Hello,
I just bought a SC300 with a 5 spd. It was idling high when I bought it. It has a cold air induction with the mass air sensor mounted just above the filter, then a straight piece and then a bend into the throttle body. I have searched the forum for some ideas. I found one that suggested using some fuel injection cleaner. I tried that. I cleaned the throttle body and then ran a bottle of cleaner through the tank. No change. I unhooked the battery for a few minutes to reset the ECU. The next time that I tried to start it, it tried to idle at 800 for a few seconds and then acted confused for an instant and went back up to 1250 rpm. Does anyine have any ideas for me?
Thanks,
Jeff Moore

 

Are you letting it idle with the engine warm? The engine by default when cold will idle higher, and as the temperature rises it will fall to 800. Just an idea, you never can be sure as a third party as to exactly what's happening. If not that, then I'm clueless.

 

Hello,
Yes it idles high even when warmed up. Something that I forgot to mention is that when I gas it and then let off when it is sitting at idle, as the rpm's drop they will drop so far down that the car almost dies. Then the rpm's jump up again until it sits at 1250 again. Also, the check engine light is not on. I assume that means that it thinks that it is getting good info from all of the sensors.
Jeff

 

Check for some vacuum leaks. Pull out a can of carb cleaner and do some shooting around vacuum hoses and gasket areas. Just be sure not to start your car on fire.