Race Engine Calibration for Optimal Performance e-Seminar with Ron Matthews
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The engine control module (ECM, or on-board computer) is the tool used to control the fuel injection rate, fuel injection timing, ignition timing, rate of exhaust gas recirculation (EGR), and other functions. The task of "programming" the ECM is much easier for a race engine than for a production engine because the calibration engineer does not need to be concerned about emissions: EGR, keeping the exhaust catalyst "happy", etc.
In this e-Seminar, Professor Ron Matthews provides a practical introduction to ECMs, including the uses for the various sensors. He discusses the specific methods used to incorporate the various sensor signals into the ECM's control systems for the fuel injection rate, fuel injection timing, and ignition timing. Background information includes an understanding of the desired air/fuel ratio and optimum ignition timing. While examples are tailored around the application of the ECM to Formula SAE race engines, this e-Seminar is useful for improving any engineer's understanding of the functions of the ECM for other types of race engines as well as production engines.
Based on the popular classroom seminar, this course offers four and a half hours of instruction divided into six modules; more than two hours of bonus material and software demonstrations; and a glossary of acronyms, accompanied by a handbook.
Major topics include:
- Basic Engine Theory
- State the relationships between engine performance parameters, such as torque and specific fuel consumption, and the four fundamental efficiencies
- Describe how changing a control parameter, such as the air/fuel ratio, affects performance via the effects of this control parameter on each of the fundamental efficiencies
- Describe how changing an operating condition (engine speed and load) affects performance via the effects of this operating condition on each of the fundamental efficiencies
- List the primary goals of calibrating both a race engine and a production engine
- State why "correction factors" need to be used when reporting "wide open throttle" engine data, and explain how to calculate and use these correction factors
- ECM, Sensors, and Actuators
- Explain why the on-board computer (often called the engine control module or ECM) needs the signals from the various sensors
- Describe the functions of the crank position sensor, cam position sensor, intake air temperature sensor, manifold absolute pressure sensor, mass air flow sensor (if used), exhaust "oxygen" or lambda sensor, throttle position sensor, engine coolant temperature sensor, and knock sensor (if available on your engine)
- Air/Fuel Ratio Control
- Describe how electronic fuel injection systems work, including the factors that affect the mass of fuel injected and the "pulse width" range that must be avoided
- Interpret and explain the "base table" for pulse width (or the equivalence ratio base table for MAF systems)
- Explain how the base pulse width table can be constructed from knowledge of the air trapped in each cylinder each cycle
- Explain how operating conditions that are generally not encountered during experiments in the engine test cell are incorporated in the engine calibration via use of "multipliers"
- Describe why certain multipliers are needed
- Explain why some of the multipliers also require the calibration engineer to specify a "decay rate" and a "clamp"
- Determine how to embed some of these multipliers in the base pulse width table
- Explain the benefits of the MAF-based system in easing the burden on the calibration engineer
- Discuss why "tip-in" and "tip-out" pose special control problems
- Explain proper injection timing and injector targeting
- Identify the benefits of adaptive learning
- Explain why an ECM with individual cylinder trim is advantageous
- Ignition Timing
- Discuss the operating regimes for Minimum advance for Best Torque (MBT) and Knock Limited Spark Advance (KLSA) ignition timing
- Explain the factors that affect the burning rate and, thereby, MBT timing
- Explain why the base ignition timing table is not linear in either engine speed or load
- Describe how "adders" are used to obtain MBT timing for conditions outside of those encountered in the engine test cell
- Explain the benefits of adaptive learning for spark timing control
- The Calibration Process
- Explain why the calibration process must be an iterative procedure to obtain the proper ignition timing and fuel injection pulse width for every "cell" in the two base tables
- Explain that generating the base pulse width table requires few experiments
- Explain how to embed the "load" multiplier for pulse width
- Generate the "start" multiplier, or the "crank" and "warmup" multipliers if your ECM has this option
- Calculate the intake air temperature multiplier
- Discuss how to experimentally generate the battery voltage multiplier using an injector test stand
- Explain why the auto companies take thousands of data points to get MBT timing as accurate as possible in the base table, and why your race team will benefit from an equal effort
- Discuss the issues or dangers (from the engine durability perspective) involved in generating MBT accurately
- Discuss the problem that is encountered when trying to find MBT at low load and two techniques that can be used to overcome this problem
- Explain how to safely identify the Knock Limited Spark Advance regime of engine operation
- Recognize how to determine the values for the ignition timing adders
- Conclusions
- List things you should look for in an after-market ECM
- Concisely review how to generate the base pulse width look-up table, the pulse width multipliers, the ignition timing look-up table, and the ignition timing adders
- Bonus Material: Generating Base Fuel Look-up Tables using WAVE Software
- This demonstration from guest speaker Steve Rawnsley will expose you to:
- Recognize a state-of-the-art engine modeling program
- Understand how to use this program to ease the burden of generating the base pulse width look-up table
- Investigate use of this program to estimate initial values for the base ignition timing look-up table
- Investigate use of this program to estimate some of the pulse width multipliers
- Investigate use of this program to estimate some of the ignition timing adders
- This demonstration from guest speaker Steve Rawnsley will expose you to:
- Bonus Material: WAVE Software Demonstration
- Bonus Material: Engine Control Units Demonstration
- This segment featuring guest speaker Brian Lewis, will demonstrate how to:
- Apply the lessons from the seminar and the engine modeling code to the base tables of an aftermarket ECM
- Examine the pulse width multipliers and ignition timing adders that are available in this control system
- This segment featuring guest speaker Brian Lewis, will demonstrate how to:
About the Instructor: Ronald D. Matthews
Professor Ron Matthews is Head of the General Motors Foundation Engines
Research Laboratory on the campus of the University of Texas at Austin.
He has been actively involved in engines research for 35 years,
including engine control systems since the initial introduction of
on-board computers. Mr. Matthews is currently a member of the SAE
International Board of Directors and an SAE Fellow. He founded the
Formula SAE competition in 1981 and has been the Faculty Advisor for a
Formula SAE team each year since. He has been author or co-author on
over 200 technical papers and reports, mostly in the field of engines.
Is this e-Seminar for You?
This e-Seminar is intended for anyone interested in engine
calibration/programming the on-board computer, especially for race
engines. At a minimum, classification as at least a junior in a
curriculum leading to a BS degree in engineering or experience in
engine development is necessary background for taking this course.
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