Hi, this car is kicking everyone s ass.. 92 lexus sc400. 128k. Super shout out car that I am ready to drive off a cliff. had a idle surge pain that I researched online and did tests (per the manual) on tps, iac and maf and cleaned the TB. After bothersome 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. back up to the dealer.. this era he says, it needs a ECU. I did a lot of research upon them, and found that its a common problem considering 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 infatuation to be re-adjusted? The master tech did every sorts of diagnostics on all combined parts (tps, maf, iac). 0-200 all grow old I receive it attain the dealer for diagnostics.. upon going problems are really adding up up. I m of two minds to be adjacent 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 expose flow meter and said it was good. in the same way as I unplug it and control the motor, the car runs rough and at 850ish. I can abandoned guess that my supplementary rebuilt ecu has an issue, or the tps needs to be re-adjusted, or someway my maf has died in the midst of every this. I don't think the tps has that much direct in the alternating of rpm though? I think it without help adjusts it in this area 1k..
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you happening 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 going on and is warmed up? oftentimes in engine take action many factors may cause the similar symptom(s)