What does the A.B. valve do?

The A.B. valve is actuated by intake manifold vacuum to prevent after-burning in the exhaust system during the initial period of deceleration, when the intake mixture becomes too rich to burn in the combustion chamber and would otherwise burn in the exhaust manifold with injected air.

How do I test the air injection valve (A.I.V.) and filter?

Disconnect the air injection hose at the air injection pipe side and suck or blow on the hose to make sure air flows only toward the air injection pipe side. Also check the air injection valve for binding or damage and the filter for damage or plugging; replace if necessary.

How do I check if the A.B. valve is working?

Warm up the engine thoroughly, disconnect the hose from the air cleaner and place a finger near the outlet, then run the engine at about 3,000 rpm under no load and quickly return it to idle. If you feel a pull or suction force on your finger, the A.B. valve is functioning normally; if no suction is felt, replace it.

What should the preliminary inspection cover?

Check hoses for looseness, flattening, damage or faulty connections, and each part for proper installation. Replace if necessary.

Home/ Registry/ Nissan/ Micra/ 1990 Nissan Micra/ Photo supermotors.net/registry/media/210294

Nissan Air Injection Valve (A.I.V.) & A.B. Valve Description and Inspection

Anti-Backfire (A.B.) valve cross-section and A.I.V. inspection, Nissan EF & EC manual

‹ ›

A.B. valve cross-section and air-injection-valve inspection: intake-manifold vacuum actuates the A.B. valve to prevent deceleration afterburning in the exhaust.

AI caption June 2005 · Photo 123 of 412

This is page EF & EC-23 from a factory service manual section titled 'Exhaust Emission Control System — Air Injection Valve (A.I.V.) System.' The left column continues the system description, explaining the A.B. (after-burning) valve: it is actuated by intake manifold vacuum to prevent after-burning in the exhaust during the initial period of deceleration, when the overly rich intake mixture would otherwise burn in the exhaust manifold with injected air. A cross-section diagram (EC069) shows connections to intake manifold vacuum, intake manifold, and the air cleaner. The right column covers inspection procedures: a preliminary inspection of hoses for looseness, flattening, damage or faulty connections; an A.I.V. and filter check (disconnect the air injection hose at the pipe side, suck or blow to confirm air flows only toward the air injection pipe, then check the valve for binding/damage and the filter for plugging); and an A.B. valve functional test (warm up the engine, disconnect the hose from the air cleaner, run at about 3,000 rpm no-load, return to idle, and verify suction is felt at the outlet — if not, replace the A.B. valve). Illustrations SEC249A and SEC250A show the test procedures.

Is this accurate? Sign in to help verify it.

Frequently asked questions

What does the A.B. valve do?: The A.B. valve is actuated by intake manifold vacuum to prevent after-burning in the exhaust system during the initial period of deceleration, when the intake mixture becomes too rich to burn in the combustion chamber and would otherwise burn in the exhaust manifold with injected air.
How do I test the air injection valve (A.I.V.) and filter?: Disconnect the air injection hose at the air injection pipe side and suck or blow on the hose to make sure air flows only toward the air injection pipe side. Also check the air injection valve for binding or damage and the filter for damage or plugging; replace if necessary.
How do I check if the A.B. valve is working?: Warm up the engine thoroughly, disconnect the hose from the air cleaner and place a finger near the outlet, then run the engine at about 3,000 rpm under no load and quickly return it to idle. If you feel a pull or suction force on your finger, the A.B. valve is functioning normally; if no suction is felt, replace it.
What should the preliminary inspection cover?: Check hoses for looseness, flattening, damage or faulty connections, and each part for proper installation. Replace if necessary.