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Home >> Jeep >> 2000 >> Cherokee Classic, 2D Pickup >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Diagnostic Procedures >> Preliminary Inspection & Adjustments >> Checking Engine Mechanical Systems
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Checking Engine Mechanical Systems

NOTE: If Powertrain Control Module (PCM) is replaced, PCM must be reprogrammed. See PROGRAMMING . After each repair procedure has been completed, reconnect all components.
  1. Only perform this procedure if instructed to do so. This procedure assumes that all engine electrical control systems have been determined to be operating as designed and are not causing a driveability problem. The following non-monitored components or systems could cause a driveability problem. Check the following for possible causes of a driveability problem:
    • Ensure engine vacuum is at least 13 in. Hg with transmission in Neutral.
    • Check valve timing. See appropriate article in ENGINES.
    • Check engine compression. See MECHANICAL INSPECTION .
    • Check for exhaust system restrictions.
    • On 2.5L and 4.0L, check closed crankcase ventilation system for proper operation. On 4.7L, check positive crankcase ventilation system for proper operation. On all models, see EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article.
    • Check torque converter stall speed (A/T). See appropriate OVERHAUL article in AUTOMATIC TRANSMISSIONS.
    • Check power brake booster for internal vacuum leak.
    • Check for fuel contamination.
    • Ensure injector control wire is connected to correct fuel injector and injector is not plugged or restricted.
    • On 4.7L, remove CKP sensor. Inspect tone wheel/flexplate for damage. Check slotted areas on tone wheel/flexplate for damage or any foreign debris. Ensure tone wheel/flexplate turns when engine is cranked. Repair or replace tone wheel/flexplate as necessary. If tone wheel/flexplate is okay, go to step  3.
    • On 2.5L and 4.0L, ensure ignition is off. Remove crankshaft position sensor. CKP sensor is mounted to left side of transmission bellhousing. Inspect notches on flywheel/drive plate for damage or debris. On 2.5L, flywheel/drive plate contains 2 sets of notches which contain 4 slots each on outer edge of flywheel/drive plate. On 4.0L, flywheel/drive plate contains 3 sets notches which contain 4 slots in each set. On all models, check slotted areas for damage or any foreign debris. If slotted areas on flywheel/drive plate are damaged or debris exists, repair or replace flywheel/drive plate as necessary. If no problems are indicated, go to next step (2.5L) or go to step  3 (4.0L).
    2. NOTE: On 2.5L, setting distributor position does not adjust ignition timing. Ignition timing is controlled by the PCM. Distributor position determines fuel synchronization only.
  2. On 2.5L, ensure distributor is set in the proper position. Connect scan tool to data link connector. Select SET SYNC from scan tool menu. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Observe scan tool display. If scan tool does not display IN RANGE, loosen distributor hold-down clamp bolt and rotate distributor until reading is as close to zero degrees as possible, and IN RANGE message is displayed. Tighten hold-down clamp bolt to 17 ft. lbs. (23 N.m). Go to next step.
  3. On all models, if you came to this test from an oxygen sensor diagnostic test in a SELF-DIAGNOSTICS article, and rich or lean condition is still not corrected after checking all the items listed above, replace PCM. Perform TEST VER-2  under VERIFICATION TESTS.
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