GM 55577403 Direct Fuel Injector Assembly

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For 2015 and earlier models, start by disconnecting the negative battery terminal and removing the engine cover if present. Relieve the fuel system pressure, then proceed to remove the air intake duct and air filter housing. Release the quick-connect fuel line fitting at the fuel rail, disconnect the EVAP purge line from the intake manifold, and unclip the electrical connectors from the fuel injectors and the MAP sensor. Remove the fuel rail mounting bolts and, if equipped, the ground strap. Remove the fuel rail and injectors as a single assembly, ensuring there are no O-rings left inside the injector holes. Remove the retainer securing each injector to the fuel rail and pull out the injectors. Replace the old O-rings on each injector with new ones before reassembly. Lubricate the new injector O-rings with clean engine oil during installation and tighten the fuel rail mounting bolts. Start the engine and check for fuel leaks. For 2016 and later models, relieve the fuel system pressure and disconnect the negative battery remote terminal. Remove the oil filler cap and engine cover fasteners, then lift the engine cover and valve cover insulator, reinstalling the oil filler cap if needed. Remove the ignition coils and charge air cooler outlet hose. Disconnect the harness connectors from the fuel rail and the camshaft position sensor, moving the wiring harness out of the way. Remove the sound insulator around the high-pressure fuel pump body. Using a flare-nut wrench, unscrew the intermediate high-pressure line fittings between the fuel rail and fuel pump, then remove the fuel line bracket bolt. Loosen the encapsulated fuel rail-to-cylinder head bolts but do not attempt to remove them. Install special demounting screws and support tools for the injectors. Use slide hammers to gently tap the injectors upward evenly, ensuring they don't tilt or come out unevenly. Place the assembly on a workbench, remove the slide hammers, and secure it in a vise. Attach special calibration tools to the injectors and rotate them clockwise. To replace an injector, disconnect the fuel injector electrical connector and remove the support plate bolts, supports, and demounting screws for that specific injector. Remove the injector, replace its O-ring seal, and reinstall it into the fuel rail. Replace the Teflon combustion seals using a special fuel injector kit, remove the support plate, and one support assembly from each injector. Coat the new fuel injector mounting bolts with a non-hardening thread locking agent and install them. Ensure the injector bores in the cylinder head are clean. Remove the calibration tools from the ends of the injectors and carefully insert the injectors into the bores as the fuel rail assembly is lowered onto the engine. Push the injectors into their seats, start the mounting bolts, and tighten them hand-tight before tightening the fuel rail mounting bolts in sequence. Finally, complete the installation by reversing the removal steps and checking for fuel leaks once the engine is started.

To remove the SL engine, start by relieving the fuel system pressure and disconnecting the battery. Then, remove the engine cover, insulation, and ignition coils. Disconnect the fuel rail pressure sensor and individual injector connectors, and move the harness out of the way. Disconnect the fuel rail harness connector and the high-pressure fuel pipe. Remove the fuel injector assembly screws using either Method 1 or Method 2. Next, remove the injectors from the fuel rail by carefully prying the assembly apart and pulling the injectors away. For 2.0L and 2.5L engines, disconnect the high-pressure fuel pipe, remove the intake manifold, and disconnect the fuel rail harness and pressure sensor connectors. Remove the fuel rail mounting bolts and upper grommets, and disconnect the electrical connector from the fuel rail harness. Remove the bolts and work the fuel rail and injectors from the cylinder head. Disconnect the fuel injector electrical connectors and remove the injector harness. To service the injectors, remove the Teflon seal by cutting it from the injector. For Teflon seal installation, use a fuel injector service kit and wrap aluminum AC ducting tape around the lower injector seal groove. Install the seal onto the injector body using the injector service tool, remove the tape, and repeat the steps for the lower groove. Compress the seals using the correct diameter compression ring. Finally, install the injectors and fuel rail back into the cylinder head, tighten the bolts, and check for leaks before starting the engine.