The wave forms below are taken from an EW10D, (HPI), direct petrol injection engine. They illustrate the 'upstream' Oxygen sensor, which is of the broadband type, in various stages of operation. It starts with initial start-up and progression through to normal operation, including engine speed increase.
The red wave is the current signal and the blue wave form is the reference voltage.
See how the reference voltage drops sharply then rises again, then starts to fall progressively.
During normal operation the voltage is stable at about 700mv.
See how the current wave increases it's frequency as the engine speed rises.
The wave form below shows both the front and rear oxygen sensors working correctly at 2000 rpm, no load. The sample is one of a 307 EW10 engine.
The Red wave is the front sensor, the Green is the rear sensor.
The following wave forms illustrate both the voltage signal and the current trace for an injector. This was sampled from an EW10 engine.
The current trace, (Blue wave), shows the, characteristic, step in the current, which is a result of the injector pintle lifting off it's seat.
The image below is that of a 'Trendplot' recording from the scopemeter. The fuel injector and pump supply, drops out intermittently, causing vehicle to stall. This is due to the 'double' relay failing. This fault did not flag a fault in the engine ECU.
The fuel injector signal below, taken from a vehicle with an injector misfire, illustrates the lack of induced peak voltage on the rising edge. This is due the solenoid windings being open circuit.
The wave form below shows the relationship between the throttle pedal sensor and the motorised throttle response. Taken from a TU5jp4. The blue wave is the throttle pedal.
The wave form below is a conventional view of the manifold absolute pressure sensor (MAP) taken from a TU3 engine. It shows the signal from idle to wide open throttle (WOT) and back to idle. This is a good signal.
The wave form shown below is that of a Air Mass meter, taken from an Audi A4. The signal shows the engine at idle to wide open throttle, (WOT), although not for very long. The signal doesn't reach it's maximum but does indicate a good reaction.
Last Reviewed: 11 April 2008Copyright © 2004...2009 Mark Stammers mark@peugeotmt.co.uk