Tune-Up - v6 Dodge Caravan I

ENGINE IDENTIFICATION

Engine can be identified by a number stamped on a pad on right side of block (below No. 6 spark plug).

Engine can also be identified by eighth character of Vehicle Identification Number (VIN). VIN is located on a Gray plate attached to left corner of instrument panel and is visible through windshield.

ENGINE CODES

TUNE-UP NOTES

Note. Always refer to Emission Control Label in engine compartment before attempting tune-up. If manual and label differ, always use emission label specifications. When performing tune-up procedures, the following notes and precautions must be followed

When performing tune-up on vehicles equipped with catalytic converters, do not allow or create a condition of engine misfire in more than one cylinder for an extended period of time. Total test time must not exceed 10 minutes or damage to converter may occur due to loading converter with unburned air/fuel mixture.

When inspecting distributor rotor, a Black silicone varnish will be noticed covering .20-.30" (.50-.80 mm) of rotor electrode tip. This replaces earlier silicone grease used to suppress electro magnetic radiation. Grease will darken with age, has an ash-like appearance and should not be removed. Ash formation (on both types of coverage) is normal and does not affect engine performance.

If it becomes necessary to replace the Spark Control Computer (SCC), do not disassemble computer for any reason. It is not serviceable and must be replaced as an assembly.

ENGINE COMPRESSION

Before performing compression test or cranking engine using remote starting switch, disconnect coil wire from distributor and secure to good ground. Check compression with engine warm, spark plugs removed and throttle wide open.

COMPRESSION SPECIFICATIONS

SPARK PLUGS

SPARK PLUG TYPE

SPARK PLUG SPECIFICATIONS

HIGH TENSION WIRE RESISTANCE

Note. Resistance type spark plug wires are identified by the words "Electronic Suppression" printed on cable jacket. Use an ohmmeter to check for open circuits, loose terminals and/or high resistance.

1. Carefully remove each spark plug wire from spark plugs. Detach coil wire from coil. Remove distributor cap without removing coil and spark plug wires.
2. Connect one ohmmeter lead to the coil or spark plug end of wire. Connect other ohmmeter lead to electrode inside distributor cap. Repeat procedure for the coil wire.
3. If resistance is not within specification, replace spark plug wire assembly and/or coil cable. Be sure to check ignition coil tower for carbon tracking, cracks and oil leaks.

HIGH TENSION WIRE RESISTANCE (OHMS)

Vacuum Test (3.9L)

Disconnect inlet and outlet fuel lines from fuel pump. Connect vacuum gauge to fuel pump inlet fitting. Using starter motor, turn engine over several times and observe vacuum gauge. Fuel pump should develop a minimum of 11 in. Hg. vacuum. If not, replace pump.

Pressure Test

Connect a pressure gauge to fuel pump outlet fitting. Using starter motor, turn engine over several times and observe pressure gauge. If pump does not develop specified pressure, replace pump.

FUEL PUMP SPECIFICATIONS

3.0L

1. I-E-I-E-I-E (Right bank, front-to-rear).
2. E-I-E-I-E-I (Left bank, front-to-rear).

3.9L

1. I-E-E-I-I-E (Right bank, front-to-rear).
2. E-I-I-E-E-I (Left bank, front-to-rear).

VALVE CLEARANCE

The overhead camshaft 3.0L engine is equipped with hydraulic valve lash adjusters which are installed in the rocker arms. There is no measurable valve clearance. The hydraulic lash adjusters may be replaced. See 3.0L V6 CHRYSLER ENGINE in ENGINES section.

The 3.9L engine is equipped with hydraulic lifters and valve adjustment is not necessary. Valve clearance is at zero lash with engine at operating temperature.

Scheme 13

Scheme 14

DISTRIBUTOR

The 3.0L engine is equipped with Mitsubishi Electronic Ignition System (EIS). The 3.9L engine uses Chrysler Hall Effect Electronic Spark Advance (ESA) ignition system.

The only adjustments that can be made to either system are initial ignition timing (changing distributor position) and spark plug gap.

