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Full-throttle Enrichment (engine codes HT, RD, and PL only)

The full-throttle enrichment function operates only when the engine is warm, when engine speed is above 4000 rpm (above 2500 rpm on 16-valve engines), and when the throttle is fully open. The full-throttle switch supplies a signal to the control unit when the throttle is fully open.

Fig. 6-36. Location of coolant temperature sensor. Left: bottom of cylinder head coolant outlet on all except 16-valve engines. Right: left side of cylinder head on 16-valve engines.

To check full-throttle enrichment, disconnect the harness connector from the coolant temperature sensor and, using a jumper wire, bridge the connector terminals. The sensor is shown earlier in Fig. 6-36. Start the engine. With the engine speed raised to above 4000 rpm (above 2500 rpm on 16-valve engines), actuate the full-throttle switch on top of the throttle valve by hand, as shown in Fig. 6-41. The differential pressure regulator current should increase to approximately 14 mA (approximately 16 mA on 16-valve engines).

Fig. 6-41. Small screwdriver being used to operate full-throttle switch on throttle valve and test full-throttle enrichment.

If the differential pressure regulator current reads excessively high, recheck the installation of the jumper wire at the temperature sensor connector. If the current does not increase when the full-throttle switch is closed, check for a faulty full throttle switch or a faulty rpm signal from the ignition control unit as described below under Control Unit Inputs.

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