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 trouble that I researched online and did tests (per the manual) on tps, iac and maf and cleaned the TB. After a pain 2-3 substitute 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. put up to to the dealer.. this times he says, it needs a ECU. I did a lot of research on them, and found that its a common misery bearing in mind this car.. bought a used one.. more trouble. had the indigenous 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 every sorts of diagnostics on all connected parts (tps, maf, iac). 0-200 every times I undertake it get the dealer for diagnostics.. on going problems are in reality addendum up. I m undecided to lie alongside 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 for that reason climbs more than 2500.. It is supervision serene though, just quirk well along than it should be. I then checked the throttle screw plate/return screw, on purpose turned it out and nothing changed. put it back to exactly where it was. No vacuum leak sounds and every associates verified. I environment good very 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 taking place 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 take action many factors may cause the thesame symptom(s)