Scheme 15

Scheme 16

IGNITION TIMING (3.9L)

1. If a magnetic probe timing light is used, refer to equipment manufacturer's instruction for proper hookup. Use a 10 degree offset when required.
2. Turn off all lights and accessories. Disconnect and plug vacuum line at Spark Control Computer (if equipped), or at distributor. Connect a jumper wire between carburetor switch and ground (if equipped).
3. Connect tachometer to engine. Connect power timing light to No. 1 cylinder. Start engine and run in Neutral on second step of fast idle cam until normal operating temperature is reached. Ensure engine is running at or below curb idle RPM. If not, adjust curb idle. See HOT (SLOW) IDLE RPM in this article.
4. Quickly open and release throttle to ensure linkage does not bind and that idle speed screw is against its stop. Aim power timing light at timing marks or read magnetic timing unit. IGNITION TIMING SPECIFICATIONS (DEGREES BTDC @ RPM) Application Man. Trans. Auto. Trans. 3.9L 2-Bbl. 7 @ 720 7 @ 700 CAUTION: Do not use distributor vacuum advance chamber as a turning handle when rotating distributor.
5. If timing is not within plus or minus 2 degrees of specification, loosen distributor hold-down arm screw and rotate distributor housing to obtain correct timing. Tighten distributor hold-down screw when timing is correct.
6. Recheck idle speed and timing. If curb idle is not within plus or minus 50 RPM of specification, readjust idle and recheck timing. Repeat procedure until both idle speed and timing are correct. Turn engine off, reconnect vacuum lines and remove jumper wire and tachometer.

IGNITION TIMING (3.0L MPFI)

1. Set gear shift selector in "Park" or "Neutral" and apply parking brake. Turn off all lights and accessories. Connect power timing light to No. 1 cylinder or use magnetic timing probe equipment.
2. Start engine and run until normal operating temperature is reached. Disconnect coolant temperature sensor wires. The I/P lamp should come on. Ensure engine is running at or below curb idle RPM. Aim timing light at timing marks or read magnetic timing unit. IGNITION TIMING SPECIFICATIONS (DEGREES BTDC @ RPM) Application Man. Trans. Auto. Trans. 3.0L MPFI Initial N/A 12 @ 800 Total N/A 38+/-4 @ 2000
3. If timing is not within +/-2 degrees of specification, loosen distributor hold-down and rotate distributor to obtain correct timing. Tighten distributor hold-down when timing is correct. Turn engine off. Reconnect coolant temperature wire connector and erase fault code.

ELECTRONIC SPARK ADVANCE (ESA) CHECK

Note. Due to unique cold engine spark advance schedules (which change during engine warm-up), ensure spark advance testing is done with fully warmed engine and properly connected and operating temperature sensor.

1. Set ignition basic timing. Remove and plug vacuum line at vacuum transducer. Connect auxiliary vacuum source to transducer and set vacuum at 16 in. Hg.
2. With engine warm, run engine at 2000 RPM for one minute (or accumulator clock up time), then check spark advance. See ELECTRONIC SPARK ADVANCE SPECIFICATIONS. Advance specifications are in addition to basic advance. Replace computer if advance is incorrect.

3.9L ELECTRONIC SPARK ADVANCE SPECIFICATIONS (1)

Note. Fuel system adjustments on the 3.0L MPFI engine are not part of a normal tune-up. For additional information on Chrysler MPFI systems see FUEL SYSTEM section.

1. Ensure that ignition timing is properly adjusted. Disconnect and plug vacuum hose at EGR valve and the air switching valve. Also disconnect and plug vacuum hose from carburetor at heated air temperature sensor. Remove air cleaner and disconnect and plug 3/16" diameter control hose at canister.
2. Remove PCV valve from cylinder head cover and allow valve to draw underhood air. Install tachometer. Start and warm engine to normal operating temperature. Allow engine to run at idle for one minute to stabilize idle.
3. Check idle speed. Adjust idle speed screw to obtain correct idle RPM.
4. Turn off engine and remove tachometer. Reconnect all vacuum lines and hoses. Reinstall PCV valve.

Note. After adjustment, idle speeds may vary from specifications. This is normal and no readjustment is necessary.

IDLE MIXTURE

Note. Idle mixture adjustment is not part of a regular tune-up. DO NOT adjust mixture unless carburetor has been disassembled or vehicle fails emissions testing.

Mixture Plug Removal

1. Remove air cleaner. Disconnect and mark (for reassembly) all vacuum hoses from front of carburetor. Center punch idle mixture screw housing 1/4" from end of housing. (Scheme 17)
2. Drill through outer section of housing at punch mark with 3/16" drill. Pry plug out of housing and save for reassembly. Reconnect vacuum hoses and install air cleaner.

