Hi, this car is kicking everyone s ass.. 92 lexus sc400. 128k. Super present car that I am ready to steer off a cliff. had a idle surge suffering that I researched online and did tests (per the manual) upon 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. yet had issues. support to the dealer.. this grow old he says, it needs a ECU. I did a lot of research upon them, and found that its a common burden similar to this car.. bought a used one.. more trouble. had the native 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 on every associated parts (tps, maf, iac). 0-200 all get older I take on it do the dealer for diagnostics.. on going problems are in fact surcharge up. I m hesitant to touch 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 on the freshen flow meter and said it was good. as soon as I unplug it and manage the motor, the car runs harsh and at 850ish. I can on your own guess that my other rebuilt ecu has an issue, or the tps needs to be re-adjusted, or anyhow my maf has died in the midst of all this. I don't think the tps has that much direct in the swap of rpm though? I think it unaided adjusts it approaching 1k..
This could be a large vacuum leak ,with the MAF united it is single-handedly measuring the expose that is getting similar to the MAF, as a result if the intake manifold is sucking in expose the air to fuel ratio will be definitely out and cause the engine to stall. If MAF is disconnected the engine goes into a limp measurement and lets the engine run. subsequently carb cleaner spray can spray can in the area of the hissing taking into consideration the engine government and past you hear the engine stall or rev difficult there is the leak ,could be a bad vacuum hose bad gasket upon the manifold.