The object of the Piggyback group is to reverse engineer the existing stock engine control unit (ECU) on a 2003 Arctic Cat four stroke 660 cc snowmobile engine. This reverse engineering will allow imporved control of emissions after the addition of a catalyst. Particularly, hydrocarbon (HC) and nitrogen oxides (NOx) emissions will be monitored for optimum performance in the SAE Clean Snowmobile Challenge (CSC). Since HC and NOx emissions are the most important to control in an engine, the CSC has based the emissions part of the competition on measurement of HC and NOx in each of teams’ sleds. One of the goals in this project is to minimize the HC and NOx emissions for a total minimum percentage of emissions required for the greatest amount of design points. (CO emissions are also considered in the test, but are weighted less than the HC and NOx emissions levels). Table 1 lists the operating conditions of engine emissions testing, and scoring for the emissions event is listed in Equation 1. The control on emissions will be attained by modifying the existing engine control unit.
Table 1: Operating Conditions for Emissions Testing
Equation 1: Scoring for CSC Emissions Test
Table 1 and Equation 1 courtesy of SAE CSC 2005 Rules
There are several options in modifying an ECU. A “stand alone” system allows a completely new engine control unit to be employed on the engine. This requires all new sensors, wiring and computer to allow the engine to operate. Another option is to use a “piggyback” or override for the existing ECU. The idea behind the piggyback is to allow a separate control unit or computer programmed microcontroller to bypass the existing engine control unit when certain operating conditions are met by the engine.
3. Sensor Block Diagram
Background information on the operation of ECUs is a major part of our project and a key element in decision between a piggy back system and a stand alone system. The main purpose of the ECU is to determine the pulse width of the fuel injectors. Pulse width is defined as how long the injectors stay on. The pulse width is determined by sensors which act as inputs to the ECU. The ECU looks at the incoming signals, and through programming logic and data tables determines the appropriate pulse width for the situation. Below in Figure 1 a block diagram is shown with the inputs and outputs from the ECU.
Figure 1: Input/Output Diagram for snowmobile Engine Control Unit
Milestones:
 | Proposal for modified milestones and initial deliverables: September 15, 2005 |
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09-16-05 Meet with last year’s team and read all their materials. |
| Review and presentation of 2012 emissions standards. |
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09-20-05 Research data loggers. |
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09-22-05 Order data logger. |
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09-22-05 Take all safety tests and check out tools from Art. Also review 2012 emission standards. |
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9-23-05 Help the Noise and Vibration group get track Dyno up and running. |
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9-29-05 Attach data logger to the sled and get up and running. |
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10-04-05 Post team webpage. |
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10-04-05 Written test plans and control parameters. |
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10-16-05 Execute test plans. |
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10-20-05 Compare test results to that of last year’s team. |
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11-15-05 Construction of first basic stamp controller complete and documentation of piggyback design version 1. |
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11-21-05 Comparison of piggyback controller with and without additional inputs, including throttle positions sensor. |
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12-06-04 Complete and hand in Midterm report. |
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12-12-04 Modify Website for this term |
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SPRING SEMESTER MILESTONES |
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01-15-06 Evaluation of idle air mixture for meeting 2012 emissions standards. |
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03-03-06 Final equipment tested and installed on competition sled. |
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03-13-06 CSC Competition |
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05-03-06 Set up of projects for final review, Maine Day. |
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| Set up and test using eddy current resistance unit, work with dyno jet to get system operational |
| Compare current piggyback controller to stock ECU using current catalyst |
| Construction of first basic stamp controller complete and documentation of piggyback design version 1 |
| Comparison of piggyback controller with and without additional inputs, including throttle posi9tions sensor |
| Presentation of first semester results: December 6, 2005 |
| Evaluation of idle air mixture for meeting 2012 emissions standards |
| Competition pre-testing complete |
| Rebuild engine if needed |
| Final equipment tested and installed on competition sled, March 3, 2006 |
| CSC Competition, March 13th -18th, 2006 |
| Set up of projects for final review, Maine Day: May 3, 2006 |
| Open house, operational review of of project: May 4, 2006 |
| Final Project Report due: May 10 2006 |
Submitted 9-15-05
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Due Date |
Milestones and Comments |
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09-16-05 |
Meet with last year’s team and read all their materials. |
|
09-20-05 |
Research data loggers. |
|
09-22-05 |
Order data logger. |
|
09-22-05 |
Take all safety tests and check out tools from Art. Also review 2010 emission standards. |
|
9-23-05 |
Help the Noise and Vibration group get track Dyno up and running. |
|
9-29-05 |
Attach data logger to the sled and get up and running. |
|
10-04-05 |
Post team webpage. |
|
10-04-05 |
Written test plans and control parameters. |
|
10-16-05 |
Execute test plans. |
|
10-20-05 |
Compare test results to that of last year’s team. |
|
11-15-05 |
Construction of first basic stamp controller complete and documentation of piggyback design version 1. |
|
11-21-05 |
Comparison of piggyback controller with and without additional inputs, including throttle positions sensor. |
|
12-06-04 |
Complete and hand in Midterm report. |
|
12-12-04 |
Modify Website for this term |
|
|
SPRING SEMESTER MILESTONES |
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01-15-06 |
Evaluation of idle air mixture for meeting 2012 emissions standards. |
|
03-03-06 |
Final equipment tested and installed on competition sled. |
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03-13-06 |
CSC Competition |
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05-03-06 |
Set up of projects for final review, Maine Day. |
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05-04-06 |
Open house, operational review of project. |
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05-10-06 |
Final Project Report due. |