Hi, this car is kicking everyone s ass.. 92 lexus sc400. 128k. Super make public car that I am ready to drive 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 grating 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. still had issues. incite 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 problem 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 habit to be re-adjusted? The master tech did every sorts of diagnostics upon every connected parts (tps, maf, iac). 0-200 all grow old I acknowledge it get the dealer for diagnostics.. upon going problems are essentially adjunct up. I m unsure to be next to the tps if he had it dialed. Any insight? Thanks in advance. Jason
I did re-check them tho. The master tech did extensive tests upon the freshen flow meter and said it was good. taking into consideration I unplug it and control the motor, the car runs severe and at 850ish. I can forlorn guess that my further rebuilt ecu has an issue, or the tps needs to be re-adjusted, or somehow my maf has died in the midst of all this. I don't think the tps has that much govern in the alternative of rpm though? I think it solitary adjusts it around 1k..
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you occurring 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 happening and is warmed up? oftentimes in engine take steps many factors may cause the thesame symptom(s)