This could be an airleak after the airflow meter, any freshen dragged in here isn t seen by the ECU and suitably not compensated for and can lean the engine out and can afterward allow the engine to rev up taking into consideration not desired causing rasping running. As its a mechanical aberration it tends not to twist upon the malformation light and you can sometimes listen a hissing noise considering the engine running.
Thanks for your response. I just checked what you mentioned, that I hadn't already checked, except fuel pressure.Let me say you a tiny more about the misery history. It currently has a master tech recognized idle air manage valve and tps installed. without heartwarming anything, the last (used) ecu and my original, would run in the car without this symptom.
following I start the car, the engine surges stirring between 1200 and 2000 rpm help and forth. I untouched the IAC and the TPS later no correct in symptoms. I have noticed that several Lexus SC's have this thesame issue. Prior to this I would have to familiarize the idle rapidity screw to humiliate the rpm and it would retain for a while. Now, the engine is forever surging to the point where I cannot drive it for distress signal of damage to the steer train. Any experienced solution?