KE-Jetronic and Mercedes-Benz E-Class 300TE

Let me tell you a short story about what really KE-Jetronic is, just in case somebody doesn’t know it so far.

Cosworth DFV is a Lucas fuel injection system model.

In the 1970-s a relatively inexpensive and reliable fuel injection system has been invented. It provided greater petrol economy in comparison with carburetor and, in the same time, the price didn’t have to be way too high and unaffordable. Before that, such injection systems were installed only on aircrafts as well as on Formula-1 and Grand Prix autos. The whole system was named K-Jetronic.

By the way, only two companies, Bosch and Lucas, have developed almost all of the various fuel injection systems. What is most interesting is that Lucas is more popular on the racing vehicles while Bosch has developed those very first injection systems for diesel engines. The latter, by the way, were used in the T-34 tank engines in the 1930-s.

But that is a whole different story. Also, Bosch has developed first mass mechanical injection systems ever as well as the very fist electronic ones.

Basically, K-Jetronic – Bosch CIS (Continuous Injection System) – is well known all around the world as a mechanical injection system that supplies fuel continuously to each of the 4 or 6 jet nozzles (or how many of them does your engine system have). The system has been used on a wide variety of cars – Ferrari, Lamborghini, Porsche, Mercedes, Volkswagen, Audi, Volvo etc. up until 1985 or so.


Various electronic injection systems have become more widespread in the 1980-s – Bosch L-Jectronic, for instance. Such injection systems are also installed in the modern autos (hello, Toyota!). But the Mercedes Company had decided to leave it all to Japan and started working closely with Bosch closely to improve, upgrade, and modernize the system for it to meet higher standards.


Or let’s have a look at one more version – Bosch CIS-E (Continuous Injection System – Electronic). It is a so-called hybrid – a mixture of mechanical and electronic injection systems. Basically, it is pretty similar to the K-Jetronic with some changes and modifications.

In particular, an air meter has been added (it counts all the air that passes to the injection system itself), engine control unit (basically the “brain” of the whole system), electric hydraulic mixture controller, accelerators, catalysts, and the lambda probe. The mixture parameters are set up in the “brain” and are being modified (if needed) thanks to the lambda probe which was a pretty new invention in the 1980-s. Its primary task is to detect the amount of oxygen in the exhaustion. The computer itself defines the correlation between the air and the fuel itself in the mixture based on the air meter data. Also it takes into consideration the unburned oxygen amount and corrects the mixture by means of the electric hydraulic mixture controller.

The disadvantages of KE-Jetronic are as follows. It requires professional service, although not so many people do know how to deal with the whole system. For example, in case of a critical meter unit failure (the pipes there are not wider than your pinky finger) the engine can break down because of the fuel hydraulic impact (so-called water-hammer effect). I have seen such examples already.

The advantages of KE-Jetronic include the following issues. The system is sparing in comparison to carburetor, in case all the required service is provided. The injection system never lacks nozzles – you can modify and tune it the way you want if you do know how to set it up.

There are no further advantages, as I may consider. I supposed, that this injection system should require less service than the electronic one, but it all appeared to be the other way. A lot of people treat this injection system as a time tribute. Unfortunately, there is nothing so modern in the system itself.

It’t a good idea to use carburetors and electronic injectors instead, as I see it.

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