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| On the pump, a good electronically fuel injected engine definitely struts its stuff. You’ll see why shortly. Here, the Westech crew has just fired up the mule 402, in preparation for the pull. Note the idle speed (it’s a steady 1,000 RPM). | |
 The “Lambda sensor” or exhaust gas oxygen sensor (EGO or O2), is the most critical sensor in an EFI package. The ECU uses the O2 sensor's input to balance the fuel mixture, leaning the mixture when the sensor reads rich and richening the mixture when the sensor reads lean. According to the experts, Lambda sensors produce a voltage signal that recognizes the amount of unburned oxygen in the exhaust. When hot (at approximately 480 degrees F.), the zirconium dioxide element in the sensor's tip produces a voltage that varies according to the amount of oxygen in the exhaust compared to the ambient oxygen level in the outside air. The greater the difference, the higher the sensor's output voltage. Sensor output ranges from 0.2 Volts to 0.8 Volts (the higher the number, the richer the mixture). A "stoichiometric" fuel mixture of 14.7 parts of air to 1 part of fuel gives an average reading of around 0.45 Volts. |
Another advantage of the aftermarket systems is the fact that much of the complexity crafted by Detroit for emissions reasons can be removed. The oxygen sensors found in the stock exhaust manifolds can be removed which in turn opens the path for the use of leaded race fuel. The same removal process applies to the knock sensor (which retards the ignition timing if the engine is detonating). Tie this in with the removal of "street" equipment such as the heater or air conditioning, power brake booster, ABS system, power steering pump, cruise control, windshield wipers-washers along with other non-essential hardware and the engine compartment in an EFI drag car almost approaches Spartan.
If that's starting to sound interesting, there's more: Typically, the ECU is programmed on the dyno first. At this stage, parameters such as idle speed, ignition timing, air-fuel ratio at each RPM "step", air-fuel ratio at W.O.T., converter stall speed, shift RPM and other factors are included in the programming (all accomplished with either a personal computer or a lap top). In practice, this programming job consumes less time than setting the valve lash. Once the engine is installed in the car, it can be further fine tuned with a few simple strokes of the keyboard. Making the system even more appealing is the fact that the ECU automatically takes into account variables such as altitude, air temperature and barometric pressure, and compensates for them accordingly. In other words, you don't have to waste time tuning the car for conditions. The ECU does it for you.
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