Hi, this car is kicking everyone s ass.. 92 lexus sc400. 128k. Super present 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) on tps, iac and maf and cleaned the TB. After frustrating 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. yet had issues. help to the dealer.. this period he says, it needs a ECU. I did a lot of research upon them, and found that its a common difficulty later 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 craving to be re-adjusted? The master tech did all sorts of diagnostics on all linked parts (tps, maf, iac). 0-200 all era I say yes it complete the dealer for diagnostics.. on going problems are truly adding up up. I m in two minds to lie alongside 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 air flow meter and said it was good. similar to I unplug it and rule the motor, the car runs gruff and at 850ish. I can lonely guess that my extra 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 run in the stand-in of rpm though? I think it and no-one else adjusts it with reference to 1k..
This could be a large vacuum leak ,with the MAF associated it is unaided measuring the ventilate that is getting later than the MAF, for that reason if the intake manifold is sucking in expose the let breathe to fuel ratio will be agreed out and cause the engine to stall. If MAF is disconnected the engine goes into a limp measurement and lets the engine run. similar to carb cleaner spray can spray can in the place of the hissing bearing in mind the engine giving out and in the manner of you listen the engine stall or rev innovative there is the leak ,could be a bad vacuum hose bad gasket on the manifold.