Throttle Valve (TV) Control Linkage System (FI)
ADJUSTMENTSThrottle Valve (TV) Control Linkage System
5.8L Carbureted Engines Only Service Adlustment Procedure
The Throttle Valve (TV) Control Linkage System consists ot the linkage lever on the carburetor, the transmission control rod assembly, and the external TV control lever on the transmission.
The linkage lever follows the motion of the carburetor throttle lever and has an adjustment screw for limited linkage adjustment capability. The TV control rod transmits motion between the linkage lever on the carburetor and the TV control lever on the transmission. It is adjusted to proper length during initial assembly. The external TV control lever actuates the internal TV control mechanism which regulates the TV control pressure. The external TV control lever motion is controlled by stops internal to the transmission at idle and wide-open throttle (WOT).
The TV control linkage is set to its proper length during initial assembly using the sliding trunnion block at the transmission end of the TV rontrol rod assembly. Under normal circumstances it should not be necessary to alter this adjustment. Any required adjustment of the TV control linkage can normally be acomplished using the adjustment screw on the linkage lever at the carburetor. Major linkage adjustment (sliding trunnion on rod) may only be required after maintenance invilving the removal and / or replacement of the carburetor, TV control rod assembly, or the transmission. Minor linkage adjustment (adjustment screw on linkage lever) may be required after installing a new main control assembly, or after idle speed adjustments greater than 50 rpm and to correct omptaints of poor transmission shift quality as outlined in following parts.
Minimum Idle Stop
When the linkage is correctly adjusted, the TV control lever on the transmission will be at its internal idle stop position (lever up as far as it will travel) when the carburetor throttle lever is at its minimum idle stop. There will be a light contact force between the throttle lever and end of the linkage lever adjustment screw. Due to flexibility in the linkage system, the linkage lever adjustment screw would have to be backed-out approximately three turns before a gap between the screw and throttle lever could be detected.
At wide-open throttle (WOT), the TV control lever on the transmission may or may not be at its wide-open stop. The wide-open throttle position must not be used as the reference point in adjusting linkage.
Linkage Adjustment-General Instructions
Before any engine TV linkage adjustment can be done, the throttle lever at the carburetor (or throttle body) must be positioned at its minimum idle stop.
Without DC Motor Idle Speed Control (ISC)
5.8L Carbureted Engine
Check/adjust the engine curb idle speed to specification. Refer to the Engine/Emissions Diagnosis manual tor procedures to adjust throttle solenoid applications. Make sure the curb idle speed is set to specification with and without the throttle solenoid positioner (antidieseling solenoid) energized, if so equipped.
2. Shut engine off. Remove air cleaner.
3. De-cam the fast idle cam on the carburetor so that the throttle lever is against the idle stop or throttle solenoid positioner stop.
Linkage Adjustment at Carburetor
The TV control linkage may be adjusted at the carburetor using the following procedure:
1. Set carburetor at minimum idle stop as described in Linkage Adjustment-General Instructions. Place shift lever in NEUTRAL and set parking brake.
Caution: The transmission selector lever must be in NEUTRAL.
2. Back-out (CCW) linkage lever adjusting screw all the way (screw end is flush with lever face).
3. Turn in (CW) adjusting screw until a thin shim of 127mm (0.005 inch) maximum, or piece of writing paper fits snug between end of screw and throttle lever. To eliminate effect of friction, push linkage lever forward (tending to close gap) and release before checking clearance between end of screw and throttle lever.
Do not apply any load on levers with tools or hands while checking gap.
4. Turn in (CW) adjusting screw an additional three turns. (Three turns are preferred. One turn minimum is permissible if screw travel is limited).
5. If it is not possible to turn in adjusting screw at least one additional turn or if there was insufficient screw adjusting capacity to obtain an initial gap in Step 2, refer to Linkage Adjustment at Transmission.
