Oscilloscope Patterns to Capture WS3A

Oxygen sensor.

Its a sensor that adjust air to fuel ratio when engine in a closed loop. It riches and leans fuel mixture by opening injectors longer or shorter.

This is a cycle of oxygen sensor, when engine on idle and in closed loop it cycles to make emission less, so we can breath fresh air. If this sensor is old, it can be blocked by exhaust gases and give wrong reading and make the car run rich when it should be lean. Also if wires are corrupted with oxidation, it also can give a wrong signal, if we add extra resistance in the plug of the sensor it will affect the output signal of the sensor. So the ECU can always think that its running lean and add extra fuel and make the engine run inefficient by using extra petrol, even black smoke can be visible from exhaust if its so bad.

This is Toyota idle control valve, Regulates idle depending on engine temperature, problem when siezed up ether on cold start -high idle or cold start hot idle. Can be cleaned and work back as factory. If it seized up when its in hot mode it will have high RPM's even when engine fully warmed up above 1200 RPM's constantly, or when its stuck in warm position, the car wont have cold start idle. So this thing helps to get engine to warm up or closed loop mode faster by adding more air on idle. When this vale malfunction it will take longer time on idle to get to closed loop, so emission would be increased.

Fuel injector. This thing supply engine with fuel (petrol or diesel). It remains closed and opens only when fuel needs to be injected, fuel keeps under pressure in the fuel line. Could cause problem when starts dripping fuel or high resistance created in trigger (ground wire) by opening them for shorter period. May cause bad performance on high and low RPM's. They can be clean to give more performance when old, but needs to be replace as non fixable item.

Here is a MAP sensor or engine load sensor. Wave for on oscilloscope shows when engine accelerating wave going up increasing voltage and decelerating wave going down voltage low, better then air flow meter as last longer. It has got 5 volts supply, ground and signal output for ECU. Ef any of wires got high resistance it will effect the sensor output and make the engine runs bad.

TPS sensor. On a graph we can see switch type. Down the bottom of the graph is a 0 volts and when it fully open it read about 12 volts and give ECU signal to spray more fuel as car in fast acceleration mode. For automatic car it also will change gear to the lowest possible one.

Air flow meter, that the sensor which can kill your engine or ether run it properly! On a graph we can see when throttle open and more air gets inside intake manifold it changes voltage output straight away and from 0.2 volts it reads above 4 volts. How does it happened? Magic or something else? It hag got platinum wire and a thermistor wire connected to OP-AM with a Winston bridge. Op-am looks at the signal output and multiples it for ECU to read. With the output signal ECU can determine how much petrol to inject for better combustion and fuel economy. If we increase resistance in platinum wire lets say because of oxidation, it will effect the out put signal and instead of running normal engine can run rich and use more fuel and produce more emission. So this sensor is critical for fuel economy and good performance as running rich doesn't mean running good!

CMP sensor, the car wont have a spark without this sensor and wont even start. Its important for ECU to know at which stroke number 1 cylinder and the rest 3 cylinders.