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.
Jet Air System: Operation
Air flows to jet valve through 2 intake openings near carburetor throttle valve (below fuel injection mixer on Starion Turbo), a passage in intake manifold and a passage in cylinder head. The intake stroke pulls air into combustion chamber through intake valve port and jet valve opening. When throttle valve opening is small, a large pressure difference is produced between jet valve opening and jet intake opening as piston goes down.
This causes jet air to flow into the combustion chamber at a much higher speed than it does at large throttle openings. Because the jet valve opening points directly at spark plug, the air stream scavenges gases accumulated in that area. It also produces a swirling action in the combustion chamber, resulting in a longer burn period after ignition.
On Cordia and Tredia models, the thermo valve opens the jet air control valve when engine coolant temperature is at predetermined value. At temperatures below and above the predetermined value, the jet air control valve remains closed (no jet air is admitted to cylinder).
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.