DRIVE BELT TENSION
| Application | (1) Tension - Lbs. (kg) |
|---|
| 2.5L, 2.8L & 3.1L | (1) |
| 4.3L, 5.0L & 5.7L |
| New Belt | 135 (61.2) |
| Used Belt | 90 (40.8) |
| 6.2L Diesel |
| New Belt | 146 (66.2) |
| Used Belt | 67 (30.4) |
| 7.4L |
| New Belt | 129.4-140.6 (58.7-63.8) |
| Used Belt | 84.4-95.6 (38.3-43.4) |
| (1) Serpentine belt tension is maintained automatically by a spring-tensioned idler pulley. No adjustment is necessary. |
| (1) | Serpentine belt tension is maintained automatically by a spring-tensioned idler pulley. No adjustment is necessary. |
ENGINE COMPRESSION
| Application | Compression Ratio |
|---|
| 2.5L (VIN E) | 8.3:1 |
| 2.8L (VIN R) | 8.9:1 |
| 3.1L (VIN D) | 8.9:1 |
| 4.3L (VIN Z) | (1) 9.3:1 |
| 5.0L (VIN H) | 9.3:1 |
| 5.7L (VIN K) | (2) 9.1:1 |
| 6.2L Diesel (VIN C & J) | 21.3:1 |
| 7.4L (VIN N) | 7.9:1 |
| (1) 8.6:1 on Turbo & heavy duty. (2) 8.3:1 on vehicles over 8500 lbs. GVW. |
| (1) | 8.6:1 on Turbo & heavy duty. |
| (2) | 8.3:1 on vehicles over 8500 lbs. GVW. |
COMPRESSION SPECIFICATIONS
VALVE CLEARANCE
Note. All models are equipped with hydraulic lifters. No adjustments are required.
IGNITION COIL
| Application | Ohms |
|---|
| All Models | 500-1500 |
HIGH TENSION WIRE RESISTANCE
| Application | Ohms |
|---|
| All Models | 30,000 Maximum |
HIGH TENSION WIRE RESISTANCE
SPARK PLUGS
| Application | AC |
|---|
| 2.5L (VIN E) | R43TS6 |
| 2.8L (VIN R) | R43TSK |
| 3.1L (VIN D) | R43TS |
| 4.3L (VIN Z) |
| Non-Turbo | CR43TS |
| Turbo | CR42TS |
| 5.0L (VIN H) | CR43TS |
| 5.7L (VIN K) | CR43TS |
| 7.4L (VIN N) | CR43TS |
| Application | Gap: In. (mm) | Torque: Ft. Lbs. (N.m) |
|---|
| 2.5L (VIN E) | .060 (1.52) | 17 (23) |
| 2.8L (VIN R) | .045 (1.14) | 22 (30) |
| 3.1L (VIN D) | .045 (1.14) | 18 (24) |
| 4.3L (VIN Z) |
| Non-Turbo | .035 (0.89) | 22 (30) |
| Turbo | .045 (1.14) | 11 (15) |
| 5.0L (VIN H) | .035 (0.89) | 22 (30) |
| 5.7L (VIN K) | .035 (0.89) | 22 (30) |
| 7.4L (VIN N) | .035 (0.89) | 22 (30) |
SPARK PLUG SPECIFICATIONS
Firing Order & Timing Marks (2.5L). Scheme 1
Scheme 1: Firing Order & Timing Marks (2.5L)
Firing Order & Timing Marks (2.8L). Scheme 2
Scheme 2: Firing Order & Timing Marks (2.8L)
Firing Order & Timing Marks (3.1L). Scheme 3
Scheme 3: Firing Order & Timing Marks (3.1L)
Firing Order & Timing Marks (4.3L). Scheme 4
Scheme 4: Firing Order & Timing Marks (4.3L)
Firing Order & Timing Marks (5.0L, 5.7L & 7.4L). Scheme 5
Scheme 5: Firing Order & Timing Marks (5.0L, 5.7L & 7.4L)
Firing Order (6.2L Diesel). Scheme 6
Scheme 6: Firing Order (6.2L Diesel)
IGNITION TIMING
Note. For timing procedures, see appropriate ADJUSTMENTS article in this section.
| Application | (1) Man. Trans. | (2) Auto. Trans. |
|---|
| 2.5L (VIN E) | 8 @ Idle | 8 @ Idle |
| 2.8L (VIN R) | 10 @ Idle | 10 @ Idle |
| 3.1L (VIN D) | 10 @ Idle | 10 @ Idle |
| 4.3L (VIN Z) | 0 @ Idle | 0 @ Idle |
| 5.0L (VIN H) | 0 @ Idle | 0 @ Idle |
| 5.7L (VIN K) | 0 @ Idle | 0 @ Idle |
| 7.4L (VIN N) | 4 @ Idle | 4 @ Idle |
| (1) With transmission in Neutral. (2) With transmission in Neutral or Park. |
| (1) | With transmission in Neutral. |
| (2) | With transmission in Neutral or Park. |
IGNITION TIMING (Degrees BTDC @ RPM)
FUEL PUMP
| Application | Psi (kg/cm 2 ) |
|---|
| 4.3L Turbo (VIN Z) | 35-38 (2.5-2.7) |
| 6.2L Diesel (VIN C & J) | 6-9 (.42-.63) |
| All Others | 9-13 (.63-.91) |
INJECTOR RESISTANCE
| Application | (1) Resistance (Ohms) |
|---|
| 3.1L (VIN D) | 1.2 |
| 4.3L Turbo (VIN Z) | 2.0 |
| All Others | 1.3 |
| (1) Injector resistance specification is at 140°F (60°C). |
| (1) | Injector resistance specification is at 140°F (60°C). |
INJECTOR RESISTANCE SPECIFICATIONS
IDLE SPEED & MIXTURE
Note. Idle mixture on fuel injected models is controlled by the Electronic Control Module (ECM) and is not adjustable.
THROTTLE POSITION SENSOR (TPS)
Note. TPS is adjustable only on 2.8L (VIN R) and 6.2L Diesel engines. For further testing, see the appropriate articles below
- «TESTS W/CODES - DIESEL»(ref-10254)
- «TESTS W/CODES - GASOLINE»(ref-10255)
| Application | (1) Voltage |
|---|
| 2.8L (VIN R) | .42-.45 |
| 6.2L Diesel (VIN C & J) | (2) .63 |
| (1) At idle RPM or closed throttle. (2) This is TPS voltage ratio. For adjustment procedure, see ADJUSTMENTS article in this section. |
| (1) | At idle RPM or closed throttle. |
| (2) | This is TPS voltage ratio. For adjustment procedure, see ADJUSTMENTS article in this section. |