Scheme 17

Propane Enrichment Procedure

1. Remove concealment plug. Set parking brake and place transmission in Neutral. Turn all lights and accessories off. Connect tachometer to engine. Start engine and allow to warm up on second highest step of fast idle cam until normal operating temperature is reached. Return to idle and turn engine off.
2. Remove air cleaner Disconnect and plug vacuum line at EGR valve and air pump switching valve. Disconnect vacuum supply hose from choke diaphragm at the "Tee" fitting and install propane supply hose. Other connections at "Tee" fitting must remain in place.
3. With propane bottle held upright and in a safe location, remove PCV valve from rocker cover and allow valve to draw underhood air. Disconnect and plug 3/16" diameter control hose from canister.
4. Allow engine to run for 2 minutes to stabilize idle. Open propane main valve. Slowly open propane metering valve until maximum RPM is reached (too much propane will decrease RPM). "Fine tune" metering valve to obtain highest engine RPM. With propane still flowing, adjust idle speed screw on solenoid to reach specified RPM.
5. Adjust metering valve again to reach maximum RPM. If there has been a change in maximum RPM, readjust idle speed screw to specified RPM. Turn off propane main valve and allow engine speed to stabilize. Slowly adjust idle mixture screw (1/16 turn at a time), waiting 30 seconds between adjustments, until smoothest idle at specified RPM is reached.
6. Turn on propane main valve and "fine tune" metering valve to obtain highest engine RPM. If maximum RPM is more than 25 RPM different from specified RPM, repeat steps 4) and 5).
7. Turn off propane main valve and metering valve. Remove propane supply hose and carburetor switch ground wire. Reconnect oxygen sensor lead and all vacuum hoses. Remove test equipment. Install concealment plug. Perform all idle speed adjustments.

Note. After adjustment, specified RPM may vary. This is normal and does not require readjustment.

1. Ensure that ignition timing is properly adjusted. Turn off all lights and accessories. Disconnect and plug vacuum lines at EGR valve, distributor and 3/16" diameter control hose at canister. Disconnect and plug vacuum line from carburetor at heated air temperature sensor.
2. Remove PCV valve from cylinder head cover and allow valve to draw underhood air. Install a tachometer. Start and warm engine to normal operating temperature.
3. Open throttle slightly and place fast idle adjustment screw on second highest step of fast idle cam. With choke fully open, turn fast idle adjustment screw to obtain proper fast idle RPM.
4. Return to idle speed, then reposition fast idle adjustment screw on second highest step of fast idle cam. Check fast idle RPM and readjust if required. Return to idle speed and turn off engine. Remove test equipment and reconnect all components.

Note. After adjustment, fast idle speed may vary from set speed under normal operating conditions (all wires and hoses connected). This is normal and does not require re-adjustment.

Scheme 18

All models are equipped with non-adjustable choke covers. However, choke linkage and shaft must move freely hot or cold. Choke rods must be examined carefully for damage or bending. Use caution when installing carburetor to prevent damaging of choke rod. Do not force rod if it becomes trapped. Release it by removal only.

CHOKE VALVE SHAFT

1. To prevent choke from sticking due to gum deposits on shaft, spray Mopar Combustion Chamber Conditioner (4318001) onto choke shaft where it passes through air horn. NOTE: Service choke valve shaft, fast idle cam and pivot pin every 12,000 miles for heavy duty models and every 30,000 miles on light duty models or every 12 months, whichever comes first.
2. Move choke blade back and forth to distribute solvent. Apply solvent to fast idle cam and pivot pin to remove dirt, oil and other deposits that may have collected which could cause sticking or erratic motion.

3.0L engines use Mitsubishi Electronic Ignition Systems (EIS). All 3.9L engines use Chrysler Hall Effect Electronic Spark Advance (ESA) ignition system.

The only adjustments that can be made to either system are initial ignition timing (changing distributor position) and spark plug gap.

IGNITION COIL RESISTANCE (OHMS) (1)

EMISSION CONTROL

For information on emission control systems, see EMISSION section.

FUEL SYSTEM

FUEL INJECTION & CARBURETOR

BATTERY

BATTERY SPECIFICATIONS

STARTER

All models use gear reduction type starter.

STARTER TEST SPECIFICATIONS (1)

ALTERNATOR

ALTERNATOR SPECIFICATIONS

ALTERNATOR REGULATOR

Voltage regulation on 3.0L models is controlled by the Single Module Engine Controller (SMEC).

The 3.9L models use Chrysler Motors Electronic Voltage Regulator. Unit is nonadjustable. Ensure battery specific gravity is above 1.200 when checking regulated voltage.

REGULATOR OPERATING VOLTAGE @ 80°F (27°C)

DRIVE BELT

DRIVE BELT ADJUSTMENT

SERVICE INTERVALS

REPLACEMENT INTERVALS

CAPACITIES

COOLING SYSTEM CAPACITIES

ENGINE OIL & FUEL CAPACITIES

TRANSMISSION, TRANSFER CASE & DIFFERENTIAL CAPACITIES

A/C SYSTEM REFRIGERANT CAPACITIES