I hadn't already checked, except fuel pressure.Let me tell you a tiny more more or less the pain history. It currently has a master tech ascribed idle expose rule valve and tps installed. without heartwarming anything, the last (used) ecu and my original, would rule in the car without this symptom.
like I start the car, the engine surges stirring in the middle of 1200 and 2000 rpm back and forth. I untouched the IAC and the TPS considering no regulate in symptoms. I have noticed that several Lexus SC's have this same issue. Prior to this I would have to familiarize the idle rapidity screw to subjugate the rpm and it would maintain for a while. Now, the engine is for ever and a day surging to the point where I cannot drive it for terror of broken to the steer train. Any experienced solution?