ISSUE: Engine stalling, hard starting, erratic idle, excessive backfiring, hesitation or flat spots.
PROBLEM: Throttle body and ECU are not in synchronization. This causes the ECU to deliver incorrect timing and fuel properties to the injectors and the ignition coil. If the throttle body delivers incorrect properties to these components the above listed symptoms will occur. It is also possible that there is a pinch in your wire harness and or loose / dirty battery terminals but the throttle calibration is the most common.
EXPLANATION: Your ECU contains a programmed grid that has been uploaded to it either by the owner, a servicing facility, or the factory. This is commonly referred to as the "map". The map contains crucial pieces of information that it delivers these components as to control the manner in which your vehicle runs. The ECU is told to deliver these values by the systems sensors including: throttle body, crank sensor, coolant temp. sensor, air pressure sensor (barometer), and the air temp sensor. These sensors detect conditions and then inform the ECU on the amount of fuel and the timing that should be used based on that information. Two key examples are throttle position and RPM (revolutions per minute).
It works similar to an excel spreadsheet on an X and Y axis. For practical reasons we will just say that the TPS (throttle position sensor, located on the throttle body) is the only "interactive" or adjustable sensor. If the throttle body sends a signal telling the ECU that at 2200 RPM (idle) the throttle position is 7.8 when in reality the throttle butterfly is actually closed this would effect the starting of the engine as well as the idle. This is the basic concept, just a summary.
To keep your vehicle running at its best and to avoid the issues I recommend that the throttle body be recalibrated every time you change the oil. This can only be done correctly by a servicing facility or you can by the tool to do it your self. The tool is called "Diagnostic and Maintenance kit" and is available for around $300 and quite simple to use after correct instruction. This tool is really something no Cannondale owner should be without. It loads on to a PC, laptop, or PCD and has many valuable features besides the throttle calibration feature.
People always ask the question "how does the throttle and ECU come out of alignment after they are set?". It is argued, but my personal opinion is that the throttle body butterfly, and throttle shaft are connected to the TPS and they loose sync. This is an electrical sensor that sits on the end of the throttle shaft. Mechanical cohabitating with electrical. After hours of abuse, vibration and hard riding, water, mud, heat, etc. they come slightly out of adjustment.
SOLUTION:
1. Plug in your data cable to communicate with your ECU.
2. Open D&M program on your computer.
3. Power on your vehicle.
4. Select to download map.
5. When prompted select to download all as opposed to just throttle calibrations (both options are offered).
6. Select the monitor feature and view the throttle position value.
7. Back out the idle set screw located on the LH side of the throttle body until the throttle value on the monitor stops decreasing (use caution to not completely remove the set screw as it can be very difficult to reinstall).
8. Snap throttle open and let it slam shut at the cam on the throttle body (where the throttle cable connects). This assures that the throttle has closed completely.
9. Close the monitor and select to set throttle position.
10. When prompted select to set minimum.
11. Open the throttle to maximum at the cam and click to set maximum (do not use your twist or thumb throttle to perform this task, it will not open the throttle to the maximum).
12. When prompted click ok to send the new values to the ECU.
13. Open the monitor once again and view the throttle position values.
14. Tighten the idle set screw to increase the throttle position by 3 (ex. if 2.5 now 5.5).
15. Start the engine and let warm to 60 degrees or until the stepper position reaches 205 (this is a sign that the engine is completely warmed up).
16. Set idle to 2200 RPM on the monitor and shut off engine).
If this does not correct the stalling issue check your battery connections. Make sure they are clean and tight. Also make sure that there are star washers between the top of the post and the battery cables. If there are not, I strongly recommend that you go to the local auto parts store and purchase some to install or have installed. They will assure that your battery terminals are not coming loose during a ride.
If the problem persists I recommend that you follow the wire harness through out the vehicle to locate a possible pinched or broken wire. I have seen this on rare occasion but mainly the issues above are more common than an issue with the harness. Issues with the harness are more common with bikes than ATV's.
If you have questions regarding this topic feel free to call one of our techs (310)530-8056. We will be happy to walk you through this process or provide more explanation.
Stalling, Hard Starting, Erratic Idle
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cannondale27
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CdaleRacer0128
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speedracer
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speedracer
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MyCannibal
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