Injector Replacement

Summer 2026

After modifying a 1998 BMW E36 by replacing pieces on the engine (replacing cams, intake manifold, and throttle body) to increase air flow, the engine began misfiring on several cylinders. Fuel injectors are small electronically controlled valves that spray gasoline into each cylinder. The original injectors could no longer provide the fuel the modified engine and tune required, causing inconsistent combustion. We replaced them with higher-flow injectors matched to the new setup, eliminating the misfires.

  • An image of the Float House.

    After the engine modifications were done to the car, the check-engine light came on and the engine would misfire. When I scanned the codes, I got a misfire in cylinder 3. Misfiring is when the ratio of spark, fuel, air, and compression in the cylinder is off. When this happens, the combustion inside the cylinders is irregular. Since I increased the airflow by adding the pieces mentioned previously, the injectors couldn’t provide enough gas to balance out the added air.

  • The fix included replacing the exiting injectors with higher-flow injectors. "Higher flow" means the new injectors would deliver more fuel more effectively. This picture shows the engine in the engine bay. The silver rail in the picture is the fuel rail. The injectors are face down going into the cylinder. The fuel rail delivers fuel to the injectors.

  • The electronic connectors connecting to the injectors are taken out. The electric connectors connect electricity to the injectors so that the DME (the engine control computer) can communicate with the injectors to tell the injectors how much fuel and when to release the fuel.

  • The injectors are now out but still connected to the fuel rail. The injectors are the metal cylinders sticking out of the fuel rail.

  • An image of The Float House.

    Here is a closer picture of the injectors. There is one injector per cylinder. This car has 6 cylinders, so it has 6 injectors.

  • An image of the Float House.

    In this picture the injectors are removed from the fuel rail.

  • This is a close-up of an injector. The top bit with the rubber grommet sticks into the fuel rail, and the port to upper right sticks into an electrical cable.

  • Another close-up of the injector. If you look closely, there are 4 little holes. The gas gets dispensed through those holes.

  • These are the old injectors outside of the car. The new injectors have blue tops while the old ones have green tops.

  • The new injectors are now in the car. After putting in these new injectors, the car ran perfectly! No misfiring and no check engine lights!