1993 Jeep Cherokee

1993 ENGINE PERFORMANCE

Chrysler Corp. On-Vehicle Adjustments

Jeep; Cherokee, Grand Cherokee, Grand Wagoneer, Wrangler

ENGINE MECHANICAL

Before performing any on-vehicle adjustments to fuel or ignition systems, ensure engine mechanical condition is okay.

VALVE CLEARANCE

All models are equipped with hydraulic valve lifters. No adjustments are required.

IGNITION TIMING

All Jeep vehicles are equipped with Powertrain Control Module (PCM) computerized ignition system. PCM controls ignition timing. Adjustment is not required or possible.

IDLE SPEED & MIXTURE

All Jeep vehicles are equipped with Powertrain Control Module computerized ignition system. PCM controls idle speed and air/fuel mixture. Adjustments are not required or possible.

THROTTLE POSITION SENSOR (TPS)

1. Turn ignition on. Check TPS output voltage at sensor
   wiring harness center terminal. At idle, output voltage should be
   greater than .2 volt.

2. Gradually open throttle plate. Output voltage should
   gradually increase as throttle plate is opened. At wide open throttle,
   output voltage must be less than 4.8 volts.

3. If voltages are not as specified, make sure 5-volt input
   and ground circuits between TPS and engine controller are okay. Repair
   circuits, if necessary. If TPS output voltages are still not as
   specified, replace TPS. Adjustment is not required or possible.

NOTE: Also see appropriate throttle position sensor tests in appropriate G - TESTS W/ CODES article.