I have a 1999 ls400 that recently has had the water pump timing belt and serpentine belt replaced as well as a few other small things (bearing based parts connected to those belts) the battery has had issues before and the alternator and i have completely replaced the cooling system except for the thermostat housing (radiator, lines, thermostat, fan clutch, ect) I have been having transmission issues but I don’t believe it is appart of that specific issue I need help with since the car was in park. I let the engine warm up and noticed it was idling at 1200 instead of the usual 7-800 depending on outside temperature. I have been researching online and think it could be the idle valve is faulty or dirty but I could be wrong. Car is not giving any codes except for 02sensors from the straight pipe. Any insite would be appreciated.
It's normal for cars to run rich and idle high right after you start the engine. The idle should go back down to normal after a minute or two. If it doesn't, then try removing and cleaning the idle air control valve with throttle cleaner spray. It's pretty easy and there are videos on youtube on how to do it.
Your exhaust is likely the problem. If it is straight piped, the car will idle high because it is trying to warm up the catalytic converters so they can operate as intended. I'm guessing you have no cats and have never had the car tuned, correct? If so, it is your computer freaking out because your flow is all out of whack and your air/fuel ratio is all over the place.
Straight piping a car and deleting the catalytic converters is one of the worst things you can do. Cat deletes do not improve flow or performance in anyway. If you are going to remove them (which is illegal, BTW), you need to tune the ECM for the change.
I have had countless cars in my shop because some guy decided a true exhaust system was too much money so they straight piped their car, hacked off the converters, and now they have phantom issues and no clue why. A bad idea all around.
