Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1990 Toyota Corolla Base, AutomaticFACTORY OEM SERVICE PROCEDURE
Auxiliary Air Valve System Test
- Engine must be cold to perform test. Install tachometer to engine. See ADJUSTMENTS article for tachometer attaching points.
- Start engine. Turn idle speed adjusting screw to bottom of its travel. See Fig 1. Engine RPM should drop slightly when coolant temperature is below 176°F (80°C).
- Back out idle adjusting screw. Warm engine to normal operating temperature. Turn idle speed adjusting screw to bottom of its travel. Engine should idle roughly or die as idle speed adjusting screw is seated.
- If engine RPM does not drop during step 2) or 3), check for vacuum leaks after the valve or restricted chamber in auxiliary air valve circuit. Replace valve if defective.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
Comes to youSame-day available12-month warranty
Get a Free QuoteNo obligation. See pricing before you book.