Jeep Cherokee

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Fuel system » Fuel injection system » Diagnosis and testing
Throttle body minimum air flow check procedure

The following test procedure has been developed to check throttle body calibrations for correct idle conditions.

The procedure should be used to diagnose the throttle body for conditions that may cause idle problems.

This procedure should be used only after normal diagnostic procedures have failed to produce results that indicate a throttle body related problem. Be sure to check for proper operation of the idle air control motor before performing this test.

A special fixed orifice tool (number 6714) (Fig. 20) must be used for the following test. This tool has a fixed internal diameter of 0.185".

Fig. 20 6714 Fixed Orifice Tool

(1) Start the engine and bring to operating temperature.

Be sure all accessories are off before performing this test.

(2) Shut off engine and remove air duct at throttle body.

(3) 2.5L 4-Cylinder Engine: Near front/top of valve cover, disconnect CCV tube at fixed orifice fitting (Fig. 21). Insert Special Tool 6714 into end of disconnected CCV tube (insert either end of tool into tube). Let tool and tube hang disconnected at side of engine.

(4) 4.0L 6-Cylinder Engine: Disconnect CCV tube (Fig. 22) at intake manifold fitting. Attach a short piece of rubber hose to special tool 6714 (insert rubber hose to either end of tool). Install rubber hose/ tool to intake manifold fitting. Let CCV tube hang disconnected at side of engine.

Fig. 21 Install Orifice Tool 2.5L 4-Cylinder Engine

1 - AIR INLET FITTING
2 - AIR FILTER COVER
3 - FIXED ORIFICE FITTING

(5) Connect DRB scan tool to 16-way data link connector. This connector is located at lower edge of instrument panel near steering column. Refer to appropriate Powertrain Diagnostic Procedures service manual for DRB operation.

(6) Start engine and allow to warm up.

(7) Using the DRB scan tool, scroll through menus as follows: select-Stand Alone DRB III, select the year 2000 Diagnostics, select-Engine, select-System Test, select-Minimum Air Flow.

(8) The DRB scan tool will count down to stabilize idle rpm and display minimum air flow idle rpm. The idle rpm should be between 500 and 900 rpm. If idle speed is outside these specifications, replace throttle body. Refer to Throttle Body Removal/Installation.

(9) Disconnect DRB scan tool from vehicle.

(10) Remove orifice tool and connect CCV tube to engine.

(11) Install air duct to throttle body.

Fig. 22 Install Orifice Tool 4.0L 6-Cylinder Engine

1 - AIR INLET FITTING
2 - FIXED ORIFICE FITTING
3 - AIR FILTER COVER

Visual inspection

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Throttle body minimum air flow check procedure