TERMINOLOGY
Due to federal government requirements, manufacturers may use names and acronyms for systems and components different than those used in previous years. The following table will help eliminate confusion when dealing with these components and systems. Only relevant components and systems whose names have changed from current General Motors Corp. terminology have been listed.
| Former Name Or Acronym | New Name Or Acronym |
|---|---|
| ALDL | Data Link Connector (DLC) |
| CHECK ENGINE Light | Malfunction Indicator Light (MIL) |
| CTS | Engine Coolant Temperature Sensor |
| Diagnostic Circuit Check | On-Board Diagnostic (OBD) System Check |
| ESC System | Knock Sensor (KS) System |
| EST System | Ignition Control (IC) System |
| MAT Sensor | Intake Air Temperature (IAT) Sensor |
| Park/Neutral (P/N) Switch | Park/Neutral Position (PNP) Switch |
| Port Fuel Injection | Multiport Fuel Injection |
| Scan Data | Scan Tester (ST) Data |
| SERVICE ENGINE SOON Light | Malfunction Indicator Light (MIL) |
| Thermostatic Air Cleaner (TAC) | Air Cleaner (ACL) |
| Throttle Position Sensor (TPS) | Throttle Position (TP) Sensor |
| Throttle Position Switch | Closed Throttle Position (CTP) Switch |
| Throttle Position Switch | Wide Open Throttle (WOT) Switch |
| Viscous Converter Clutch (VCC) | Torque Converter Clutch (TCC) |
| (1) Text includes old and new terminology. This is a representative listing. | |
| (1) | Text includes old and new terminology. This is a representative listing. |
SAE TERMINOLOGY (1)
Compression
Check engine mechanical condition using a compression gauge, vacuum gauge or engine analyzer. See engine analyzer manual for specific instructions. See COMPRESSION SPECIFICATIONS .
| Application | Specification |
|---|---|
| Compression Ratio | 9.5:1 |
| Normal Compression Pressure | 191 psi (1316.9 kPa) |
| Minimum Compression Pressure | 142 psi (979.1 kPa) |
| Maximum Variation Between Cylinders | 14 psi (96.5 kPa) |
COMPRESSION SPECIFICATIONS
Exhaust System Backpressure
Exhaust system can be checked using a vacuum or pressure gauge. If using a pressure gauge, remove O2 sensor or air injection check valve (if equipped). Connect a 1-10 psi pressure gauge. Operate engine at 2500 RPM. If exhaust system backpressure is greater than 2 psi, exhaust system or catalytic converter is plugged.
If using a vacuum gauge, connect vacuum gauge hose to intake manifold vacuum port. Start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for restriction.
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 PRESSURE RELEASE
Loosen fuel tank cap to release fuel tank pressure. Disconnect electrical connector on circuit opening relay attached to ECM, located under radio in instrument panel center console. Start engine. Idle engine until it dies. Crank engine for about 10 seconds to ensure residual fuel line pressure is released. Turn ignition off. Install circuit opening relay and remaining components.
FUEL PRESSURE
Note. For fuel pump specifications, see FUEL PUMP PERFORMANCE .
- Release fuel pressure. See «FUEL PRESSURE RELEASE»(ref-19795-S04867822402001010200000). Disconnect negative battery cable. Remove bolt and fuel inlet hose from fuel rail.
- Install Adapter (J-39802) with gaskets and fuel inlet hose to fuel rail. (Scheme 21) Tighten adapter retaining bolt to 22 ft. lbs. (29 N.m). Install Fuel Pressure Gauge (J-34730-1A) to adapter.
- Reconnect negative battery cable. Turn ignition on. Connect jumper wire between Data Link Connector (DLC) terminals B+ (Black/Red wire) and FP (Blue/Black wire). DLC is located on left strut tower. Check fuel pressure. see scheme 10or see scheme 20. Release fuel pressure. Remove fuel pressure gauge. Remove jumper wire from DLC.
Scheme 21
| Application | Pressure: psi (kg/cm 2 ) |
|---|---|
| Prizm & Prizm LSi | (1) (2) 38-44 (262.0-303.4) |
| (1) With ignition on, engine off, and jumper wire connected between DLC terminals B+ and FP. DLC is located on left strut tower. (2) With engine idling, jumper wire removed from DLC and pressure regulator vacuum hose disconnected and plugged. Reconnect vacuum hose. Pressure should decrease to 31-37 psi (213.7-255.1 kPa). | |
| (1) | With ignition on, engine off, and jumper wire connected between DLC terminals B+ and FP. DLC is located on left strut tower. |
| (2) | With engine idling, jumper wire removed from DLC and pressure regulator vacuum hose disconnected and plugged. Reconnect vacuum hose. Pressure should decrease to 31-37 psi (213.7-255.1 kPa). |
FUEL PUMP PERFORMANCE
IGNITION CHECKS
Note. For a no-start condition, see DIAGNOSTIC CHARTS.
