Injector sequence from Plug reference
As soon as valve closes injector fires. This means
injectors are 1 step to
right
of exhaust sequence.
4
5
6
1
2
3
4
•
Power Brake Test.
This test is used to determine problems of engine under a
simulated load. It is best to use 2 people to do this test, one
person to operate the car and the other person to run the scope.
Starting Scope Settings
1.
Set Scope to AC signal
2.
Voltage settings... +1 Volts to — 1 Volts
3.
Time bas e ... 200 ms
4.
Start engine and adjust voltage for best display of waveform.
5.
Put engine into gear and set brakes.
6.
Slowly accelerate engine to 1500 RPM.
7.
Freeze the screen to examine the pattern.
8.
Return engine to idle and put in Neutral.
9.
This test was run using #1 plug as trigger reference. The Cold
Crank test can be run with or without a trigger as a quick
reference to the basic condition of the engine. Using a hand
held scope it is easy to walk out the door and take a quick look
at an engine.
Red Arrows indicate #1 Plug Trigger
97 Honda Accord Power Brake
4
How do you find the #1 cylinder?
Tail pipe readings are offset from the trigger reference. This accounts for
the time elapsed between from ignition firing and exhaust valve opening.
You need to understand offset to properly locate a problem cylinder.
P O N T I A C 3 8 0 0 # 2 I N J E C T O R D I S A B L E D E X H A U S T A T I D L E
Vertical arrows indicate inductive trigger using cylinder #1 as reference.
This screen shot shows both the injectors and the exhaust at idle.
Firing order 1-2-3-4-5-6...Offset 5-6-1-2-3-4.
1.
Tail pipe readings are offset from the trigger reference. This
accounts for time from ignition firing to exhaust valve opening.
2.
From the start of your trigger point, offset the cylinders like this
3.
4 cylinder engines offset
1
pulse to the right.
4.
6 cylinder engines offset 2 pulses to the right
5.
8 cylinder engines offset 3 pulses to the right
6.
This Pontiac fire order is 1-2-3-4-5-6
7.
But with the offset it is read on the scope as 5-6-1-2-3-4
8.
To determine timing between exhaust or injector events
refer to the timing chart included with your FirstLook
Diagnostic Sensor.
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