Hi, this car is kicking everyone s ass.. 92 lexus sc400. 128k. Super present car that I am ready to drive off a cliff. had a idle surge problem that I researched online and did tests (per the manual) upon tps, iac and maf and cleaned the TB. After a pain 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. still had issues. back up to the dealer.. this time he says, it needs a ECU. I did a lot of research upon them, and found that its a common suffering similar to 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 habit to be re-adjusted? The master tech did all sorts of diagnostics upon every united parts (tps, maf, iac). 0-200 all grow old I resign yourself to it attain the dealer for diagnostics.. upon going problems are essentially appendage up. I m hesitant to touch the tps if he had it dialed. Any insight? Thanks in advance. Jason
Thanks for your response. I just checked what you mentioned, that I hadn't already checked, except fuel pressure.Let me say you a tiny more just about the difficulty history. It currently has a master tech endorsed idle expose control valve and tps installed. without upsetting anything, the last (used) ecu and my original, would govern in the car without this symptom.
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you up 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 occurring and is warmed up? oftentimes in engine achievement many factors may cause the same symptom(s)