Engine Controls - Adjustments: Other Mazda 626 GD

ENGINE COMPRESSION

1. Ensure battery is fully charged and engine is at normal operating temperature. Allow engine to cool for 10 minutes. Remove spark plugs and disconnect ignition coil primary connector.
2. Hold throttle valve fully open during test. Attach compression gauge and crank engine until maximum pressure is reached at each cylinder. See «COMPRESSION SPECIFICATIONS»(ref-18158-S20113941912000123000000) table. Lowest cylinder pressure should be at least 75 percent of highest cylinder pressure.

COMPRESSION PRESSURE SPECIFICATIONS

VALVE CLEARANCE

Note. All piston engines have Hydraulic Lash Adjusters (HLA). Valve adjustment is not required.

IGNITION TIMING

1. With engine at normal operating temperature, place in Neutral (M/T) or Park (A/T). Disconnect and plug vacuum advance hoses (if equipped).
2. On all except carbureted B2200, connect jumper wire between timing test connector and ground. (Scheme 1) Ensure idle speed is correct. Connect timing light and set timing as required. See «PISTON ENGINE IGNITION TIMING SPECIFICATIONS»(ref-18158-S01839216592000123000000) table. (Scheme 2)

Scheme 1

PISTON ENGINE IGNITION TIMING

Scheme 2

IDLE SPEED & MIXTURE

Note. Mixture adjustment is NOT a normal tune-up procedure. DO NOT adjust mixture unless mixture control unit is replaced or vehicle fails emissions test.

IDLE MIXTURE

Air/fuel mixture is computer controlled and there is no provision for manual adjustment. If CO level is excessive, visually inspect entire system. See BASIC TESTING article.

THROTTLE POSITION SENSOR (TPS)

Note. All procedures are performed with engine at normal operating temperature.

1. Remove throttle body air hose. Install test harness (49 G018 901) between TPS and harness. Turn ignition on. With throttle closed, measure TPS connector voltage at Red and Black wires. (Scheme 3)
2. Red wire should have 4.5-5.5 volts. Black wire should have zero volts. If voltage is incorrect, check battery voltage, wiring harness and connectors. If okay, see TESTS W/CODES and SYSTEM/COMP TESTS articles.
3. If voltage in step 2) was okay, record Red wire voltage. Measure voltage at Blue wire while slowly opening and closing throttle valve. (Scheme 3) See B2600i, MPV (4-CYL.), MX-6 & 626 TPS VOLTAGE table.
4. If voltage is not to specification, loosen TPS and rotate sensor until Blue wire voltage is correct. If TPS cannot be adjusted to specifications, replace TPS unit. When procedure is completed, remove negative battery cable and apply brake pedal for 5 seconds to erase control unit memory.

TPS VOLTAGE

Scheme 3