Jump to content

custom intake manifold / IDLE VALVE CONTROL


Recommended Posts

Im sure I wrote a post on this but it seems to be missing...



Anyway, as Colin has said above it depends on what throttle body you are using ie stock or aftermarket. The stock throttle body has water lines running through a waxostat and dependent on the temperature of the water it allows air to bypass the throttle butterfly which raises idle when its cold. This slowly closes as the water heats up and then when hot your idle is set by the idle screw.



Most aftermarket throttle bodies don't have this system and instead idle is controlled electronically via an ecu. The factory starlet ecu doesnt really have this control though due to what ive said above although there is the aircon idle up solenoid and that you can use via a switch or small temperature controller to open or close based on temp - it wont be a smooth transition from cold high to warm low idle but rather a step as the solenoid closes when it reaches the desired temp.



If you have a half decent aftermarket ecu then you should be able to setup a PWM controlled idle control solenoid that bypasses air around the throttle butterfly just like the stock setup but controlled via the ecu. The three wire units are the best and can be used to very accurately control the idle. I use the bosch 3 wire units in a lot of my customers builds and they work very very well. The factory solenoids don't like PWM control and the coils burn out after a time so I wouldnt recommend using them for anything but open or closed use.



Another option although quite crude and touchy is to not use any idle speed solenoid and just set the hot idle at say 1000rpm and just rely on cold start enrichment to keep the engine going when its cold but that often results in a very low idle when its cold that slowly increases as the engine gets warmer and the enrichment ramps out.


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...