DIY: Auxiliary Air Control Valve


Feb 27

Happy belated New Year! This is a DIY idea for those of you that have experience issues with Idle Air Control Valve (IACV) acting up or just interfering with tuning altogether. On some newer EMS systems, it is possible to control IACV for tuning purposes but in this DIY, I’ll demonstrate another way to do it. Typical challenges with missing IACV are the cold morning starts that require light foot on the gas for 15-20 seconds to keep the throttle plate open enough to get the engine going. In the winter, it becomes even more tedious because if you let off too early with the throttle together with fuel enrichment – you could potentially flood it if you stall it. Then you must pop the fuel pump fuse and then crank it. I’ve only had it happen once but it’s not fun.

So whining aside :) let’s come up with a solution that keeps iacv out for tuning advantage and also lets us start the car without mickey-mousing with the gas pedal…

Below is the diagram of the idea I started with. It is based around the vacuum solenoids I took off the 2 corolla gt-s’es I took apart. Tested the vacuum solenoid – held up to over 20 psi without issues – fits the bill.

Auxiliary Idle Control Valve

And here is the actual pieces I’ve started to work on already…

Auxiliary AIr Control System

Please stay tuned for updates :)