This could be an airleak after the airflow meter, any ventilate dragged in here isn t seen by the ECU and thus not compensated for and can thin the engine out and can next permit the engine to rev going on considering not desired causing harsh running. As its a mechanical deviation it tends not to position on the defect spacious and you can sometimes hear a hissing noise bearing in mind the engine running.
Might in addition to be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can pull off a quick defect find if you unplug the meter and govern the engine without it. if the engine condition is the thesame after that chances are the meter or the link to it is faulty. Its then worth cleaning the MAF sensor wires, as they can get coated past dirt over times which next offsets the reading. Use some right to use cleaner or brake cleaner to spray can onto the wires to surgically remove the dirt on no account touch the wires in the same way as anything as they are no question fragile
once I begin the car, the engine surges taking place in the middle of 1200 and 2000 rpm help and forth. I untouched the IAC and the TPS subsequently no fine-tune 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 degrade the rpm and it would support for a while. Now, the engine is permanently surging to the tapering off where I cannot drive it for danger signal of damage to the drive train. Any experienced solution?