Download диагностика на всички запалителни

mScope
DIAGNOSIS OF ALL IGNITION
SYSYTEMS WITH MECHANICAL DISTRIBUTOR
Diagnosis of Primary ignition
To perform diagnostics of Primary ignition circuit, it is necessary to monitor waveform of
voltage or current of the primary winding of ignition coil. For this purpose at the entrance of
mScope must be used attenuator 20:1. Then the probe of the oscilloscope must be connected
to the primary winding of ignition coil.
If you have a Current clamp (CA-60), the shape and size of current can be measured through
the primary winding of the ignition coil.
Diagnosis of Secondary Ignition
To perform diagnostics of Secondary Ignition system you must have a capacitive pick-up
used to monitor the signal shape and an inductive pick-up through which the oscilloscope can
be synchronized in the first cylinder. In the measurement of high voltage (HV) signal it is
mandatory to use capacitive pick-up. Otherwise there is a high risk of damage to the
oscilloscope input. The most common sensor indicating first cylinder is inductive pick-up.
Sensor for the first cylinder (inductive pick-up) must be clamped to a high voltage cable of
the first cylinder.
Capacitive pick-up is connected to Channel A of mScope and it’s clamped to a high voltage
cable that goes from the coil and enters the general input of the distributor.
Inductive pick-up is connected to the EXT input (External trigger) of the oscilloscope and it
is clamped to the high voltage cable on the first cylinder.
Diagnosis of DIS ignition system
(an ignition coil serves two spark plugs)
DIS – below this cut will be understood only the ignition with synchronous ignition with coils
with two terminals. (English: DIS, German: DFS - doppel funken spule - twin ignition coils).
Diagnosis of Primary ignition
To perform a diagnosis of primary voltage of DIS ignition system, it is necessary to monitor
the waveform of the charge of primary windings of the ignition coils through the insertion of
probes to the primary circuit of the ignition coils. At the inputs of mScope must be used
attenuators 20:1.
Power switch for blackouts in the primary winding can be combined into one unit with the
coil. Therefore, when such construction is impossible to carry out diagnostics of ignition
voltage in its primary.
If you have a Current clamp (CA-60), you can measure the shape and size of current through
primary winding of ignition coil.
www.autoditex.com
Diagnosis of Secondary Ignition
In the measurement of high-voltage signals it is mandatory to use capacitive pick-up probes.
Otherwise there is a high risk to damage to the oscilloscope input.
During diagnosis of DIS systems in secondary voltage is not necessary to use sensor for
synchronization in the first cylinder because in DIS it is known which channel of the
oscilloscope to which cylinder is attached.
Channel A and Channel B:
Capacitive pick-up 1: Connected to Channel A of the oscilloscope and clamped to high
voltage cable that plug out of the first cylinder’s spark plug.
Capacitive pick-up 2: Connected to Channel B of the oscilloscope and clamped to high
voltage cable, which come out from the spark plug of second cylinder.
Then in order to watch the other two cylinders the capacitive probes are moved as follows:
Capacitive pick-up 1: It is already connected to Channel A of the oscilloscope and clamped
to high voltage cable that plug out of third cylinder spark plug.
Capacitive pick-up 2: It’s already connected to Channel B of oscilloscope and clamped to
high voltage cable that plug out of the forth cylinder spark plug.
EXT input (External trigger) – In this measurement on this input of oscilloscope does not
include any probe. If you need to measure engine speed (RPM), then to this input is connected
inductive pick-up.
Diagnosis of Direct Ignition system
(english: Direct Ignition; german: EFS)
(Each spark with its own ignition coil)
Diagnosis of DI ignition system using the oscilloscope
Each spark plug is ignited by its own individual ignition system, consisting of a driver or
ECM and ignition coil.
In the diagnosis of DI systems on secondary voltage is not necessary to use sensor for
synchronization in the first cylinder because they know which channel of the oscilloscope to
which cylinder is attached. You can use the inductive pick-up, which is connected to the EXT
input, if you need to measure engine RPM.
Channel A and Channel B:
Capacitive pick-up 1: It is connected to Channel A of the oscilloscope and clamped to high
voltage cable that plug out of a spark plug of random cylinder.
Capacitive pick-up 2: It is connected to Channel B of oscilloscope and clamped to high
voltage cable which comes out of a spark plug of random cylinder.