Idle Speed Adjustment
Whenever it is required to adjust idle speed by more than 50 rpm, the adjustment screw on the linkage lever at the carburetor should also be readjusted as shown:
1. Idle Speed Change
a.50 rpm or more decrease
b.Less than 50 rpm
c.50 rpm or more increase
2. Linkage Adjustment at Carburetor
a.Check TV lever adjustment at carburetor
b.No change required
c.Check TV lever adjustment at carburetor
After making any idle speed adjustments, always verify that the linkage lever and throttle lever are in contact with the throttle lever at its idle stop (or throttle solenoid positioner) and the shift lever in NEUTRAL. If this is not the case, refer to A and C in Shift Trouble Diagnosis.
Rod Linkage Adjustment at Transmission
The linkage lever adjustment screw has limited adjustment capability. If it is not possible to adjust the TV linkage using this screw, the length of the TV control rod assembly must be readjusted using the following procedure. This procedure must also be followed whenever a new TV control rod assembly is installed.
This procedure requires placing the vehicle on a hoist to give access to the linkage components at the transmission TV control lever.
1. Set carburetor at its minimum Idle stop as described in Linkage Adjustment-Genera Instructions. Place shift lever n NEUTRAL and set parking brake. Turn engine off
NOTE: Transmission selector must be in NEUTRAL.
2. Set the linkage lever adjustment screw at approximently mid-range.
3. If a new TV control rod assembly is being installed, connect the rod to the linkage lever at the carburetor.
Caution: The following steps involve working in close proximity to the exhaust system. Allow the exhaust system to cool before proceeding.
4. Raise vehicle on a hoist. Refer to the Pre-Delivery manual, Section 50-04.
5. Loosen the bolt on the sliding trunnion block on the TV control rod assembly. Remove any corrosion from the control rod and free-up the trunnion block so that it slides freely on the control rod.
6. Push up on the lower end of the control rod to ensure that the linkage lever at carburetor is firmly against the throttle lever. Release force on rod. Rod must stay up.
7. Push the TV control lever on the transmission up against its internal stop with a firm force, approximately 22 N (5 lbs). Tighten the bolt on the trunnion block. Do not relax force on ever until bolt is tightened
8. Lower the vehicle and verify that the throttle lever is still against the minimum idle stop or throttle solenoid positioner stop. If not, repeat Steps 2 through 8.
Linkage Adjustment Using TV Control Pressure
NOTE: This procedure requires the use of TV Pressure Gauge with Hose (0-60 psi) T86L-70002-A or equivalent. The results of the adjustment procedure depends on the accuracy of the pressure gauge.
A pressure gauge should be checked periodically (approximately once every six months) or when the following occurs:
1. The needle will not return to 0 kPa (0 psi) under no pressure.
2. The needle goes past 0 kPa (0 psi) (negative side) under no pressure.
3. Bumping or dropping a pressure gauge.
The following procedure may be used to check and/ or adjust the throttle valve (TV) control linkage using the TV control pressure.
1. Check/adjust the engine curb idle speed to specification required. Refer to the Enginel Emissions - manual for appropriate procedure. Ensure the curb idle speed is set to specification with and without the throttle solenoid positioner (anti-diesel solenoid) energized, if so equipped.
2. Attach Pressure Gauge (0-60 psi) with Hose T86L-70002-A and Adapter Fitting 080L-77001-A or equivalent, to the TV port on the transmission.
NOTE: If the service tool is not available, in order to avoid the exhaust system, obtain the following material and assemble as shown:
- One 1/8-inch NPT female Hansen fitting
- One 1/8-inch NPT male Hansen fitting
- One 1/4-inch NPT 90 degree elbow connector
- One One high-pressure hose fitting
The pressure gauge should have 2.4m (8 feet) of flexible hose to make the gauge accessible while operating the engine.
3. Obtain Rod TV Control Pressure Gauge Block D84P-70332-A or equivalent, or fabricate a block lOmm I 0.l7mm (0.397 1 0.007 inch) thick. The following drill bit shanks may also be used in order of preference: Letter X (.397 inch), lOmm (.3937 inch) or 25/64 (.3906 inch).
4. Operate the engine until normal operating temperature Is reached and the throttle ever off fast idle. The transmission fluid temperature should be approximately 38-72 C(150F). Do not make pressure check if transmission fluid is cold or too hot to touch
5. Set parking brake, place shift selector in NEUTRAL, remove air cleaner and shut off air conditioner. If equipped with a vacuum operated throttle modulator, disconnect and plug the vacuum line to this unit. If equipped with a throttle solenoid positioner or an idle speed control, do not disconnect either of these components.
