This could be an airleak after the airflow meter, any let breathe dragged in here isn t seen by the ECU and thus not compensated for and can lean the engine out and can then permit the engine to rev stirring once not desired causing sharp running. As its a mechanical irregularity it tends not to slant upon the malfunction 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 say you a tiny more virtually the pain history. It currently has a master tech qualified idle let breathe rule valve and tps installed. without distressing anything, the last (used) ecu and my original, would rule in the car without this symptom.
following I begin the car, the engine surges occurring between 1200 and 2000 rpm help and forth. I tainted the IAC and the TPS behind no bend in symptoms. I have noticed that several Lexus SC's have this same issue. Prior to this I would have to acclimatize the idle quickness screw to demean the rpm and it would support for a while. Now, the engine is constantly surging to the point where I cannot drive it for terror of broken to the drive train. Any experienced solution?