Compression
Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. If compression gauge is used, see COMPRESSION SPECIFICATIONS table. Ensure engine cranking speed is about 300 RPM. If vacuum gauge is used, check for low or unstable vacuum condition. If engine analyzer is used, see manufacturer's manual for specific instructions.
| Application | Specification |
|---|
| Compression Pressure (1) (2) |
| 2.2L | (3) |
| 3.2L | 200 psi (1380 kPa) |
| 3.5L | 200 psi (1380 kPa) |
| Compression Pressure (Minimum) |
| 2.2L | (3) |
| 3.2L | 145 psi (1000 kPa) |
| 3.5L | 145 psi (1000 kPa) |
| Compression Ratio |
| 2.2L | 10.0:1 |
| 3.2L & 3.5L | 9.1:1 |
| (1) Measured at 300 RPM. (2) Maximum difference between cylinders 14.5 psi (100 kPa). (3) Information not available from manufacturer. |
| (2) | Maximum difference between cylinders 14.5 psi (100 kPa). |
| (3) | Information not available from manufacturer. |
COMPRESSION SPECIFICATIONS
Exhaust System Backpressure
The exhaust system can be checked with a vacuum or pressure gauge. If using a pressure gauge, remove oxygen sensor or air injection check valve (if equipped). Connect a 0-5 psi pressure gauge and run engine at 2000 RPM. If exhaust system backpressure is greater than 2 psi, exhaust system or catalytic converter is plugged.
If a vacuum gauge is used, connect vacuum gauge hose to intake manifold vacuum port and start engine. Open throttle part way and hold. Observe vacuum gauge. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for restriction.
ENGINE CRANKS BUT WILL NOT RUN (RODEO & RODEO SPORT 2.2L)
| WARNING | Relieve fuel pressure before connecting fuel pressure gauge. See FUEL SYSTEM PRESSURE RELEASE under FUEL SYSTEM. |
ENGINE CRANKS BUT WILL NOT RUN (AXIOM 3.5L, PASSPORT, RODEO & RODEO SPORT 3.2L)
| WARNING | Relieve fuel pressure before connecting fuel pressure gauge. See FUEL SYSTEM PRESSURE RELEASE under FUEL SYSTEM. |
ENGINE CRANKS BUT WILL NOT RUN (TROOPER 3.5L)
| WARNING | Relieve fuel pressure before connecting fuel pressure gauge. See FUEL SYSTEM PRESSURE RELEASE under FUEL SYSTEM. |
FUEL SYSTEM
| WARNING | Always relieve fuel pressure before disconnecting any fuel injection related component. DO NOT allow fuel to contact engine or electrical components. |
FUEL SYSTEM PRESSURE RELEASE
Loosen fuel tank filler cap to relieve tank pressure. Remove fuel pump relay from underhood fuse/relay box. Start and operate engine until it stalls. Crank engine an additional 3 seconds.
FUEL INJECTOR RESISTANCE
| Application | Ohms |
|---|
| 2.2L, 3.2L & 3.5L | (1) 11.8-12.6 |
| (1) For proper fuel injector test procedure, see FUEL INJECTION in SYSTEM & COMPONENT TESTING article. |
| (1) | For proper fuel injector test procedure, see FUEL INJECTION in SYSTEM & COMPONENT TESTING article. |
IGNITION COIL
| Application | Primary | Secondary |
|---|
| 2.2L | (1) | (1) |
| 3.2L | (2) | (2) |
| 3.5L | (2) | (2) |
| (1) Information is not available from manufacturer. (2) Use DVOM to measure resistance between terminals No. 1-2, 1-3 and 2-3. (Scheme 3) If resistance reading between any two terminals is 0 ohms (shorted) or infinity (open), replace ignition coil assembly. |
| (1) | Information is not available from manufacturer. |
| (2) | Use DVOM to measure resistance between terminals No. 1-2, 1-3 and 2-3. (Scheme 3) If resistance reading between any two terminals is 0 ohms (shorted) or infinity (open), replace ignition coil assembly. |
IGNITION COIL RESISTANCE - Ohms @ 68°F (20°C)
Scheme 3
IDLE SPEED
| Application | RPM |
|---|
| 2.2L, 3.2L & 3.5L (1) | 750 |
| (1) Idle speed is controlled by PCM and is not adjustable. |
| (1) | Idle speed is controlled by PCM and is not adjustable. |
IDLE SPEED SPECIFICATIONS
IGNITION TIMING
Note. All models are equipped with electronic computer-controlled ignition system. Ignition timing is not adjustable.
SUMMARY
If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to appropriate SELF-DIAGNOSTICS article. If no hard codes are found in self-diagnostics, (if vehicle has self-diagnostic system) proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.
