Compression
Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions.
| WARNING | DO NOT use ignition switch during compression tests on fuel injected vehicles. Use a remote starter to crank engine. Fuel injectors on many models are triggered by ignition switch during cranking mode, which can create a fire hazard or contaminate the engine's oiling system. |
| Application | Psi (kPa) |
|---|---|
| Normal Compression Pressure | 170-225 (11.9-15.8) |
| Minimum Compression Pressure | 100 (690) |
| Maximum Variation Between Cylinders | (1) |
| (1) Maximum variation is 25 percent. | |
| (1) | Maximum variation is 25 percent. |
COMPRESSION SPECIFICATIONS
FUEL PRESSURE RELEASE
| WARNING | Always release fuel pressure before disconnecting any fuel injection-related component. DO NOT allow fuel to contact engine or electrical components. |
| CAUTION | When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See the COMPUTER RELEARN PROCEDURES article in the GENERAL INFORMATION section before disconnecting battery. |
- Ensure ignition is off. Disconnect negative battery cable. Remove fuel tank filler cap. Remove protective cap from service port on fuel rail.
- Service port is located near front (timing belt end) of fuel rail.
- Place end of Hose (C-4799-1) into an approved fuel container. Attach remaining end of hose at service port on fuel rail. Use care, as fuel system may be under pressure. Fuel pressure will be released from fuel system. Remove hose, reinstall protective cap, fuel tank filler cap and negative battery cable.
FUEL PUMP RELAY
Fuel pump relay is used to provide voltage to fuel pump. Fuel pump relay is located in power distribution center at driver's side front corner of engine compartment, near the battery. Fuel pump relay receives constant battery voltage at one side of relay from fuse No. 13 (20-amp) in power distribution center. When ignition is on, fuel pump relay receives voltage at the other side of the relay from Positive Temperature Coefficient (PTC) No. 1 in junction block located behind driv-er's side of instrument panel, to the left of steering column. PTC is a specified amperage solid-state circuit breaker. The Powertrain Control Module (PCM) controls the ground circuit for fuel pump relay. When ignition is on, PCM completes ground circuit for fuel pump relay and voltage is supplied to the fuel pump. If crankshaft position sensor does not detect engine rotation, the PCM opens the ground circuit and de-energizes the fuel pump.
If fuel pump relay or control circuit failure exists, a Diagnostic Trouble Code (DTC) may be stored in the PCM. See SELF-DIAGNOSTICS INTRODUCTION - FWD VANS article. For additional information on diagnosis for fuel pump relay and control circuit, see appropriate NO START (NS) TEST in TESTS W/CODES - 2.4L article.
IGNITION CHECKS
Note. For ignition system spark testing and component testing, see appropriate NO TROUBLE CODE (NTC) TEST and NO START (NS) TEST in the TESTS W/CODES - 2.4L article.
IDLE SPEED & IGNITION TIMING
Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see ADJUSTMENTS - 2.4L article.
SUMMARY
If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to the TESTS W/CODES - 2.4L article. If no diagnostic trouble codes are found in self-diagnostics, proceed to the TESTS W/O CODES - 2.4L article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.) or intermittent diagnostic procedures.