This could be an airleak after the airflow meter, any let breathe dragged in here isn t seen by the ECU and in view of that not compensated for and can lean the engine out and can in addition to permit the engine to rev in the works when not desired causing sharp running. As its a mechanical fault it tends not to slant on the malfunction lively and you can sometimes listen a hissing noise past 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 nearly the misfortune history. It currently has a master tech endorsed 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.
later than I start the car, the engine surges going on along with 1200 and 2000 rpm incite and forth. I untouched the IAC and the TPS bearing in mind no fiddle with in symptoms. I have noticed that several Lexus SC's have this similar issue. Prior to this I would have to familiarize the idle rapidity screw to belittle the rpm and it would preserve for a while. Now, the engine is for ever and a day surging to the dwindling where I cannot steer it for dread of broken to the steer train. Any experienced solution?