Check EGR system for correct operation.
Check engine coolant temperature sensor operation.
Check for cracks and poor connections at throttle body.
Check for distortion and cracks in fuel injector plastic connecting flanges.
Check for poor quality fuel, fuel with high alcohol content or contaminated fuel.
Check throttle position sensor operation.
Ensure air intake system is unrestricted.
Ensure fuel system pressure is correct.
Check crankcase ventilation system
Remove air intake elbow. Remove intake elbow to throttle hose. Using a feeler gauge, measure clearance between butterfly valve (throttle plate) and throttle body. Clearance should be.038-.064" (.97-1.63 mm).
If necessary, adjust butterfly valve gap by loosening throttle cable lock at manifold bracket. Loosen throttle stop lock nut. Adjust throttle stop screw to obtain a gap of.002" (0.05 mm) between butterfly valve and each side of housing. Tighten throttle stop lock nut.
Seal threads of stop screw and lock nut with paint or RTV sealant. Recheck throttle plate clearance. Check throttle linkage adjustment. See THROTTLE LINKAGE.
Install and align Full Throttle Setting Adjuster (JD131) to throttle stop plate. Ensure pointer aligns with "I" (idle mark) on throttle linkage. See Fig. 7.
Loosen full throttle stop lock nut. Fully open throttle and adjust full throttle adjustment screw to align pointer with "M" mark on throttle linkage. Release throttle linkage and tighten full throttle stop lock nut.
Remove full throttle setting adjuster. Check kickdown switch adjustment. See KICKDOWN SWITCH. Check idle speed. Refer to IDLE SPEED & MIXTURE.
Locate throttle potentiometer harness connector. Using a digital volt-ohmmeter, backprobe terminal No. 5 (Green/Blue wire) at throttle potentiometer connector.
Turn ignition on. With accelerator pedal released (idle position), voltmeter reading should be.58-.62 volt. With accelerator pedal fully depressed (kickdown position), voltmeter reading should be 4.4-4.6 volts.
If necessary, set pedal to 90 percent of its travel and adjust pedal so voltmeter reading is 3.9-4.2 volts. This position is the kickdown point.
With accelerator pedal held at kickdown point, adjust kickdown switch to lightly contact the underside of accelerator pedal (using a piece of paper). When paper can be withdrawn with a slight resistance, the kickdown switch setting is correct. Road test vehicle to double check kickdown switch setting.
THROTTLE IDLE SWITCH
Remove engine cover. Disconnect throttle idle switch connector. See Fig. 8. Using an ohmmeter check for continuity between idle switch terminals. With throttle closed, continuity should exist.
With throttle open, continuity should not exist. If continuity is not as specified, loosen switch mounting screws and adjust switch position so continuity is as specified. Tighten mounting screws and recheck switch continuity.
Tuesday, March 23rd, 2010 AT 2:00 PM