Hi, this car is kicking everyone s ass.. 92 lexus sc400. 128k. Super make public car that I am ready to steer 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 aggravating 2-3 oscillate 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. still had issues. put up to to the dealer.. this epoch he says, it needs a ECU. I did a lot of research upon them, and found that its a common hardship later 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 craving to be re-adjusted? The master tech did every sorts of diagnostics upon all united parts (tps, maf, iac). 0-200 all time I assume it do the dealer for diagnostics.. upon going problems are truly adding together up. I m hesitant to be next to the tps if he had it dialed. Any insight? Thanks in advance. Jason
Its afterward worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all repercussion in insufficient fuel visceral delivered to the engine. Might next be worth cleaning out the idle quickness run motor / valve as these get clogged stirring in the same way as carbon and some brake cleaner washed through helps release things off.
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you going on 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 going on and is warmed up? oftentimes in engine put-on many factors may cause the same symptom(s)