Hi, this car is kicking everyone s ass.. 92 lexus sc400. 128k. Super puff car that I am ready to drive off a cliff. had a idle surge difficulty that I researched online and did tests (per the manual) upon tps, iac and maf and cleaned the TB. After grating 2-3 interchange used IAC s, I took it to the master tech at lexus. He said it was the IAC valve. He tried my used ones.. and finally a rebuilt one. yet had issues. incite to the dealer.. this time he says, it needs a ECU. I did a lot of research on them, and found that its a common pain as soon as this car.. bought a used one.. more trouble. had the native one rebuilt by a specialist.. and that s where I am at now.. Put it in tonight and the car idles at 2k rpm. Does the TPS dependence to be re-adjusted? The master tech did all sorts of diagnostics upon every united parts (tps, maf, iac). 0-200 all times I acknowledge it get the dealer for diagnostics.. on going problems are really accumulation up. I m undecided to lie alongside the tps if he had it dialed. Any insight? Thanks in advance. Jason
Might with be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can accomplish a quick malformation locate if you unplug the meter and manage the engine without it. if the engine condition is the similar next chances are the meter or the link to it is faulty. Its also worth cleaning the MAF sensor wires, as they can acquire coated with dirt on top of period which after that offsets the reading. Use some open cleaner or brake cleaner to spray onto the wires to cut off the dirt upon no account be adjacent to the wires afterward anything as they are agreed fragile
This could be a large vacuum leak ,with the MAF related it is lonely measuring the expose that is getting next the MAF, so if the intake manifold is sucking in let breathe the ventilate to fuel ratio will be definitely out and cause the engine to stall. If MAF is disconnected the engine goes into a limp measurement and lets the engine run. bearing in mind carb cleaner spray vaporizer in the area of the hissing next the engine dealing out and bearing in mind you hear the engine stall or rev later there is the leak ,could be a bad vacuum hose bad gasket upon the manifold.