Ignition System - Engine Bucking/Surging
88amcjeep05
Models
1987-88 Comanche Wagoneer And Cherokee With 4.0L Engine
Subject
Engine Ignition Cross Fire
Index
DRIVEABILITY
Date
July 25, 1988
No.
18-53-88
P-2927 (C18-55)
SYMPTOM/CONDITION
Some 1987-88 Cherokee, Wagoneer and Comanche vehicles with the 4.0L engine may exhibit an engine ignition cross fire during vehicle operation. The ignition cross fire will normally occur as a harsh bucking or surging condition.
NOTE: THIS BULLETIN SUPERSEDES DISTRIBUTOR INSTALLATION PROCEDURES IN I.S. NOTES 31E, 40E, 42E (M.R. 244) AND 21E, 34E, 36E (M.R. 277).
DIAGNOSIS
Road test the vehicle with the MS 1700 Diagnostic Tester in the "State Display" test mode. Observe the engine vacuum and record the vacuum reading when the cross fire condition occurs. An engine cross fire complaint will be repeatable at the vacuum range which was previously recorded regardless of engine vehicle speed.
If a cross fire condition is diagnosed, proceed with the following repair procedure.
PARTS REQUIRED
Distributor Cap (1) PN 33004024
REPAIR PROCEDURE
1. Turn the ignition switch to the OFF position. Disconnect the battery negative terminal.
2. Remove the coil wire and spark plug wires from the distributor cap.
FIGURE 1:
3. Remove the distributor cap (A) and cut a "window" (C) into the side of the distributor cap at the #1 spark plug wire post (D). The "window" should be large enough to allow easy visual inspection of the position of the distributor rotor (E) at the #1 spark plug wire post. Reinstall the distributor cap. Figure 1
FIGURE 2:
4. Install a wrench or socket onto the vibration damper retaining bolt (F). Rotate the engine in a clockwise direction until the #1 cylinder is at top dead center. Align the timing mark (G) on the vibration damper (H) with the "0" degree mark on the front cover timing scale. The tip of the distributor rotor should be near the #1 spark plug wire post. Figure 2
FIGURE 3:
5. Disconnect the distributor electrical connection. Remove the distributor holddown clamp, holddown bolt and distributor. Remove the distributor cap and rotor.
6. Place the distributor housing upside down in a soft jaw vise. Scribe a line (I) 1/2 inch from the end of the distributor locating tab (J). Cut the distributor locating tab at the scribed line with a saw.
FIGURE 4:
7. Remove any burrs and metal filings from the distributor. Reinstall rotor.
8. If necessary, using a flat blade screwdriver, turn the oil pump gear drive shaft (B) until the slot is slightly past the 11 o'clock position. The oil pump gear drive shaft is accessible through the distributor mounting bore (N) in the engine block. Figure 4
FIGURE 5:
9. Visually align the modified locating tab area (K) of the distributor housing with the holddown clamp bolt hole (L). Figure 5
FIGURE 6:
10. Turn the rotor to the 4 o'clock position. Figure 6
11. Lower the distributor into the engine block until it seats. The rotor should now be very close to the 5 o'clock position. Figure 6
FIGURE 7:
12. Reinstall the distributor cap with the cutout "window". Rotate the distributor housing until the trailing edge of the distributor rotor tip
(E) is just departing from the #1 spark plug wire post terminal (D). Figure 7
13. Reinstall the distributor holddown clamp and bolt. Tighten the holddown bolt to 9.5-14 ft.lbs. Reinspect the position of the rotor to the #1 spark plug wire post to insure that it has not moved.
14. Install the new, distributor cap, reconnect the distributor electrical connections and the battery negative terminal.
POLICY: Reimbursable under the provisions of the warranty.
SRT/TIC INFORMATION:
OPERATION
OPERATION DESCRIPTION NUMBER TIME TIC FAILURE CODE
CO. DISTRIBUTOR ADJUST - 0106 0.6 1717
4.0L CROSS FIRE 08-15-24-90 0.6 RO-DRIVEABILITY