NOTE: The following pressure check must be made with the engine idling at normal curb idle in NEUTRAL, parking brake set and with no accessory load on engine Do not make pressure check in PARK.
6. With engine idling in NEUTRAL, insert gauge block or drill shank between the carburetor throttle lever and adjust screw on the transmission linkage lever. The TV pressure should be between 207 and 276 kPa (30 and 40 psi). For best transmission function, use the adjusting screw to set the pressure as close as possible to 227 kPa (33 psi). Since the TV pressure goes up approximately 14 kPa (2 psi) when the shift lever is moved from NEUTRAL to a forward gear (� or D), this will result in a TV pressure setting near the desirable 241 kPa (35 psi) in forward gear. Do not attempt to set TV pressure with the transmission in gear. Turning the screw in will raise the pressure 10.3 kPa (1.5 psi) per turn. Backing-out the screw will lower the pressure. If equipped with idle speed control, some 'hunting" may occur and an-average pressure reading will have to be determined. If the adjusting screw does not have enough adjustment range to bring TV pressure within specification, adjust rod at the transmission.
7. Remove gauge block, allowing TV lever to return to idle. With engine still idling in NEUTRAL, TV pressure must be less than 34 kPa (5 psi). If not, back-out adjusting screw until TV pressure is less than 34 kPa (5 psi). Install gauge block and check that TV pressure is not below 207 kPa (30 psi).
Throttle Valve (TV) Control Cable System
Self-Locking (Wire Core)
5.OL HO and SEFI Engines
The throttle valve (TV) control cable system consists of a cable attaching grommet on the throttle body throttle lever, the TV control cable Cassembly, the external TV control lever on the transmission, and the cable mounting brackets at the throttle body and transmission.
As the throttle is moved from idle to wide-open throttle (WOT), the TV control cable pulls the transmission TV control lever from idle to WOT. Return of the cable and transmission lever toward idle is accomplished by the return spring on the transmission end of the cable assembly. This spring and the end of the cable assembly is protected by a flexible rubber boot. The transmission external TV control lever actuates the Internal TV control mechanism which regulates the TV control pressure. The travel of this lever is controlled by stops internal to the transmission.
The TV control cable is set and locked to its proper length during initial assembly when the grooved pin on the upper end of the cable assembly is inserted in the grommet on the throttle body lever. To release the cable locking mechanism, it is necessary to pry the grooved pin out of the grommet and push out the white locking pin. The take-up spring at the end of the cable assembly tensions the cable and takes up the slack in the system. When the grooved pin is reinserted in the grommet, the white locking tab is pushed in, automatically locking the cable to its correct length. When the cable is locked, the take up spring plays no part in the operation of the system.
Under normal circumstances, it should not be necessary to alter or readjust the initial setting of the TV control cable. Situations requiring readjustment of the TV control cable include maintenance involving the removal and/or replacement of the throttle body, transmission, TV cable assembly or installing a new main control assembly. Readjustment of the TV control cable would also be i.'ecessary to correct cbmplaints of poot transmission shitt quallity that would have been caused by a misadjustment of the TV control cable.
When the TV control cable is prperly set, the transmission Tv control lever will be at its internal idle stop (lever to rear as far as it will travel) when the throttle lever is at its idle stop.
Idle Speed Affect on TV Control Cable
The 5.0L and 5.OL HO (302 CID) SEFI engine uses an Air Bypass (ISC) that does not affect throttle position. Therefore, idle automatic setting does not affect TV cable adjustment.
TV Cable Linkage Adjustment Self-Locking (Core Wire Adjustment)
1. Remove air cleaner cover and inlet tube from throttle body inlet to access throttle lever and cable assembly.
2. Using a wide~blade screwdriver, pry grooved pin on cable assembly out of grommet on throttle body lever.
3. Using a small screwdriver, push out white locking tab.
4. Check to ensureplastic block with pin and tab slides freely on notched rod. If it does not slide freely, the white tab may not be pushed out far enough.
5. While holding throttle lever firmly against its idle stop, push grooved pin into grommet on throttle lever as far as it will go.
