ENGINE COMPRESSION
Check engine compression at specified cranking speed with engine at normal operating temperature, all spark plugs removed (on dual plugs, remove exhaust side only) and throttle wide open. Ensure crankcase is full and oil is correct viscosity. With compression gauge installed, use remote starter to crank engine.
Crank engine at least 5 revolutions, and record highest reading. Repeat procedure for all cylinders using approximately same number of revolutions. Lowest compression reading should not be less than 75 percent of highest compression reading. No cylinder compression reading should be less than 100 psi (7 kg/cm 2 ).
| Application | Compression Ratio |
|---|---|
| 2.9L & 4.0L | 9.0:1 |
| 3.0L | 9.3:1 |
COMPRESSION RATIO SPECIFICATIONS
VALVE CLEARANCE
Note. On 2.9L models, valve clearance is set by turning adjusting screw an additional 1 1/2 turns past zero lash. On all other models, no valve adjustment is required as hydraulic valve lifters are used. If incorrect valve clearance is suspected, collapse lifter before checking clearance.
| Application | In. (mm) |
|---|---|
| 2.9L | (1) |
| 3.0L | .088-.189 (2.23-4.77) |
| 4.0L | (2) |
| (1) Valve clearance is set by turning adjusting screw an additional 1 1/2 turns past zero lash. (2) Information not available. | |
| (1) | Valve clearance is set by turning adjusting screw an additional 1 1/2 turns past zero lash. |
| (2) | Information not available. |
COLLAPSED VALVE LIFTER CLEARANCE
IGNITION COIL
| Application | Primary (Ohms) | Secondary (Ohms) |
|---|---|---|
| 2.9L & 3.0L TFI-IV | .8-1.6 | 8000-11,500 |
| 4.0L EDIS | .5 | (1) ** |
| (1) Information not available. | ||
| (1) | Information not available. |
IGNITION COIL RESISTANCE
HIGH TENSION WIRE RESISTANCE
| Application | Ohms |
|---|---|
| DIS, EDIS & TFI-IV | 7000 Per Foot |
HIGH TENSION WIRE RESISTANCE
IGNITION TIMING
| Application (1) | Degrees BTDC @ RPM | |
|---|---|---|
| 2.9L | ||
| Automatic Transmission | 10 @ 800 | |
| Manual Transmission | 10 @ 850 | |
| 3.0L | 10 @ Idle (2) | |
| 4.0L | Timing Not Adjustable | |
| (1) With SPOUT in-line connector disconnected. (2) Idle speed is not adjustable. | ||
| (1) | With SPOUT in-line connector disconnected. |
| (2) | Idle speed is not adjustable. |
BASE IGNITION TIMING
FUEL PUMP
Note. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article.
Note. Fuel pump performance is a measurement of fuel pressure and volume availability, not regulated fuel pressure.
| Application | Specification |
|---|---|
| Pressure | (1) |
| Volume | 1.5 pts. (.72L) in 30 seconds |
| (1) For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. | |
| (1) | For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. |
FUEL PUMP PERFORMANCE
IDLE SPEED & MIXTURE
Note. No idle mixture adjustments are possible. If engine performance is unsatisfactory, see TESTS W/CODES article in this section.
FAST IDLE SPEED
Note. Refer to underhood engine decal for engine fast idle RPM specification.