Hi, this car is kicking everyone s ass.. 92 lexus sc400. 128k. Super push car that I am ready to drive off a cliff. had a idle surge pain that I researched online and did tests (per the manual) on tps, iac and maf and cleaned the TB. After exasperating 2-3 alternative 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 mature he says, it needs a ECU. I did a lot of research upon them, and found that its a common trouble similar to this car.. bought a used one.. more trouble. had the original 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 habit to be re-adjusted? The master tech did every sorts of diagnostics upon every aligned parts (tps, maf, iac). 0-200 every epoch I bow to it get the dealer for diagnostics.. on going problems are truly supplement up. I m undecided to touch the tps if he had it dialed. Any insight? Thanks in advance. Jason
I started the car in the works this morning, it starts happening and runs at 1750 and within a minute or so climbs more than 2500.. It is running serene though, just pretentiousness sophisticated than it should be. I moreover checked the throttle screw plate/return screw, deliberately turned it out and nothing changed. put it assist to exactly where it was. No vacuum leak sounds and all associates verified. I tone good more or less them as I've been in there a bunch of times..
This could be a large vacuum leak ,with the MAF linked it is single-handedly measuring the expose that is getting behind the MAF, fittingly if the intake manifold is sucking in ventilate the ventilate to fuel ratio will be agreed out and cause the engine to stall. If MAF is disconnected the engine goes into a limp measurement and lets the engine run. subsequently carb cleaner spray can spray in the area of the hissing later than the engine admin and gone you listen the engine stall or rev far ahead there is the leak ,could be a bad vacuum hose bad gasket on the manifold.