bosch
k.e. jetronic fuel injection
K.E.
JETRONIC FUEL INJECTION By Darren Parker Club Technical Advisor
As a
result of having some problems with poor starting and a bad misfire on the FORD RS Turbo engine
fitted to my Covin I have decided to include a
section to the site covering the Bosch K.E. Jetronic fuel injection system as
fitted to XR3, RS Turbo, VW, Porsche and many more fuel injection engines.
diagram
and components
the
problems I had with my k.e. jetronic fuel injection
The problem I had was as follows .... a bad
misfire resulting in very poor running and bad starting, very much like a
faulty spark plug or HT lead however after first changing the Distributor Cap,
Rotor Arm, Plugs and HT Leads the problem was still there..... All the plugs were firing but after the
engine was ran for a short time and the plugs inspected they were black in
colour and
very wet indicating rich mixture or poor compression..... The compression was
checked and found to be 140PSI which is fine for Turbo Charged engine (Lower
compression)..... The fault was obviously in the fuel system and my first thoughts were the
Thermo Time Switch was not opening after start up and causing the Cold Start
Valve to stay open injecting extra fuel into the inlet manifold ........ However
after testing the Thermo Time Switch with a meter it was found to be operating
correctly as was also the Cold Start Valve........ Next step was to remove all
the Fuel Injectors and test them by pushing down the Air Flow Sensor approx
1" then switching on the ignition with the Injectors in a clear vessel so
you can see the fuel spray pattern..... All injectors sprayed quite well apart
from No1 which no fuel came out at all....... I swapped No1 with No2 Injector and
tried again...... The result was the same nothing from No1 so I removed the
Injector pipe to Metering unit and checked it was clear, It was........ It was
becoming more obvious that the Fuel Distributor was at fault so I began disconnecting the various parts ready for removal and
inspection..... The last
part to disconnect was the air inlet pipe to the Turbo Charger and this had to be
done under the vehicle...... There was however a little surprise awaiting when I
removed the air inlet pipe from the Fuel Distributor to Turbo....... Approx 1/2
litre of petrol poured out of the lower air chamber on the Fuel Distributor and
Pipe...... This was the point where everything at once fell in to place.........
The problem was indeed the Fuel Distributor but now I knew what
was actually wrong with it.... Inside the Fuel Distributor are sealed chambers
that hold pressurized fuel ready to send to the injectors. When air enters the
engine, the airflow sensor plate lifts the control plunger and the fuel flows
from the lower chambers into the upper chambers. The pressure in the two
chambers equalize and the diaphragm deflects downward, opening the injector
valve orifice and allowing fuel to flow to the injectors but No1 chamber
had obviously broken down and was leaking fuel out to the air chamber and
not feeding the injector causing the Misfire on No1 cylinder and also the over
fueling of the remaining cylinders as they were not only getting fuel from their
injectors but also from a fuel/air mixture from the turbo air inlet thus causing
the plugs to foul up...... I sourced a second hand Fuel Distributor that had recently
been removed from a crash damaged RS Turbo and fitted it to my covin.....The
engine fired up instantly and ran at a smooth idle with good response to
throttle ......
This task of trouble shooting took me
many days to track down due to the complete LACK of information in the workshop
manuals..... About the only thing mentioned is that you must number the
Injector Lines when you remove them from the fuel distributor ????......Even
this information is incorrect as it makes no difference what line goes to what
Injector as they are all opened at the same time due to the fact KE Jetronic is
still basically Mechanical fuel injection with ECU included for Ignition timing
and fuel mixture.... So don't be afraid of what is actually a very simple type
of fuel injection with a plentiful supply of second hand parts available, better
fuel economy, cleaner emissions, smoother running and more reliable than Webber
twin 40's........ KEEP YOUR FUEL INJECTION ON YOUR ENGINE....................If
your not sure about something ask me darren@covin.co.uk
I might even know the answer..
k.e.
jetronic components and schematic
Components of the KE-Jetronic.
