Hi, this car is kicking everyone s ass.. 92 lexus sc400. 128k. Super publicize car that I am ready to drive off a cliff. had a idle surge misery that I researched online and did tests (per the manual) upon tps, iac and maf and cleaned the TB. After maddening 2-3 alternating 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. nevertheless had issues. encourage to the dealer.. this grow old he says, it needs a ECU. I did a lot of research upon them, and found that its a common problem once 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 obsession to be re-adjusted? The master tech did all sorts of diagnostics on every connected parts (tps, maf, iac). 0-200 every grow old I say yes it accomplish the dealer for diagnostics.. on going problems are really toting up up. I m undecided to touch the tps if he had it dialed. Any insight? Thanks in advance. Jason
Its as well as worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a under the weather pump will all consequences in insufficient fuel instinctive delivered to the engine. Might then be worth cleaning out the idle speed direct motor / valve as these acquire clogged in the works as soon as carbon and some brake cleaner washed through helps free things off.
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you in the works to date upon every maintenance; spark plugs fuel filter pcv vlave etc? have you performed a visual inspection and listened to engine as it warms in the works and is warmed up? oftentimes in engine law many factors may cause the similar symptom(s)