Editing Cadillac engine knowledge (section)
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===EFI=== [[File:Cad efi.jpg|left|400px]] <br style="clear:both"/> The factory EFI system used from 1975-'76 on 500 cubic inch engines is a port injection system which operates similar to the familiar Chevy TPI. It is a throttle body centered on an intake manifold with separate fuel injectors, and resembles the EFI set-up used on NASCAR Sprint Cup cars ca. 2012. Each cylinder has its own injector mounted in the intake runner near the intake gasket area with a common fuel rail feeding all eight injectors. This system was also used through 1979 on the Seville 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 delivery system consists of two fuel pumps (one in the tank, one mounted to the chassis), the fuel filter, the fuel pressure 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 two main groups, one for cylinders 1, 2, 7, and 8 and the other group for injectors cylinders 3, 4, 5, and 6. All four injectors in each group open simultaneously, with the two groups alternating in operation. The air distribution system consists of the throttle body assembly, the air filter 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 (Manifold Absolute Pressure) *TPS (Throttle Position Sensor) *MAT (Manifold Air Temperature) *CTS (Coolant Temperature Sensor) *Engine Speed Sensor (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 engine speed 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 four 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 stock EFI is not very good for performance applications, it does not keep up with aftermarket cams. You need to change the fuel injectors for high flow ones, and use a fuel pump with a return line. The stock EFI will only handle approximately 300 hp max, they're hard to find replacement parts for. There were more Cadillacs made with the 800 cfm Q-jet than with EFI. And what's worse is the EFI equipped engines didn't make much more hp then the carbed versions.
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