Engine Controls - Remove/install/overhaul: Other BMW 5 series E34

Direct Ignition System (DIS)

1. Ignition switch must ALWAYS be turned off before working on the ignition system. The engine may not be started without a connected secondary circuit. When checking compression, the DME master relay must be removed.
2. Shielded capacitors may not be connected to terminal No. 1 of the ignition coil. Terminal No. 1 of the ignition coil may not be connected to ground or battery positive terminal, as this will damage ignition stages in DME control unit.
3. DO NOT connect DVOM or test light to terminal No. 1 of ignition coil while engine is running. High tension (350 volts) is present at coil terminal No. 4, secondary ignition leads, spark plugs and ignition coil terminal No. 1 to DME control unit.

Note. For location of DME master and fuel pump relays, see DME & FUEL PUMP RELAY LOCATION table under FUEL SYSTEM PRESSURE RELEASE under FUEL SYSTEM.

CRANKSHAFT SENSOR (325i, 325iC, 325is & 525i)

Locate sensor connector near engine oil level dipstick. Remove screws and crankshaft pulley cover. Locate sensor on right side of crankshaft, and remove bolt and sensor. To install, reverse removal procedure.

CYLINDER IDENTIFYING SENSOR (325i, 325iC, 325is & 525i)

Locate sensor connector near engine oil level dipstick. Locate sensor on font left side of engine. Remove bolt and sensor. To install, reverse removal pro-cedure.

IGNITION COIL (325i, 325iC, 325is & 525i)

1. Remove oil filler cap. Remove 2 nut covers and nuts securing cylinder head cover. Remove cylinder head cover. Disconnect ignition coil connector. Remove 2 nuts and pull out ignition coil.
2. To install, reverse removal procedure. Ground straps of cylinder head cover must be secured to ignition coils for cylinders No. 3 and 6. Ensure that ignition coil common ground lead is attached to front of cylinder head, near engine lift bracket.

FUEL SYSTEM

FUEL SYSTEM PRESSURE RELEASE

Fuel system pressure release procedure not available from manufacturer. It may be possible to remove fuel pump relay, start engine, and run engine until fuel pressure drops (engine stalls). See DME & FUEL PUMP RELAY LOCATION table.

DME & FUEL PUMP RELAY LOCATION

Scheme 1

AIR MASS SENSOR (325i, 325iC, 325is & 525i)

1. Turn coupling and disconnect air mass sensor connector. Loosen hose clamp and pull off bellows.
2. Loosen screws or open fasteners at air cleaner assembly. Remove air mass sensor and bellows. To install, reverse removal procedure. Ensure that air mass sensor grille is not damaged during installation.

FUEL PUMP (325i, 325iC & 325is)

1. Pull up rear seat cushion and remove insulation sheet. Siphon out as much fuel as possible from fuel tank and store fuel in approved gasoline container.
2. Remove fuel pump access cover(s). Mark evaporative system/fuel hoses for installation reference and remove hoses. Disconnect fuel pump connector. Using Wrench (16-1-020), loosen ring and remove fuel pump/fuel gauge sending unit. To install, reverse removal pro-cedure.

FUEL PUMP (525i)

1. Siphon out as much fuel as possible from fuel tank, as fuel pump is secured to bottom of tank. Store fuel in approved gasoline container. Remove trunk trim panels. Remove 5 screws and fuel pump access cover.
2. Mark evaporative system/fuel hoses for installation reference and remove hoses. Pull connector slide to one side and disconnect fuel pump connector. Remove 8 screws, seal, and fuel gauge sending unit.
3. Compress safety clips and remove fuel pump from above. If necessary, remove pressure damper, check valve and fuel filter screen. Pull off pump holder. To install, reverse removal procedure.

FUEL PRESSURE REGULATOR (325i, 325iC, 325is & 525i)

1. On 325 Series, remove DME control unit cover from center of firewall. On all models, remove 2 nut covers and nuts securing cylinder head cover. Remove cylinder head cover. 2) Remove screws and fresh air housing (intake manifold cover). Remove fuel rail and injectors. Remove bolt from clamp securing fuel pressure regulator. Pull out fuel pressure regulator. To install, reverse removal procedure. Ensure retaining ring is installed in clamp.

FUEL RAIL & INJECTORS (325i, 325iC, 325is & 525i)

1. On 325 Series, remove DME control unit cover from center of firewall. Pull off rubber strips along top edge of engine compartment firewall. Remove screws and wiring harness duct along engine compartment firewall.
2. On all models, remove 2 nut covers and nuts securing cylinder head cover. Remove cylinder head covers. Remove screws and fresh air housing (intake manifold cover).
3. Loosen hose clamp and disconnect fuel supply hose from fuel rail. Remove 2 bolts and pull connector plate off of fuel injectors. Remove 4 bolts and disconnect fuel rail. Pull up on fuel rail and injectors.
4. Remove retainer from top of fuel injector. Remove fuel injector(s). To install, reverse removal procedure. Coat injector "O" rings with petroleum jelly during installation.

IDLE SPEED ACTUATOR (325i, 325iC, 325is & 525i)

1. Loosen clamp at air intake duct bellows. Pull off idle speed hose and vacuum hose, and remove bellows. Disconnect heater hose and move away from idle speed control actuator.
2. Disconnect idle speed control actuator connector. Remove clip and pull out hose from idle speed control actuator. Pull off vacuum hose from intake manifold. Push idle speed control actuator through retaining strap and remove. To install, reverse removal procedure.

OXYGEN (O2) SENSOR (325i, 325iC, 325is & 525i)

Locate oxygen sensor connector on transmission carrier and remove from clip holder. Remove oxygen sensor. To install, reverse removal procedure. Coat threads with anti-seize compound and install. Tighten oxygen sensor to 40 ft. lbs. (55 N.m).

THROTTLE POSITION SENSOR (325 Series & 525i)

Remove throttle body assembly. Remove screws and throttle position switch. To install, reverse removal procedure. Throttle position switch is not adjustable.