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Engine Controls - Basic Testing: Other Toyota Avalon XX10

Testing & Diagnostics 3 illustrations ~878 words

Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or engine analyzer. See engine analyzer manual for specific instructions.

WARNINGDO NOT use ignition switch during compression tests. 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.
ApplicationPsi (kg/cm 2 )
Normal Compression Pressure218 (15.3)
Minimum Compression Pressure145 (10.1)
Maximum Variation Between Cylinders15 (1.1)

COMPRESSION SPECIFICATIONS

FUEL SYSTEM

Basic diagnosis of fuel system should begin by checking fuel pump operation and fuel pressure.

WARNINGALWAYS relieve fuel pressure before disconnecting any fuel injection-related component. DO NOT allow fuel to contact engine or electrical components.

FUEL PRESSURE

Note. In-tank fuel pump is used. Fuel pump contains internal relief valve and check valve.

  1. Ensure battery is fully charged and ignition is off. Disconnect negative battery cable.
  2. Note location of fuel pressure gauge installation. (Scheme 51) Place container under delivery pipe or fuel filter. Cover union bolt with shop towel. Slowly loosen union bolt to relieve fuel pressure.
  3. Remove union bolt and gaskets. Install Fuel Pressure Gauge (SST 09268-45012) using NEW gaskets. (Scheme 51) Tighten union bolt. Reconnect negative battery cable.
  4. Install scan tester on data link connector No. 3. see scheme 1 Using scan tester manufacturer's instructions, activate electric fuel pump and note fuel pressure. Fuel pressure should be within specification. See «FUEL PUMP PERFORMANCE»(ref-21707-S25230609902001010300000) table. NOTE: Fuel pump may also be activated by connecting battery voltage to specified terminals on fuel pump. see scheme 2
  5. If fuel pressure exceeds specification, replace fuel pressure regulator. If fuel pressure is less than specified, check for defective fuel lines, connections, fuel pump, fuel filter, fuel pressure regulator or fuel pressure control Vacuum Switching Valve (VSV) if equipped.
  6. Remove scan tester from data link connector No. 3. Start engine and allow to idle. Disconnect and plug vacuum line at fuel pressure regulator. Note fuel pressure.
  7. Reconnect vacuum hose on fuel pressure regulator and note fuel pressure. Fuel pressure should be within specification. See the «REGULATED FUEL PRESSURE»(ref-21707-S19909700092001010300000) table.
  8. If fuel pressure is not within specification, check for defective vacuum hose or fuel pressure regulator. Shut engine off and note fuel pressure.
  9. Fuel pressure should hold at least 21 psi (1.5 kg/cm 2 ) for a minimum of 5 minutes. If fuel pressure does not hold as specified, check for defective fuel pump, fuel injector or fuel pressure regulator.
  10. Disconnect negative battery cable. Remove fuel pressure gauge. Reinstall union bolt using NEW gaskets. Tighten union bolt. Install negative battery cable.

Scheme 51

Scheme 51
Scheme 51
ApplicationPsi (kg/cm 2 )
V638-44 (2.7-3.1)

FUEL PUMP PERFORMANCE

Application TypeAt Idle W/VacuumAt Idle W/O Vacuum
Avalon33-38 (2.3-2.7)38-44 (2.7-3.1)

REGULATED FUEL PRESSURE

FUEL PUMP CONTROL CIRCUIT

Note. For information on testing relays and fuel system components, see the SYSTEM/COMPONENT TESTS article. Relays may be identified by illustration in the THEORY/OPERATION article. Vehicles are equipped with different combinations of fuel system electrical components. For complete wiring circuit of electrical components on a specific model, see wiring diagram in WIRING DIAGRAMS article.

EFI Main Relay

The EFI fuse supplies constant battery voltage to EFI main relay. When EFI main relay is energized by ignition switch, EFI main relay provides battery voltage to circuit opening relay (some models), data link connector No. 1 and various other electrical components. The EFI main relay may also provide battery voltage to +B terminal of ECM when ignition is turned on. The EFI main relay is located in engine compartment relay box.

Circuit Opening Relay

Circuit opening relay is used for the fuel pump circuit. When EFI main relay is energized, EFI main relay provides battery voltage to circuit opening relay. Fuel pump control side of circuit opening relay ground circuit is controlled at Engine Control Module (ECM) terminal FC. When circuit opening relay is grounded, the contacts close, providing voltage to fuel pump for fuel pump operation. Circuit opening relay is located in relay box.

IGNITION COIL RESISTANCE

  1. Disconnect negative battery cable. Remove cover located above ignition coils. Disconnect electrical connectors from ignition coils.
  2. Using ohmmeter, measure ignition coil primary resistance between positive (+) and negative (-) terminals of each ignition coil. These are the terminals that electrical connector was installed on.
  3. Replace ignition coil if primary resistance is not .54-.84 ohms at 14-122°F (-10-50°C) and .68-.98 ohms at 122-212°F (50-100°C). Ignition coil secondary resistance cannot be measured. Reinstall electrical connectors on ignition coils, cover and negative battery cable.

CAMSHAFT POSITION SENSOR

  1. Disconnect electrical connector from camshaft position sensor, located on rear corner of front cylinder head, just below valve cover. (Scheme 52) Using ohmmeter, measure resistance between electrical terminals on camshaft position sensor. (Scheme 52)
  2. Replace camshaft position sensor if resistance is not 835-1400 ohms at 14-122°F (-10-50°C) and 1060-1645 ohms at 122-212°F (50-100°C). Reinstall electrical connector on camshaft position sensor.

Scheme 52

Scheme 52
Scheme 52

CRANKSHAFT POSITION SENSOR

  1. Disconnect electrical connector from crankshaft position sensor, located near crankshaft pulley. (Scheme 53)
  2. Manufacturer recommends removing crankshaft position sensor before checking the resistance. Remove bolt and crankshaft position sensor.
  3. Using ohmmeter, measure resistance between electrical terminals on crankshaft position sensor. Replace crankshaft position sensor if resistance is not 1630-2740 ohms at 68°F (20°C) and 2060-3225 ohms at 122-212°F (50-100°C).
  4. Reinstall crankshaft position sensor. Install and tighten crankshaft position sensor bolt to 71 INCH lbs. (8.0 N.m). Reinstall electrical connector on crankshaft position sensor.

Scheme 53

Scheme 53
Scheme 53

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see the ADJUSTMENTS article.

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to the TESTS W/CODES article. If no hard diagnostic trouble codes are found in self-diagnostics, proceed to the TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

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