WS3B - Dual Trace

MAP against Injector

Signal Name	MAP VS Injector
Volt/Division/Range	2V(MAP) 20V(injector)
Time/Division/Range	5ms

The pattern:

The wave A show the MAP sensor show there is no vacuum changing when the engine run at same RPM. For this pattern, MAP voltage is about 1.8V, that means the engine is running at high RPM, and injection fire should be longer than idling. For this pattern, wave B( injector ) open time is about 2.6ms.

When accelerate, throttle open more and decrease the vacuum in the manifold, so the MAP sensor signal voltage increase and let ECU to know more air is coming in. So ECU longer the injector open period for inject more fuel.

That means MAP can effect to injector open time but injector open time can not effect to MAP signal.

RPM against Injector

Signal Name	RPM VS Injector
Volt/Division/Range	10V(RPM) 10V(injector)
Time/Division/Range	5ms

The pattern:

RPM sensor sense the engine RPM. When accelerate, the injector open time increase and gives more power,so the engine rpm increase, sensor signal frequency increase and gives the signal to ECU to adjust the ignition timing.

Oxygen sensor against Injector

Signal Name	O2 VS Injector
Volt/Division/Range	0.5V(O2) 10V(injector)
Time/Division/Range	50ms

The pattern:

This pattern show when accelerate, the injector open time increase, more air and more fuel mix together. The engine running lean at idle and O2 sensor only have 0.1V, when accelerate, the engine run richer until close loop, cause the engine load is high and more fuel is sprayed, the signal voltage raise up about 0.4V.

Ignition primary against Injector

Signal Name	Ignition primary VS Injector
Volt/Division/Range	20V(ignition) 10V(injector)
Time/Division/Range	10ms

The pattern:

The ignition after the injector opened are in the same cylinder. When accelerate, the injector open time increase and gives more power, so the engine rpm increase, sensor signal frequency increase and gives the signal to ECU to adjust the ignition timing.

Ignition primary voltage against Ignition primary current

Signal Name	Ignition primary voltage VS Ignition primary current
Volt/Division/Range	10V(voltage) 0.5v(current)
Time/Division/Range	10ms

The pattern:

The current clamp set to 20A(100mV/Amp). From the pattern, the maximum of current shows 0.45V, so the current should be 450mV / 100mV/Amp = 4.5A

The pattern shows when the ignition is dwell time, the primary coil connect to ground and make the close circuit, the current can go through the coil and built up the magnetic field. When the firing, the primary coil disconnect to ground and open the circuit, so no current in the circuit.