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Cruiser
Posts: 111
Prairie Dog Heaven, CO | All,
went up Squaw pass to Echo lake today (~11000 feet) and cruised down to about 7kft in 5th and 6th at low rpm. About half way down I noticed the fueling getting jerky (normally, the vision has some of the best low rpm off-idle fueling I've ever experienced on any EFI bike). And the next time I had to stop (30 miles later) I noticed the idle had gone to 1500 rpm.
After another 10 miles no improvement so I stopped, let the bike cool down a bit while having a coffee, then restarted and all was fine again.
400 miles, no other issues.
Thanks in advance for your suggestions. Tried the search but turned up nothing.
Edited by picard 2010-08-13 11:02 PM
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Visionary
Posts: 1340
Gainesville Fl Home of the Gators | The bike uses a single sensor for both Manifold Absolute Pressure[MAP], and Barometric Pressure[Baro] The sensor is located inside the runner of the rear intake to the head. This means that altitude compensation can only be acomplished when the engine is cycled off, and then on. In the split second before start up; the ECM looks at Baro for any adjustments needed. For the most part it works perfectly fine, but on those mountain climbs it can fool the computer |
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Visionary
Posts: 3006
San Antonio, TX | Kevinx,
Thanks, that is good to know. |
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Cruiser
Posts: 111
Prairie Dog Heaven, CO | kevinx - 2010-08-14 5:16 AM
The bike uses a single sensor for both Manifold Absolute Pressure[MAP], and Barometric Pressure[Baro] The sensor is located inside the runner of the rear intake to the head. This means that altitude compensation can only be acomplished when the engine is cycled off, and then on. In the split second before start up; the ECM looks at Baro for any adjustments needed. For the most part it works perfectly fine, but on those mountain climbs it can fool the computer
Kevin, thanks for your reply. I guess I don't quite understand your explanation. If the ambient pressure increases due to descending in altitude why does the sensor not measure that? There should be a continuous adjustment for fuel as you do up and down in altitude. Every other EFI bike does that. |
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Cruiser
Posts: 62
ESCALON CA. | becuase it is in the intake manifold, when the engine is running it senses "vacuum"
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Cruiser
Posts: 111
Prairie Dog Heaven, CO | yoyo - 2010-08-14 9:34 AM
becuase it is in the intake manifold, when the engine is running it senses "vacuum"
Yes, but that vacuum still changes proportionally to ambient atmospheric pressure. |
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Cruiser
Posts: 111
Prairie Dog Heaven, CO | Sorry if this sounds stupid but isn't the continuous measurement of the amount of air and appropriate adjustment of fuel the whole idea of EFI? In order to calculate the amount of air, the system needs to continuously measure intake pressure and temperature. |
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Visionary
Posts: 3204
Memphis | The EFI on the Vision has an adaptive logic that takes a couple of months to really settle in to your riding style. Big changes in temps or altitudes during that initial break-in seem to cause the hick-ups to be more noticeable. Might also cause seemingly un-associated gremlins to pop up like the radio randomely resetting or certain dash lights to come on. This was more common in the '08's but all of them have a window of goofiness during the first couple of months. Turning the bike off and back on will get its little brain reset after an episode. Might not happen to everybody but if it does it should easily reset. |
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Cruiser
Posts: 111
Prairie Dog Heaven, CO | Thanks for the info SongFan. |
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Visionary
Posts: 1340
Gainesville Fl Home of the Gators | picard - 2010-08-14 11:00 AM
kevinx - 2010-08-14 5:16 AM
The bike uses a single sensor for both Manifold Absolute Pressure[MAP], and Barometric Pressure[Baro] The sensor is located inside the runner of the rear intake to the head. This means that altitude compensation can only be acomplished when the engine is cycled off, and then on. In the split second before start up; the ECM looks at Baro for any adjustments needed. For the most part it works perfectly fine, but on those mountain climbs it can fool the computer
Kevin, thanks for your reply. I guess I don't quite understand your explanation. If the ambient pressure increases due to descending in altitude why does the sensor not measure that? There should be a continuous adjustment for fuel as you do up and down in altitude. Every other EFI bike does that.
Being in the intake tract where vacume signel is drawing on the Borden[sp] tube based sensor means that at best the ECM can make course adjustments. The MAP function is looking at engine load, and not air density. The only way to get anything like a measurement would be to allow the enviroment to applt pressure to the Baro. Do not make the common mistake of thinging that these bikes have a very smart ECM. They are slightly smarter[though much faster] then an early 80's Chevette |
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Visionary
Posts: 1484
LaPorte,Tx. | kevinx - 2010-08-14 9:17 PM
picard - 2010-08-14 11:00 AM
kevinx - 2010-08-14 5:16 AM
The bike uses a single sensor for both Manifold Absolute Pressure[MAP], and Barometric Pressure[Baro] The sensor is located inside the runner of the rear intake to the head. This means that altitude compensation can only be acomplished when the engine is cycled off, and then on. In the split second before start up; the ECM looks at Baro for any adjustments needed. For the most part it works perfectly fine, but on those mountain climbs it can fool the computer
Kevin, thanks for your reply. I guess I don't quite understand your explanation. If the ambient pressure increases due to descending in altitude why does the sensor not measure that? There should be a continuous adjustment for fuel as you do up and down in altitude. Every other EFI bike does that.
Being in the intake tract where vacume signel is drawing on the Borden[sp] tube based sensor means that at best the ECM can make course adjustments. The MAP function is looking at engine load, and not air density. The only way to get anything like a measurement would be to allow the enviroment to applt pressure to the Baro. Do not make the common mistake of thinging that these bikes have a very smart ECM. They are slightly smarter[though much faster] then an early 80's Chevette
Now that's how I like my bike and woman...not too smart, fast and purty!!  |
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first problem - jerky fueling and high idle
