I have a 99 cherokee with 4.0. starts up everytime you hit the switch but after a couple of minutes the idle starts climbing and i final cut it off. RMPs climb to about 5000 before I cut it off.I have ran check on system using OBDII no codes. any Ideas??
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WELL YOU NEED TO DRAIN COOLANT LEVEL BELOW THERMOSTAT LEVEL.YOU HAVE TO DISCONNECT MAF SENSOR LOOSEN AIRDUCT 2 LARGE CLAMPS LOOSEN REMOVE 4 SCREWS TO AIR FILTER COVER LIFT UP REMOVE COVER. THEN REMOVE AIR FILTER AND HOUSING, FIRST DISCONNECT MAF SENSOR.YOU HAVE TO DISCONNECT THROTTLE CABLE AND SHIFT CABLE.YOU HAVE TO DISCONNECT REMOVE THROTTLE BODY COOLANT HOSES DISCONNECT IDLE SPEED CONTROL VALVE CONNECTOR AND DISCONNECT TPS SENSOR CONNECTOR. THEN REMOVE THROTTLE BODY ASSEMBLY. YOU NEED TO BUY NEW THROTTLE BODY COOLANT HOSES AND NEW THROTTLE BODY GASKET FOLLOW TOP COOLANT HOSE TO ENGINE BLOCK.NOW YOU SEE CAN AND REMOVE THE THERMOSTAT HOUSING REPLACE THE THERMOSTAT.BESURE TO HAVE EXTRA COOLANT ON HAND.BLEED COOLANT SYSTEM WHEN DONE.TO BLEED COOLANT SYSTEM REMOVE RADIATOR CAP ON OVERFLOW JUG.THEN OPEN BLEED SCREW ON THE WATER PUMP BYPASS HOSE PIPE JUST A LITTLE.POUR COOLANT IN THE OVERFLOW JUG UNTIL LEVEL STOP DROPPING.STOP AT COLD MARK ON JUG.CLOSE BLEEDER SCREW ON WATER PUMP BYPASS HOSE PIPE.CRANK VECHICLE CHECK FOR LEAKS. START UP ENGINE LET IDLE FEW MINUTES THEN CHECK COOLANT LEVEL ADD MORE UNTIL UNTIL LEVEL STOP DROPPING.PUT RADIATOR CAP BACK ON OVERFLOW RESERVOIR. LET ENGINE IDLE WATCH COOLANT TEMPERATURE GAUGE.WHEN GAUGE START CLIMBING. TURN OFF ENGINE WAIT FEW MINUTES TAKE A LARGE RAG OPEN RADIATOR JUST A LITTLE YOU HEAR HISS NOISE.WHEN PRESSURE STABILIZE DONT GET SCALDED BECAREFUL.OPEN CAP LITTLE MORE.IF COOLANT PRESSURE STILL BOILS OUT WAIT 20 MINUTES ADD MORE COOLANT TO RADIATOR OVER FLOW WHEN COOLANT LEVEL STOP DROPPING.PUT RADIATOR CAP BACK ON START VECHICLE UP LET IDLE UNTIL THERMOSTAT OPEN. THEN FEEL TOP RADIATOR HOSE FEELS HOT THERMOSTAT OPEN WATCH TEMPERATURE GAUGE.IF GAUGE TEMP START CLIMBING TURN OFF ENGINE WAIT A WHILE.CHECK AND ADD MORE COOLANT.WHEN THE ENGINE CAN IDLE TEMP GAUGE STOP CLIMBING YOU HAVE BLEED COOLANT SYSTEM.KEEP CHECK ON COOLANT LEVEL.
you need to have it connected to an OBD2 machine and watch if you are missing the cam sensor showing RPMs or if your missing crank sensors RPMs, it could be a wiring problem or computer if your seeing the RPMs from both sensors,and the last thing i would check is hooking up a fuel gauge to the reed valve and watch what fuel pressure you have while cranking,if the cam sensor is the culprit it will turn the fuel off after the cranking.