View Single Post
Old 08-03-2012, 03:42 AM   #885
mkodama
Registered User
 
mkodama's Avatar
 
Join Date: Oct 2006
Posts: 33,172
Successor to the carburetor, predecessor to mechanical fuel injection, Bosch K-Jetronic mechanical fuel injection system. When fitted with an engine driven fuel pump, can run without any electricity, and offered improvements in power, emissions, and mileage over a carburetor. Fitted to many sports cars that could afford the system, including Porsche, Ferrari, Mercedes-Benz, BMW, Audi, VW, Delorean, and others.

The downside, is that the system was entirely mechanical and relied on the precise dimension of many small parts, no debris or corrosion within the system, and the mechanical and chemical properties of all parts remaining the same. Designing something like this, is an entirely German engineering mindset, and is also horrible in terms of real life usage where parts will be exposed to unexpected temperatures, corrosion, and debris. Also, the system is immensely complex compared to electronic fuel injection, which in contrast only varies injector pulse duration to do the function of the many different devices.



This overly complex system is why my 190E doesn't run right. The KE-Jetronic of the 190E 2.3-16V differs from the video in a few ways, making it a few steps closer to EFI.
-Separate fuel pressure regulator with vacuum reference for system pressure(just like EFI).
-ECU controlled warmup valve which allows the ECU to adjust based on inputs from altitude sensors, coolant temperature sensors, and oxygen sensors, of which my 190E only has the coolant temperature sensor.
-ECU controlled idle control valve that eliminates the need for the auxiliary air valve (just like EFI).
-ECU controlled cold start valve, still with on-off function, eliminates thermo-time switch.

This system really makes me love how simple modern EFI is. When moving parts are kept to a minimum, reliability goes way up.
-Fuel injectors are the only fuel regulating devices.
-An electronic throttle body is the only air regulating device.
__________________

mkodama is offline