On this page you will find photos and descriptions of various 320i components. Toward the bottom of the page are Fuel Injection System, Fuel Supply System drawings, AC, ignition wiring diagrams and other drawings, Tech-Tips and interesting items via direct links to large images. Feel free to suggest future photo's or text.
All BMW 320i's for the U.S. use Bosch K-Jetronic CIS fuel injection and most of the photo's are from my 1981 320i - sold a few years ago.
Here's a site on Bosch K-Jetronic worth readingAll BMW 320i's for the U.S. use Bosch K-Jetronic CIS fuel injection and most of the photo's are from my 1981 320i - sold a few years ago.
Here's an overview of the engine bay.
This is the Cold Start Injector. It gives extra fuel during starting and briefly when very cold.
This is the PCV T-fitting. Air gases from the crankcase is vented through these hoses. Make sure its a tight fit or put on clamps as shown here.
This is the Auxilary Air Valve. When the engine is cold it allows extra air to bypass the throttle plate. This in turn forces extra fuel to be introduced. It acts basically as a choke in the traditional sense.
This is the PCV T-fitting. Air gases from the crankcase is vented through these hoses. Make sure its a tight fit or put on clamps as shown here.
This is the Auxilary Air Valve. When the engine is cold it allows extra air to bypass the throttle plate. This in turn forces extra fuel to be introduced. It acts basically as a choke in the traditional sense.
This is the Fuel Distributor. The heart of the fuel system that provides fuel to the injectors. The Line Pressure unit is the hex shaped thing toward the right on the base of the distributor.
Here is one of four Fuel Injectors which are mounted on the cyl. head. They open at specific pressures rather then electronically.
This is the Thermo Time Switch. At specific cold tempuratures in tells the cold start valve to activate.
This is the Warm-up Regulator. Its allows extra fuel to flow when the engine is cold. Inside the unit is an electrically heated steel rod which changes the flow rate of the unit. Its mounted under the starter area. Note: There is a tiny screen filter on the fuel inlet.
This is the Frequency Valve. Its mounted between the fuel distributor and the engine and under the air plenum. Very difficult to see when in place. Not 100% certain what it does but here goes. The valve is electrically controlled by the fuel injection computer based on readings from the oxygen sensor. The rigid line goes to the fuel distributor and the outlet with larger plastic hose connects with the fuel return hose to send excess fuel to the tank. Basically it richens/leans the mixture by controling the pressure within the fuel distributor. 
This is the access hole under the back seat for the fuel tank sender/pickup/booster pump. Hoses here are often soft and weeping fuel. There are electrical connections for the booster pump (small plug) and the fuel level sender (large plug).
This is the Fuel Tank Pickup. It has a screen filter at the bottom, a booster fuel pump, and fuel level sender.
This is the Left Fuel Tank. I had to remove it to replace the upper vent hose to stop a fuel leak when the tank was full.
In this photo I am testing the fuel pressure. I connected a T-fitting on the outlet of the fuel filter at the back of the car. Pressure should be better than 71psi.
Here is the Ignition Distributor and Coil behind it.
The Ignition Module. Part of the point-less ignition system. See schematic drawings toward the bottom too!
The Fuse and Relay Box in the engine bay.
This is the Brake Master Cylinder and Reservoir.
Injection System donor cars: Any car running K-Jetronic CIS could be a good donor for a 320i. The only thing I can think of is the injectors themselves may be metered differently depending on the displacement of the donor and the fuel distributor on 6 and 8 cyl models. Many VW's have most of the system high up in the engine bay which makes getting parts a lot easier than from a donor 320.
According to a Fuel injection manual I have the following cars used Bosch K-Jetronic:
Audi, 100LS 76-77, Fox 76-79, 4000 & coupe 80-on, 5000 & Turbo & Quattro 78-on
BMW 320i 77-83
Mercedes Benz 280E & SE & CE 77-81, 450SL SLC SE SEL 76-80, 6.9 78-79, 380SL SLC SEL SEC 81-on
Peugeot 505 80-on
Porsche 911SC 76-77, 911Turbo 78-83, 912E 76-79, 924 76-81, 928 78-79
Saab 99 76-78, 99 Turbo 78, 900 & Turbo 79-on
Volkswagen Dasher 76-81, Jetta 80-on, Rabbit 77-on, Scirroco 76-on, Quantum 82-on
Book is from 1983 so when years are listed as '-on' assume at least 1983 and possibly onward.
Here's a great site on Bosch K-Jetronic worth reading
Injection System donor cars: Any car running K-Jetronic CIS could be a good donor for a 320i. The only thing I can think of is the injectors themselves may be metered differently depending on the displacement of the donor and the fuel distributor on 6 and 8 cyl models. Many VW's have most of the system high up in the engine bay which makes getting parts a lot easier than from a donor 320.
According to a Fuel injection manual I have the following cars used Bosch K-Jetronic:
Audi, 100LS 76-77, Fox 76-79, 4000 & coupe 80-on, 5000 & Turbo & Quattro 78-on
BMW 320i 77-83
Mercedes Benz 280E & SE & CE 77-81, 450SL SLC SE SEL 76-80, 6.9 78-79, 380SL SLC SEL SEC 81-on
Peugeot 505 80-on
Porsche 911SC 76-77, 911Turbo 78-83, 912E 76-79, 924 76-81, 928 78-79
Saab 99 76-78, 99 Turbo 78, 900 & Turbo 79-on
Volkswagen Dasher 76-81, Jetta 80-on, Rabbit 77-on, Scirroco 76-on, Quantum 82-on
Book is from 1983 so when years are listed as '-on' assume at least 1983 and possibly onward.
Here's a great site on Bosch K-Jetronic worth reading
Now I'll detail some of the components of the Air Conditioning system. Here is the Compressor Pump. This is a Bosch unit while most had York.
Here is the AC Evaporator and blower assembly which would be installed in the dash.
Inside the evaporator is the Expansion Valve. Few people will ever see this in person fortunately.
This is the Condensor which is mounted in front of the radiator. 
source: www.lexam.net