Cadillac engine knowledge

===EFI===

===EFI===

The factory EFI system used from '75-'76 on 500 cubic inch engines is a ported injection system which operates similarly to the familiar Chevy tuned port injection. It appears like a large throttle body on an intake with separate fuel injectors. Each cylinder has its own injector mounted in the intake runner near the intake gasket area with a common fuel rail feeding all 8. This system was also used through 1979 on Sevilles as standard equipment and as an option on full size cars. It consists of four main systems; the ECU, the fuel delivery system, the air distribution system, and the sensors which supply information to the ECU. The ECU is a pre-programmed computer that analyzes the sensor information and computes the exact fuel requirements based on that information. It supplies the proper amount of fuel by opening the injectors for a specific amount of time, which varies as the engine operating conditions change. The fuel system consists of 2 fuel pumps (1 in tank, 1 on chassis), the fuel filter, the fuel presure regulator, the fuel rails and lines, and the injectors. The fuel system runs with a pressure reading of 39 to 55-95 PSI. A relief valve protects the system from excessive fuel pressure. The fuel regulator maintains the pressure in the fuel rails at 39 PSI for proper injector operation. The injectors are divided into 2 main groups, one for cylinders 1, 2, 7, and 8 and the other group for injectors 3, 4, 5, and 6. All four injectors in each group open simultaneously, with the 2 groups alternating in operation. The air distribution system consists of the throttle body assembly and the intake manifold. The throttle body houses the fast idle valve and the idle bypass air passage. The fast idle valve allows extra air to bypass the throttle blades when the engine is cold and closes as it warms up. The warm idle is adjusted at the idle bypass air passage. The sensors are as follows...MAP(intake pressure), TPS(throttle position), MAT(air temp), CTS(coolant temp), and RPM (engine speed measured at distributor). The MAP sensor is housed in the ECU and a plastic vacuum line connects it to the throttle body. The TPS sensor is mounted on the throttle body and is controlled by throttle blade movement. The MAT and CTS sensors are completely interchangeable. The MAT is located on the intake manifold and the CTS is located on the passenger cylinder head water outlet. The RPM sensor is on the distributor shaft under the cap assembly and sends engine speed and fuel triggering information to the ECU. This system runs in open loop configuration without an oxygen sensor and is quite easy to transplant into any vehicle, as long as all the components are used. The ECU has a separate computer/engine wiring harness that is easily swapped from donor vehicle to the new vehicle with only 4 wires and one vacuum line needing to be hooked up to work properly. All of the servicing information can be found in Chilton's #8587 manual, which deals exclusively with Cadillacs from 1967 to 1989.

The factory EFI system used from '75-'76 on 500 cubic inch engines is a ported injection system which operates similarly to the familiar Chevy tuned port injection. It appears like a large throttle body on an intake with separate fuel injectors. Each cylinder has its own injector mounted in the intake runner near the intake gasket area with a common fuel rail feeding all 8. This system was also used through 1979 on Sevilles as standard equipment and as an option on full size cars. It consists of four main systems; the ECU, the fuel delivery system, the air distribution system, and the sensors which supply information to the ECU. The ECU is a pre-programmed computer that analyzes the sensor information and computes the exact fuel requirements based on that information. It supplies the proper amount of fuel by opening the injectors for a specific amount of time, which varies as the engine operating conditions change. The fuel system consists of 2 fuel pumps (1 in tank, 1 on chassis), the fuel filter, the fuel presure regulator, the fuel rails and lines, and the injectors. The fuel system runs with a pressure reading of 39 to 55-95 PSI. A relief valve protects the system from excessive fuel pressure. The fuel regulator maintains the pressure in the fuel rails at 39 PSI for proper injector operation. The injectors are divided into 2 main groups, one for cylinders 1, 2, 7, and 8 and the other group for injectors 3, 4, 5, and 6. All four injectors in each group open simultaneously, with the 2 groups alternating in operation. The air distribution system consists of the throttle body assembly and the intake manifold. The throttle body houses the fast idle valve and the idle bypass air passage. The fast idle valve allows extra air to bypass the throttle blades when the engine is cold and closes as it warms up. The warm idle is adjusted at the idle bypass air passage. The sensors are as follows...MAP(intake pressure), TPS(throttle position), MAT(air temp), CTS(coolant temp), and RPM (engine speed measured at distributor). The MAP sensor is housed in the ECU and a plastic vacuum line connects it to the throttle body. The TPS sensor is mounted on the throttle body and is controlled by throttle blade movement. The MAT and CTS sensors are completely interchangeable. The MAT is located on the intake manifold and the CTS is located on the passenger cylinder head water outlet. The RPM sensor is on the distributor shaft under the cap assembly and sends engine speed and fuel triggering information to the ECU. This system runs in open loop configuration without an oxygen sensor and is quite easy to transplant into any vehicle, as long as all the components are used. The ECU has a separate computer/engine wiring harness that is easily swapped from donor vehicle to the new vehicle with only 4 wires and one vacuum line needing to be hooked up to work properly. All of the servicing information can be found in Chilton's #8587 manual, which deals exclusively with Cadillacs from 1967 to 1989.

===Distributors===

===Distributors===