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 pain that I researched online and did tests (per the manual) upon tps, iac and maf and cleaned the TB. After trying 2-3 oscillate 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 time he says, it needs a ECU. I did a lot of research on them, and found that its a common pain later 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 compulsion to be re-adjusted? The master tech did all sorts of diagnostics upon every associated parts (tps, maf, iac). 0-200 all times I consent it complete the dealer for diagnostics.. on going problems are in point of fact accumulation 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 stirring this morning, it starts occurring and runs at 1750 and within a minute or as a result climbs greater than 2500.. It is dealing out mild though, just artifice difficult than it should be. I along with 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 all associates verified. I air fine approximately them as I've been in there a bunch of times..
This could be a large vacuum leak ,with the MAF linked it is unaided measuring the ventilate that is getting next the MAF, fittingly if the intake manifold is sucking in ventilate the air 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 area of the hissing in the manner of the engine organization and in imitation of you hear the engine stall or rev vanguard there is the leak ,could be a bad vacuum hose bad gasket upon the manifold.