Hi, this car is kicking everyone s ass.. 92 lexus sc400. 128k. Super spread around car that I am ready to steer off a cliff. had a idle surge burden 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. back to the dealer.. this get older he says, it needs a ECU. I did a lot of research upon them, and found that its a common trouble taking into account 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 need to be re-adjusted? The master tech did every sorts of diagnostics upon every amalgamated parts (tps, maf, iac). 0-200 all time I consent it accomplish the dealer for diagnostics.. on going problems are really appendage up. I m hesitant to be next to the tps if he had it dialed. Any insight? Thanks in advance. Jason
I started the car taking place this morning, it starts occurring and runs at 1750 and within a minute or appropriately climbs on top of 2500.. It is direction mild though, just way superior than it should be. I as well as checked the throttle screw plate/return screw, with intent turned it out and nothing changed. put it encourage to exactly where it was. No vacuum leak sounds and every contacts verified. I setting fine about 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 occurring and is warmed up? oftentimes in engine play a part many factors may cause the same symptom(s)