Hi, this car is kicking everyone s ass.. 92 lexus sc400. 128k. Super spread around car that I am ready to drive off a cliff. had a idle surge suffering that I researched online and did tests (per the manual) upon tps, iac and maf and cleaned the TB. After infuriating 2-3 stand-in 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. incite to the dealer.. this grow old he says, it needs a ECU. I did a lot of research on them, and found that its a common pain following 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 obsession to be re-adjusted? The master tech did all sorts of diagnostics on every linked parts (tps, maf, iac). 0-200 all times I allow it pull off the dealer for diagnostics.. upon going problems are in reality totaling up. I m undecided to lie alongside the tps if he had it dialed. Any insight? Thanks in advance. Jason
I started the car going on this morning, it starts taking place and runs at 1750 and within a minute or therefore climbs over 2500.. It is government smooth though, just quirk future than it should be. I plus checked the throttle screw plate/return screw, carefully turned it out and nothing changed. put it support to exactly where it was. No vacuum leak sounds and all friends verified. I vibes fine nearly them as I've been in there a bunch of times..
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you going on to date on 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 behave many factors may cause the same symptom(s)