SPARK
Crank engine, checking for a strong Blue spark at coil wire and each spark plug wire using Spark Tester (ST-125). If spark exists on some spark plugs, check for defective distributor cap and defective rotor. Check spark plug high tension wire resistance. Replace spark plug high tension wires if resistance exceeds specification. See HIGH TENSION WIRE RESISTANCE .
| Application | Ohms |
|---|---|
| All Models | (1) 3000-6500 |
| (1) Resistance for every 12" (305 mm) of wire. | |
| (1) | Resistance for every 12" (305 mm) of wire. |
HIGH TENSION WIRE RESISTANCE
IGNITION COIL POWER SOURCE
Ignition coil is located in distributor. Disconnect electrical connector from distributor. Turn ignition on. Using voltmeter, check voltage between Black/Orange wire of distributor connector and ground. If battery voltage does not exist, check for open circuit in Black/Orange wire between distributor connector and ignition switch.
IGNITION COIL RESISTANCE
Remove distributor cap, rotor and dust cover. Using an ohmmeter, measure primary and secondary resistance. (Scheme 22) Replace ignition coil if readings are not within specification. See IGNITION COIL RESISTANCE.
| Application | Primary | Secondary | |
|---|---|---|---|
| Prizm & Prizm LSi | |||
| Cold | 1.11-1.75 | 9,000-15,700 | |
| Hot | 1.41-2.05 | 11,400-18,400 | |
IGNITION COIL RESISTANCE - Ohms
Scheme 22
SIGNAL ROTOR/CAMSHAFT POSITION (CMP) SENSOR
Measure signal rotor/CMP sensor air gap. If gap is not .008-.016" (.20-.40 mm), adjust or replace distributor. Check signal rotor/CMP resistance. See I - SYS/COMP TESTS article in this section.
IDLE SPEED & IGNITION TIMING
Ensure idle speed and base ignition timing are set to specification. For adjustment procedures, see ADJUSTMENTS article in this section.
CHART A1-3, ENGINE CRANKS BUT WILL NOT RUN
When ignition switch is turned to ON or START position, voltage is applied to ignition coil and to ignitor (inside distributor). Ignitor controls ground circuit of ignition coil. When ignitor receives power and an ignition firing input, it toggles ground path to ignition coil on and off, inducing a high voltage in secondary winding of coil. This induced voltage is then applied through distributor cap to each spark plug.
Note. Test numbers refer to numbers on diagnostic chart.
- Checks for spark at distributor cap.
- Checks for faulty spark plug wires or misadjusted signal rotor air gap.
CHART A1-5, FUEL INJECTOR CIRCUIT CHECK (ENGINE NO-START)
When ignition switch is turned to ON or START position (engine running), ECM will energize/de-energize fuel injector solenoid coil. With coil energized, a plunger is activated, allowing pressurized fuel to be sprayed through fuel injectors into combustion chamber where it is mixed with air from intake manifold, thus creating proper air/fuel mixture needed for combustion.
Note. Test numbers refer to numbers on diagnostic chart.
- Checks if ECM is controlling ground path to fuel injectors.
- Checks resistance of fuel injectors.
- Checks for open or short to ground in Black or Black/Red wire between fuel injectors and ECM, or for faulty fuel injectors or ECM.
CHART A2-3, ENGINE CRANKS BUT WILL NOT RUN
When ignition switch is turned to ON or START position, voltage is applied to ignition coil and to ignitor (inside distributor). Ignitor controls ground circuit of ignition coil. When ignitor receives power and an ignition firing input, it toggles ground path to ignition coil on and off, inducing a high voltage in secondary winding of coil. This induced voltage is then applied through distributor cap to each spark plug.
Note. Test numbers refer to numbers on diagnostic chart.
- Checks for spark at distributor cap.
- Checks for faulty spark plug wires or misadjusted signal rotor air gap.
CHART A2-5, FUEL INJECTOR CIRCUIT CHECK (ENGINE NO-START)
With ignition switch in ON or START position (engine running), PCM will energize/de-energize fuel injector solenoid coil. With coil energized, a plunger is activated, allowing pressurized fuel to be sprayed through fuel injectors into combustion chamber where it is mixed with air from intake manifold, creating proper air/fuel mixture needed for combustion.
Note. Test numbers refer to numbers on diagnostic chart.
- Checks if PCM is controlling ground path of fuel injectors.
- Checks resistance of fuel injectors.
- Checks for an open or short to ground in Black or Black/Red wire between fuel injectors and PCM, or for faulty fuel injectors or PCM.
SUMMARY
If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, go to TESTS W/CODES article in this section. If no hard codes are found in self-diagnostics, go to appropriate TESTS W/O CODES article in this section for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.