There are 3 basic test combinations recommended at this time to speed analysis with the FirstLook sensor. First is a Base cylinder efficiency test combination. This can be done by using the Exhaust - Triggered Engine Cranking Test and the Vacuum - Triggered Engine Cranking Test. Second would be a Running Cylinder Contribution test combination. This should be done using the Exhaust - Triggered Engine Idling Test and Injector Analysis from the Regulator test. Last would be an Intermittent Test combination. This can be done using the Exhaust - Triggered Engine Idling Test and Injector Analysis from the Regulator.
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Base Cylinder Efficiency
When running this test sequence you can verify the base condition of the engine. These tests allow us to look at the action of the valve train and cylinders; exhaust valves through the Exhaust - Triggered Engine Cranking Test and intake valves through the vacuum port using the Vacuum - Triggered Engine Cranking Test. Also if the same cylinder fails both the intake and exhaust tests you can speculate either a cracked head between valves or a problem with the piston or rings. If any problems are found with these test, you know which is the deficient cylinder and can continue with other diagnosis on that cylinder alone. This becomes very helpful as it is increasingly difficult to get to plugs in modern engines.
Running Cylinder Contribution
If the base engine functions are in proper working order and are not a contributing factor we can now do the run sequences. The Exhaust - Triggered Engine Idling Test quickly determines which cylinders are contributing to the overall performance of the engine. As you review the individual test procedures and the waveform analysis sections you can see that non contribution by a cylinder becomes very evident with a dropout followed by a compensation curve of the waveform. As with any tool the more you use the tool the easier it becomes to pick out faults. The Injector Analysis from the Regulator gives us a unique view of the injector function, in sequentially injected engines. This test allows the viewing of the individual injectors as they discharge fuel in to the specific cylinders, also showing the recovery back to base fuel pressure. This becomes a fast and easy way to diagnose injector failure, through viewing their contribution to total engine function.
Intermittent
The most challenging and time consuming job in diagnosis is intermittent testing. Because the FirstLook sensor is looking at unprocessed data, it can help you pickup these failures more quickly. If we expand the time base on the scope we can see cylinder related failures that are not consistent enough to be tracked in other ways. In some cases it can be seen right on the Exhaust - Triggered Engine Idling Test as an event that occurs at idle. Also the Injector Analysis from the Regulator can be used to track failure to a single injector circuit. Always remember there is more in the injector circuit than just the injector, often the driver circuit is damaged when an injector fails. Watching an intermittent failure by this method allows us to eliminate possible causes quickly, and move more efficiently to a proper diagnosis and ultimately a repaired vehicle.
