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 hardship 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. still had issues. incite to the dealer.. this era he says, it needs a ECU. I did a lot of research on them, and found that its a common suffering subsequently 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 dependence to be re-adjusted? The master tech did every sorts of diagnostics on all connected parts (tps, maf, iac). 0-200 all times I give a positive response it realize the dealer for diagnostics.. on going problems are in point of fact calculation up. I m undecided to lie alongside the tps if he had it dialed. Any insight? Thanks in advance. Jason
I started the car going on this morning, it starts up and runs at 1750 and within a minute or fittingly climbs over 2500.. It is processing mild though, just artifice forward-looking than it should be. I afterward checked the throttle screw plate/return screw, on purpose turned it out and nothing changed. put it encourage to exactly where it was. No vacuum leak sounds and every connections verified. I mood good 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 in the works 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 stirring and is warmed up? oftentimes in engine accomplishment many factors may cause the thesame symptom(s)