Gasoline-engine management
Gasoline Fuel-Injection
System K-Jetronic
Technical Instruction
bmwe21.net
, Published by:
© Robert Bosch GmbH, 2000
Postfach 30 02 20,
D-70442 Stuttgart.
Automotive Equipment Business Sector,
Department for Automotive Services,
Technical Publications (KH/PDI2).
Editor-in-Chief:
Dipl.-Ing. (FH) Horst Bauer.
Editorial staff:
Dipl.-Ing. Karl-Heinz Dietsche,
Dipl.-Ing. (BA) Jürgen Crepin.
Presentation:
Dipl.-Ing. (FH) Ulrich Adler,
Joachim Kaiser,
Berthold Gauder, Leinfelden-Echterdingen.
Translation:
Peter Girling.
Technical graphics:
Bauer & Partner, Stuttgart.
Unless otherwise stated, the above are all
employees of Robert Bosch GmbH, Stuttgart.
Reproduction, copying, or translation of this
publication, including excerpts therefrom, is only to
ensue with our previous written consent and with
source credit.
Illustrations, descriptions, schematic diagrams,
and other data only serve for explanatory purposes
and for presentation of the text. They cannot be
used as the basis for design, installation, or scope
of delivery. We assume no liability for conformity of
the contents with national or local legal regulations.
We are exempt from liability.
We reserve the right to make changes at any time.
Printed in Germany.
Imprimé en Allemagne.
4th Edition, February 2000.
English translation of the German edition dated:
September 1998.
bmwe21.net
, K-Jetronic
Since its introduction, the K-Jetronic Combustion in the gasoline engine
gasoline-injection system has pro- The spark-ignition or
ved itself in millions of vehicles. Otto-cycle engine 2
This development was a direct result Gasoline-engine management
of the advantages which are inherent Technical requirements 4
in the injection of gasoline with Cylinder charge 5
regard to demands for economy of Mixture formation 7
operation, high output power, and Gasoline-injection systems
last but not least improvements to Overview 10
the quality of the exhaust gases K-Jetronic
emitted by the vehicle. Whereas the System overview 13
call for higher engine output was the Fuel supply 14
foremost consideration at the start of Fuel metering 18
the development work on gasoline Adapting to operating conditions 24
injection, today the target is to Supplementary functions 30
achieve higher fuel economy and Exhaust-gas treatment 32
lower toxic emissions. Electrical circuitry 36
Between the years 1973 and 1995, Workshop testing techniques 38
the highly reliable, mechanical multi-
point injection system K-Jetronic
was installed as Original Equipment
in series-production vehicles. Today,
it has been superseded by gasoline
injection systems which thanks to
electronics have been vastly im-
proved and expanded in their func-
tions. Since this point, the K-Jetronic
has now become particularly impor-
tant with regard to maintenance and
repair.
This manual will describe the
K-Jetronic’s function and its particu-
lar features.
bmwe21.net
, Combustion in
the gasoline
engine
Combustion in
the gasoline engine
combustion process pressurizes the
The spark-ignition cylinder, propelling the piston back down,
or Otto-cycle engine exerting force against the crankshaft and
performing work. After each combustion
stroke the spent gases are expelled from
Operating concept the cylinder in preparation for ingestion of
The spark-ignition or Otto-cycle1) a fresh charge of air/fuel mixture. The
powerplant is an internal-combustion (IC) primary design concept used to govern
engine that relies on an externally- this gas transfer in powerplants for
generated ignition spark to transform the automotive applications is the four-stroke
chemical energy contained in fuel into principle, with two crankshaft revolutions
kinetic energy. being required for each complete cycle.
Today’s standard spark-ignition engines
employ manifold injection for mixture
formation outside the combustion
The four-stroke principle
chamber. The mixture formation system The four-stroke engine employs flow-
produces an air/fuel mixture (based on control valves to govern gas transfer
gasoline or a gaseous fuel), which is (charge control). These valves open and
then drawn into the engine by the suction close the intake and exhaust tracts
generated as the pistons descend. The leading to and from the cylinder:
future will see increasing application of
systems that inject the fuel directly into the 1st stroke: Induction,
combustion chamber as an alternate 2nd stroke: Compression and ignition,
concept. As the piston rises, it compresses 3rd stroke: Combustion and work,
the mixture in preparation for the timed 4th stroke: Exhaust.
ignition process, in which externally-
generated energy initiates combustion via Induction stroke
the spark plug. The heat released in the Intake valve: open,
Fig. 1 Exhaust valve: closed,
Reciprocating piston-engine design concept Piston travel: downward,
OT = TDC (Top Dead Center); UT = BDC (Bottom Combustion: none.
Dead Center), Vh Swept volume, VC Compressed
volume, s Piston stroke. The piston’s downward motion increases
VC
OT the cylinder’s effective volume to draw
fresh air/fuel mixture through the passage
s exposed by the open intake valve.
Vh
UT Compression stroke
Intake valve: closed,
Exhaust valve: closed,
OT Piston travel: upward,
Combustion: initial ignition phase.