Then in order to watch the other two cylinders the capacitive probes must be moved.
www.autoditex.com
EXT input (External trigger) – In this measurements to this input of the oscilloscope no
probe is connected. You can use the inductive pick-up, which is connected to the EXT input,
if you need to measure the engine speed (RPM).
The Elements Of The Secondary Ignition Pattern
These parameters are practically the same for all varieties ignition systems.
It is very important to understand each part of the ignition coil waveform and what
went into making the amplitude or voltage change over time. Without an in-depth
understanding of the waveform, you will not know what has failed. For a proper
diagnosis of this waveform one must pay close attention to the smallest changes.
 Angle of closed state of contacts - (dwell angle or dwell period)
This is the angle on which the crankshaft rotates from the beginning of
accumulation of energy in the primary winding of the ignition coil until occurring of
the spark in the spark plug.
In ignition systems with mechanical switch, these are the degrees to which the
crankshaft is rotated from the moment of closing the contacts of the breaker until
they open again.
In ignition systems without mechanical switch, this is the time during which the
ECU allows to current to flow through the primary winding of ignition coil. The
beginning of the current flow is determined from the opening electronic powerful
switch and in the end of the current flow and hence the appearance of the spark is
determined by the time of obstruction of electronic powerful switch.
Dwell time is the length of time the coil primary circuit is being completed, and
current is flowing through it. The initial oscillations in the pattern are the result of
the initial build up of the magnetic field that is created around any conductor with
current passing. As that magnetic field builds in strength, it causes a "Counter
Electromotive Force" that opposes the current flow. This is why the pattern starts
to take a slight upward slope.
 Advance angle
This is angle on which the crankshaft is rotating at the moment when the spark
arises until reaching the relevant cylinder at the top dead center. One of main
tasks of any ignition system is to ensure optimum angle of advance in case of a
spark. To ensure maximum power, the mixture must be ignited before the piston,
which is in pumping cycle to reach its top dead center - so after reaching the top
dead gases can have a maximum pressure and maximum useful work carried out
during the working stroke of the piston. Also any ignition system provides
interrelationship between the angle of the advance of spark, engine speed and
engine load. When a spark uprise at a time that does not correspond to the
optimum advance angle deteriorates the engine performance and increases fuel
consumption.
www.autoditex.com
At higher speeds, the speed of movement of the pistons is increased at this time to
burn the mixture does not change - so the spark must occur earlier. Therefore the
advance must be increased.
At the same speed of the crankshaft, the throttle position (throttle) may vary. This
means that the cylinder will form a mixture of different composition and burning
rate of the mixture depends on its composition. At fully open throttle (fully
depressed accelerator pedal) the mixture burns faster and should be lit later - thus,
when the engine load is increased, you must reduce the advance. Conversely,
when the throttle is not tightly closed, the burning rate of the working mixture is
less, so you need to increase the advance.
 Drilling voltage - Firing Line
This is the value of voltage in the secondary circuit at the time of appearance of
the spark. In fact this is the maximum voltage in the secondary circuit. It directly
depends on the distance between the electrodes of spark plugs and the mixture in
the cylinders. A spark incurred at the time, which interrupts the current flow
through the primary winding of the ignition coil. Typical value of this tension is
between 7 kV and12 kV.
 Voltage combustion of the mixture - "spark Kv"
The point when the actual spark across the gap starts to take place. This part of
the pattern is called "spark Kv", or the energy required to actually initiate the spark
and keep it going. Spark Kv is affected by the actual resistance of the secondary
circuit, from the ignition wire, through the plug, across the gap to ground. High
spark Kv means higher than normal resistance, and lower spark Kv means lower
than normal resistance. Tensions in the secondary circuit of ignition during the
combustion of spark is usually between 1 kV-2 kV.
 Burn Time - spark line (called the spark duration)
The length of the combustion of spark. Normally is between 1.5 ms to 2 ms.
The "spark line" is the actual time the spark is moving across the plug gap.
Normally, this should be between 1.5 milliseconds to 2.0 milliseconds. Anything
under 0.8 milliseconds usually means that a misfire has occurred. It is affected by
the circuit resistance, just like spark Kv, but the neat thing about the burn line is
that it is a window into the combustion process.
All these parameters are shown in the chart below.
www.autoditex.com
www.autoditex.com