Idling At 1250

[jmooremtb]

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. It idles high even when warmed up. 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. Does anyone have any ideas for me?

Thanks,

Jeff Moore

[Jono]

Did you ever find out what the problem was? My '92 SC400 is doing pretty much the same thing now. The idling is always jumping up from about 700rpm to 1200rpm. It almost never drops below 700rpm. Today it actually shot up to 3,000rpm and dropped back to regular idle after a few seconds. Based on my search results in this forum, I had the throttle body cleaned out, all the hoses connected to the MAF, intake, etc are intact, and no engine codes are showing up. Not sure if the throttle position sensor needs to be replaced but I thought it would show a code if it was needed. Any help assistance/suggestions be great.