UMM0001E
1) After Nikolaus August Otto (1832 –1891), who
UT unveiled the first four-stroke gas-compression engine
2 at the Paris World Exhibition in 1876.
bmwe21.net
Gasoline Fuel-Injection
System K-Jetronic
Technical Instruction
bmwe21.net
, Published by:
© Robert Bosch GmbH, 2000
Postfach 30 02 20,
D-70442 Stuttgart.
Automotive Equipment Business Sector,
Department for Automotive Services,
Technical Publications (KH/PDI2).
Editor-in-Chief:
Dipl.-Ing. (FH) Horst Bauer.
Editorial staff:
Dipl.-Ing. Karl-Heinz Dietsche,
Dipl.-Ing. (BA) Jürgen Crepin.
Presentation:
Dipl.-Ing. (FH) Ulrich Adler,
Joachim Kaiser,
Berthold Gauder, Leinfelden-Echterdingen.
Translation:
Peter Girling.
Technical graphics:
Bauer & Partner, Stuttgart.
Unless otherwise stated, the above are all
employees of Robert Bosch GmbH, Stuttgart.
Reproduction, copying, or translation of this
publication, including excerpts therefrom, is only to
ensue with our previous written consent and with
source credit.
Illustrations, descriptions, schematic diagrams,
and other data only serve for explanatory purposes
and for presentation of the text. They cannot be
used as the basis for design, installation, or scope
of delivery. We assume no liability for conformity of
the contents with national or local legal regulations.
We are exempt from liability.
We reserve the right to make changes at any time.
Printed in Germany.
Imprimé en Allemagne.
4th Edition, February 2000.
English translation of the German edition dated:
September 1998.
bmwe21.net
, K-Jetronic
Since its introduction, the K-Jetronic Combustion in the gasoline engine
gasoline-injection system has pro- The spark-ignition or
ved itself in millions of vehicles. Otto-cycle engine 2
This development was a direct result Gasoline-engine management
of the advantages which are inherent Technical requirements 4
in the injection of gasoline with Cylinder charge 5
regard to demands for economy of Mixture formation 7
operation, high output power, and Gasoline-injection systems
last but not least improvements to Overview 10
the quality of the exhaust gases K-Jetronic
emitted by the vehicle. Whereas the System overview 13
call for higher engine output was the Fuel supply 14
foremost consideration at the start of Fuel metering 18
the development work on gasoline Adapting to operating conditions 24
injection, today the target is to Supplementary functions 30
achieve higher fuel economy and Exhaust-gas treatment 32
lower toxic emissions. Electrical circuitry 36
Between the years 1973 and 1995, Workshop testing techniques 38
the highly reliable, mechanical multi-
point injection system K-Jetronic
was installed as Original Equipment
in series-production vehicles. Today,
it has been superseded by gasoline
injection systems which thanks to
electronics have been vastly im-
proved and expanded in their func-
tions. Since this point, the K-Jetronic
has now become particularly impor-
tant with regard to maintenance and
repair.
This manual will describe the
K-Jetronic’s function and its particu-
lar features.
bmwe21.net
, Combustion in
the gasoline
engine
Combustion in
the gasoline engine
combustion process pressurizes the
The spark-ignition cylinder, propelling the piston back down,
or Otto-cycle engine exerting force against the crankshaft and
performing work. After each combustion
stroke the spent gases are expelled from
Operating concept the cylinder in preparation for ingestion of
The spark-ignition or Otto-cycle1) a fresh charge of air/fuel mixture. The
powerplant is an internal-combustion (IC) primary design concept used to govern
engine that relies on an externally- this gas transfer in powerplants for
generated ignition spark to transform the automotive applications is the four-stroke
chemical energy contained in fuel into principle, with two crankshaft revolutions
kinetic energy. being required for each complete cycle.
Today’s standard spark-ignition engines
employ manifold injection for mixture
formation outside the combustion
The four-stroke principle
chamber. The mixture formation system The four-stroke engine employs flow-
produces an air/fuel mixture (based on control valves to govern gas transfer
gasoline or a gaseous fuel), which is (charge control). These valves open and
then drawn into the engine by the suction close the intake and exhaust tracts
generated as the pistons descend. The leading to and from the cylinder:
future will see increasing application of
systems that inject the fuel directly into the 1st stroke: Induction,
combustion chamber as an alternate 2nd stroke: Compression and ignition,
concept. As the piston rises, it compresses 3rd stroke: Combustion and work,
the mixture in preparation for the timed 4th stroke: Exhaust.
ignition process, in which externally-
generated energy initiates combustion via Induction stroke
the spark plug. The heat released in the Intake valve: open,
Fig. 1 Exhaust valve: closed,
Reciprocating piston-engine design concept Piston travel: downward,
OT = TDC (Top Dead Center); UT = BDC (Bottom Combustion: none.
Dead Center), Vh Swept volume, VC Compressed
volume, s Piston stroke. The piston’s downward motion increases
VC
OT the cylinder’s effective volume to draw
fresh air/fuel mixture through the passage
s exposed by the open intake valve.
Vh
UT Compression stroke
Intake valve: closed,
Exhaust valve: closed,
OT Piston travel: upward,
Combustion: initial ignition phase.
UMM0001E
1) After Nikolaus August Otto (1832 –1891), who
UT unveiled the first four-stroke gas-compression engine
2 at the Paris World Exhibition in 1876.
bmwe21.net