NOTE: While pushing pin into grdmmet, make sure you do not move throttle lever away from idle stop.
6. Install air cleaner cover and airinlet tube.
Linkage Adjustment Using Throttle Valve TV Control Pressure
Core Wire Adjustment
NOTE: This procedure requires the use of TV Pressure Gauge with Hose (0-60 psi) T86L-70002-A or equivalent. The results of the adjustment procedure depends on the accuracy of the pressure gauge.
A pressure gauge should be checked periodically (approximately once a year) or when the following occurs:
1. The needle will not return to 0 kPa (0 psi) under no pressure.
2. The needle goes past 0 kPa (0 psi) (negative side) under no pressure.
3. Bumping or dropping a pressure gauge.
Adjustment and/or Check
1. Attach TV Pressure Gauge with Hose (0-60 psi) T86L-70002-A or equivalent, to the TV port on the transmission.
NOTE: If service tool is not available, in order to avoid the exhaust system, obtain the following material and assemble as shown:
^ One 1/8-inch NPT female Hansen fitting
^ One 1/8-inch NPT male Hansen fitting
^ One 1/4-inch NPT 90 degree elbow connector
^ One high-pressure hose fitting
The pressure gauge should have 2.4m (8 feet) of flexible hose to make the gauge accessible while operating the engine.
2. Remove the air cleaner cover and inlet tube from the throttle body inlet for easier access to throttle lever.
3. Insert tapered end of the tool between the crimped slug on the end of cable and plastic notched rod, also on end of cable assembly. Push in Cable TV Gauge Tool T86L-70332-A, or equivalent forcing the crimped slug away from the plastic rod. Ensure gauge block is pushed in as far as it will go.
WARNING: THIS PROCEDURE REOUIRES WORKING IN CLOSE PROXIMITY TO THE EGR SPACER ASSEMBLY WHICH MAY BE HOT.
4. Operate engine until normal operating temperature is reached. The transmission fluid temperature should be approximately 38-72°C (100-1 500 F). Do not make pressure check if transmission fluid is cold or too hot to touch.
5. Set parking brake and place shift selector in NEUTRAL. With gauge tool in place and engine idling in NEUTRAL, the TV pressure should be between 207 and 276 kPa (30 and 40 psi).
NOTE:Do not check or set TV pressure in PARK.
6. If TV pressure meets specification in Step 5, remove gauge tool allowing cable to returnto its normal idle position. With engine still idling in NEUTRAL, TV pressure must be at or near zero (less than 34 kPa (5 psi)).
7. If TV pressure does not meet specification in either or both Steps 5 and 6, remove gauge tool and readjust cable as outlined under TV Cable Adjustment-Self-Locking System.
8. Check TV Pressure again. Refer to Steps 3 through 6.
9. If TV pressure still does not meet specification, it will be necessary to modify adjustment as follows.
10. Remove gauge tool and pry grooved pin out of grommet on throttle lever.
11. Mark or me~sure location of plastic block on notched rod.
12. Push out Iockin9 tab.
13. Using mark or measurement on plastic block as reference, move plastic block towards throttle mounting bracket to raise TV pressure, or move it away from bracket to lower TV pressure. Push in while locking tab to lock block in position.
14. Insert grooved pin into grommet.
15. Check TV pressure. Refer to Steps 3 through 6.
16. Fepeat Steps 10 through 14, if necessary.
NOTE: For best ansrnisscn function the Ti pressure should be set as close as possible to 227 kPa (33 psi) in NEUTRAL with gauge tool installed. Since the TV pressure goes up approximately 14 kPa (2 psi) when the shift lever is moved from NEUTRAL to a forward gear (D), this will result in a TV pressure setting near the desirable 241 kPa (35 psi) in forward gear. Do not attempt to check TV pressure with the transmission in gear. When the gauge tool is removed, the TV pressure should drop to less than 34 kPa (5 psi). If the TV pressure does not drop to less than 34 kPa (5 psi), reset the TV pressure to a value less than 227 kPa (33 psi) with gauge tool installed but no less than 207 kPa (30 psi). Verify that the TV pressure is less than 34 kPa (5 psi) with gauge tool removed.