Design Team: Keith Parker
Supervisor: Prof. Roydon Fraser
Background
The University of Waterloo Alternative Fuels Team (UWAFT) participates annually in the Ethanol Vehicle Challenge sponsored by General Motors, the U.S. Department of Energy and National Resources Canada. The goal of this competition is to convert a 1999 Chevrolet Silverado 5.3L V8 pickup truck to run on Ethanol-85 and optimize its operation. The truck is scored against four main criteria: power output, the ability to perform cold starts, fuel economy, exhaust emissions.
In modern automobiles, electronic control systems are essential to optimum engine operation. Electronic control became popular in the 1970's when government regulations became stricter on automobile emissions and fuel economy. Today, electronic control is enabling cars in California to meet the stringent California Ultra Low Emissions Vehicle (ULEV) standards.
Since proper control of engine operation is important in meeting emissions, fuel economy, power output and cold starting standards, the teams competing in the Ethanol Vehicle Challenge have been provided with technical information and support from General Motors to modify the Powertrain Control Module (PCM). The PCM is the main controller in the Silverado.
Project description
Problem statement: To improve the performance of the UWAFT Silverado Pickup truck in the areas of power output, cold start and driveability, fuel economy and exhaust emissions through adjustments made to the powertrain control module.
Ethanol has different properties that standard gasoline in that it burns differently and with less power than gasoline. As such, an engine optimized for gasoline as its fuel will not operate as efficiently. Some of the factors influencing operation include spark timing, amount of fuel to inject, amount of exhaust gas recirculation and the idle speed. These are all factors that can be controlled through the PCM.
The objectives of this project are to improve in each of the following areas over last year's competition results through the reprogramming of the Powertrain Control Module.
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Improve the exhaust emissions
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Improve the cold start and driveability
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Improve the fuel economy
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Improve the output power
These objectives will be measured against last year's competition through tests that are similar to those performed at the competition. This testing is fairly rigorous and for some of the parameters it is the same standard testing done by govenment agencies in verifying the compliance of government standards.
Fuel economy and exhaust emissions will be tested through Environment Protection Agency's (EPA) Standard Federal Test Procedure, the Urban Dynamometer Driving Schedule and the Highway Fuel Economy Test. on-road fuel economy can also be measured. Cold start testing is done by testing the time it takes to start the truck under cold conditions (less that 0 degrees F) and by testing the emissions released. Cold start also considers the driveability after a cold start through simply driving the truck to see if there are any stalls or hesitations. Finally, the output power will be tested against performance in the Standing Quarter Mile Drag and via Dynamometer testing.
Design methodology
The approach to be taken is an iterative approach to first understanding the nature of the problem, understanding the science and principals involved, and addressing the problem with an overall systems approach. The solution will be work towards one parameter at a time, iteratively improving the engine optimization, and testing at each step.
The more specific details are as follows:
The first step is to understand what parameters are available for calibration, and the effects any modifications to those parameters will have.
The second step is to identify the parameters that yield the best opportunity to improve the engine operation against the objectives.
The third step is to determine the best method of analysis for each parameter of interest. The calibration of some parameters is so complex that the only way to improve them will be to make iterative modifications and examine the results. Others are very simple that one calculation can determine the optimum value.
The fourth step is to prioritize the parameters of focus. For example, if the current cold start strategy is changed, then more effort may be required in benefiting from parameters that affect cold starting.
Finally, tests and PCM updates will be done weekly. Due to the difference between the theoretical (calculated) improvements, and the real world results, there will need to be a significant amount of testing done. This will require PCM updates as often as possible in order to iterate towards the optimum calibration.