Throttle - Heavy Feel
19-26Throttle Pedal Action - Heavy Feel - Revised Throttle Pedestal
MODEL 94 MY V12 DATE 4/94
ISSUE:
Throttle pedal action on XJ12 and 6.0 Liter XJS vehicles has been made lighter and more progressive through revisions to the throttle pedestal assembly and the return springs. All vehicles are built with the revised components from the following VINs:
XJ12 from VIN 687220
6.0 Liter XJS from VIN 190129
ACTION:
To address customer complaints of "heavy" throttle action on XJ12 and 6.OL XJS vehicles prior to the VINs listed above, fit revised throttle components using the following procedures:
1. Record preset radio stations and disconnect the battery. Open the hood, fit fender covers.
2. Loosen the lock nut and release the outer throttle cable from the pedestal bracket. Rotate the throttle pulley and release the inner cable from the pulley.
3. Inside the vehicle, fully depress the throttle pedal and release the cable from the pedal assembly.
4. In the engine compartment, displace the outer cable and grommet at the pedal box. Remove the throttle cable from the vehicle.
5. Remove the plastic engine cover.
6. Disconnect the throttle operating rods from the throttle pulley. Rotate the throttle pulley and disconnect the cruise control actuator rod from the throttle pulley.
7. Disconnect the idle switch multiplug and release the throttle potentiometer harness multiplug from its mounting bracket. Remove the screws from the oxygen sensor multiplug bracket and move the bracket for access. Disconnect the throttle potentiometer multiplug.
8. Remove the nuts securing the throttle pedestal assembly and remove the pedestal from the vehicle. Place the pedestal assembly on a work bench.
9. To assist in reassembly, mark the throttle potentiometer mounting plate and pedestal housing for position. Remove the throttle potentiometer from the pedestal.
10. Release the outer spring (E Fig. 1) from the cruise control bracket. Remove and discard the bracket (N Fig. 1).
11. Bend the lock tab from the throttle pedestal retaining nut and remove the nut and tab washer.
12. To assist in reassembly, note the locations of the end lugs on the outer and inner torsion springs (E and G Fig. 1). Disassemble the throttle pedestal. Discard the original throttle pulley, outer and inner torsion springs (D, E and G Fig. 1).
13. Install the thinnest shim from the shim kit (JLM 11627) onto the shaft (J Fig. 1). Insert and fully seat the shaft into the housing (M Fig. 1)
14. Rotate the shaft so that, when viewed from below, the flat on the shaft is facing the cast in lug (A Fig. 2).
15. Referring to Figure 1, assemble the components of the throttle pedestal as follows:
^ nylon washer (H)
^ revised inner torsion spring (G) (NAB 3131BA) - engage lower lug into hole in plate (P) and housing (M).
^ spring separator (F)
^ revised outer torsion spring (E) (NAB 3131AA) - engage lower lug into hole in plate (P).
^ revised throttle pulley (D) (NAB 3111AA) - engage the upper lug of the inner torsion spring into the locating hole in the pulley.
^ nylon washer (C).
^ thrust washer (B).
16. Starting with the flat on the lower end of the shaft positioned as indicated in Figure 2, rotate the throttle pulley half a turn clockwise, as viewed from above. While holding the throttle pulley against the spring tension, align and fit the throttle rod bracket (A) to the top of the shaft.
17. Fit a new tab washer (C 43231). Fit and tighten the retaining nut. DO NOT BEND THE LOCK TAB AT THIS TIME.
18. Fit the revised cruise control bracket (N) (NAB 3088AA), fit and tighten the retaining screws.
19. Tension the outer torsion spring 1 turn clockwise, as viewed from above, and position the upper lug of the spring into the cruise control bracket.
20. Lightly clamp the pedestal housing in a vise. Mount a dial indicator and measure the shaft end float in the housing, as illustrated in Figure 3.
Required end float: 0.002 - 0.010" (0.05 - 0.25 mm)
21. If there is more than .010" end float, use an alternative shim from the kit to obtain the required end float. Use the following procedure:
^ Loosen the top nut on the shaft until only one or two threads remain engaged. Hold the assembly together to prevent disengagement of the torsion springs and push the shaft downwards until the circlip and shim project from the bottom of the housing.
^ Remove the circlip and replace the thinnest shim with the appropriate alternative shim. Shim thicknesses are:
thinnest = 0.035" (0.88 mm) (EBC 8094/2)
middle = 0.042" (1.05 mm) (EBC 8094/1)
thickest = 0.050" (1.25 mm) (EBC 8094)
^ Refit the circlip, tighten the retaining nut and check end float as illustrated in Figure 3. If the required end float has been obtained, bend the lock tab against the retaining nut.
22. Align and install the throttle potentiometer, using the marks made before disassembly.
23. Refit the throttle pedestal assembly to the engine. Connect throttle potentiometer and idle switch multiplugs. Secure the oxygen sensor multiplug bracket. Connect the throttle and cruise control actuator rods.
24. Refit the engine cover.
25. Insert the revised throttle cable (XJ12 part # MMB 4620BA, XJS part # MMC 4620AA) into the pedal box. Push the inner cable as far as possible towards the throttle pedal.
26. Inside the vehicle, connect the inner cable to the throttle pedal.
27. From the engine compartment, pull on the inner cable, rotate the throttle pulley, and connect the inner cable to the pulley. Position the outer cable through the pedestal bracket. Adjust the lock nuts to obtain minimum cable free play while ensuring that the throttle pulley returns against the idle stop. Tighten the cable lock nuts.
28. Replace existing throttle return springs on the left and right side butterfly linkage arms with revised return springs (NAB 3030AB). Discard original return springs.
29. Check and adjust the throttle linkage. Refer to the XJ6/XJ12 Service Manual section 19.2-20-11.
30. Perform a complete engine set-up using JDS or PDU.
31. Remove the fender covers, close the hood.
32. Reconnect the battery, recode the radio, reset radio stations and clock.
PARTS INFORMATION:
WARRANTY INFORMATION:
Fault Code R.O. Number Time Allowance
2MEY 19.91.36 1.70 hrs. (6.OL XJS and XJ12)