Idle Andor Rpm Hcco Concentration Check Method

NOTE: This check is used only to determine whether or not the idle and/or 2,500 rpm HC/CO complies with regulations.

1. INITIAL CONDITIONS

(a) Engine at normal operating temperature <b) Air cleaner installed

(c) All pipes and hoses of air induction system connected

(d) All accessories switched OFF

(e) All vacuum lines properly connected

HINT: All vacuum hoses for EGR systems, etc. should be properly connected.

(f) EFI system wiring connectors fully plugged

(g) Ignition timing set correctly

(h) Transmission in neutral

(i) Tachometer and HC/CO meter calibrated and at hand.

2. START ENGINE

3. RACE ENGINE AT 2,500 RPM FOR APPROX. 2 MINUTES

4. INSERT HC/CO METER TESTING PROBE INTO TAILPIPE AT LEAST 40 cm (1.3 ft)

5. CHECK HC/CO CONCENTRATION AT IDLE AND/OR 2,500 RPM

Complete the measuring within three minutes.

NOTE: When performing the 2 mode (2,500 rpm and idle) test, follow the measurement order prescribed by regulations.

If the HC/CO concentration at 2,500 rpm does not comply with regulations, try the following procedure.

Race the engine again at 2,500 rpm for approx. 1 minute, and quickly repeat steps 4 and 5 above. This may correct the problem.

Troubleshooting

If the HC/CO concentration does not comply with regulations. perform troubleshooting in the order given below.

1. Check oxygen sensor operation. (See page FI-119)

2. See the table below for possible causes, and then inspect and correct the applicable causes if necessary.

HC

CO

Symptoms

Causes

High

Normal

• Incorrect timing

• Fouled, shorted or improperly gapped plugs

• Open or crossed high-tension cords

• Cracked distributor cap

2. Incorrect valve clearance

3. Leaky EGR valve

4. Leaky intake and exhaust valves

5. Leaky cylinder

High

(Fluctuating HC reading)

1. Vacuum leak:

• Intake manifold (Air intake chamber)

• Throttle body

• Brake booster line

2. Lean mixture causing misfire

High

(Black smoke from exhaust)

1. Restricted air filter

2. Faulty EFI system:

• Faulty pressure regulator

• Clogged fuel return line

• Faulty air flow motor

• Defective water temp, sensor

• Defective air temp, sensor

• Faulty injector

• Faulty cold start injector

• Faulty throttle position sensor

EWS600

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