Description
(1) petrol injector
"a" 2-way black connector
Make: BOSCH
The petrol injectors consist of 2 parts
- An electrical control part
- A fuel spraying part
Each petrol injector is commanded separately by the engine ECU
Role
The petrol injectors spray the fuel needed for the engine to work
Function
"A" rest phase
"B" injection phase
"C" fuel under high pressure
"b" petrol injector needle with magnetic armature
"c" coil
"d" fuel supply
"e" filter
"f" return spring
Petrol injector at rest
The force of the return spring holds the petrol injector needle on its seat: there is no injection of fuel
Control of the coil and start of injection
At each electric pulse the coil is excited and the magnetic armature of the petrol injector needle is attracted
The petrol injector needle lifts and the fuel under pressure is sprayed upstream of the valve seat
End of injection
The coil is no longer excited, the magnetic armature of the petrol injector needle is no longer subject to the magnetic field
The force of the return spring keeps the petrol injector needle firmly on its seat: the injection of fuel stops
NoteThe petrol injectors are controlled individually in the injection sequence (1-3-4-2) during the inlet phase (sequential injection)
Electrical features
"D" electrical current (amps)
"F" time
Petrol injector control current
- "E" increased initial current
- "G" closing of the petrol injector
- "H" holding current
- "J" initial current
The initial current exceeds the rating of the return spring exerted on the petrol injector needle to separate it from its seat
The initial phase starts with an increased initial current which serves to reduce the separation time of the petrol injector needle
The holding current serves to keep the petrol injector needle open: during this phase the amperage of the current can be reduced, as it is no longer necessary to exceed the rating of the return spring exerted on the petrol injector needle
The use of a chopped current is to reduce the loss by joules effect at the ECU as well as at the petrol injector
| designation | value |
|---|---|
| nominal voltage | 12 Volts |
| resistance (at 23 °C) | 1,5 ± 5% ohms |
| fuel supply pressure at idle | 50 bars |
| fuel supply pressure under full load at high engine speed (steady pressure) | 120 bars |
| maximum fuel supply pressure under full load at high engine speed (occasional pressure) | 140 bars |
| number of channels | allocation of channels of connector |
|---|---|
| 1 | supply of the coil 12 V |
| 2 | control of the petrol injector |
Programming/initialisation
Programming is necessary if the component is replaced