Idling Problems

Hi there,

My ST185 isn't idling properly. Idle is supposed to be ~800-900 RPM, but most of the time when I let off the gas it drops to around 400RPM and bounces between 400 and 800 RPM for a while before either surging up to 1500RPM for a minute and then repeating the cycle, or, stalling out entirely. Has anyone dealt with this before and know what I should be looking at to fix it? My understanding is the idler is fully automatic and non adjustable on these cars, some arcane black magic mechanism?

Check for vacuum leaks, and also the AFM? The flapper door can get gooey, also the TPS sensor is a possibility. DO you have access to another 185 that you could swap some parts? THE TPS is adjustable so I wouldn't mess with that unless you are confident you can mark the screw locations and get it back to spec. Im sure there are some speed shops that have worked on MR2 or Alltracs around you

sounds like a vac leak to me. new to the platform, but vac leaks will cause the issues you referenced.. just dealt with this behavior on one of my cars the other day. vac leak caused odd idling behvior and roughness and eventually would stall if i didn't open up the throttle myself.. listen to the engine bay next time you start the car.. you'll probably hear the high pitch from the extra unmetered air getting sucked in. if you can't figure it out just get a vac leak test guage from harbor freight. gl