Possible sensor problem
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2nd Gear
Joined: Nov 2008
Posts: 6
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Engine temp sensor values
First off great forum, looks like this forum is filled with great information.
I'm getting ready to pick up a bike this weekend, a 2003 ultra classic, and the owner told me that it doesn't seem to have any power until he's rode it about 10-15 miles. He said that it just started happening recently. He had a power commander on it, and his mechanic seemed to think it was the problem so he removed it. The problem went away for a few weeks and now it's back. I'm thinking that it might be the engine temp sensor, or the Intake air temp sensor. Does anyone have any values for these devices, so that I can check them out. I don't believe the check engine light is on. Also what is the procedure for checking the throttle position sensor. I don't have the electrical systems manual for this bike, but I would like to pick one up in the future. Thanks
I'm getting ready to pick up a bike this weekend, a 2003 ultra classic, and the owner told me that it doesn't seem to have any power until he's rode it about 10-15 miles. He said that it just started happening recently. He had a power commander on it, and his mechanic seemed to think it was the problem so he removed it. The problem went away for a few weeks and now it's back. I'm thinking that it might be the engine temp sensor, or the Intake air temp sensor. Does anyone have any values for these devices, so that I can check them out. I don't believe the check engine light is on. Also what is the procedure for checking the throttle position sensor. I don't have the electrical systems manual for this bike, but I would like to pick one up in the future. Thanks
Last edited by Thedroid; Nov 18, 2008 at 06:04 PM. Reason: Unclear title
Thread Starter
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2nd Gear
Joined: Nov 2008
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I'm guessing that the resistance is going to increase as the temperature rises. Maybe the computer interpets an open thermistor as "high" temp and adjusts the fuel accordingly. The bike acts like it needs more fuel at start up, and once it's warmed up its fine. Anybody have any information on this sensor. 2003 ultra classic
Cruiser
Joined: Jun 2005
Posts: 249
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From: Cato, WI
Thedroid -- Found these in my manual for a 2002
Engine Temperature (ET)
Temp 'F Resistance Voltage
32 9750 4.1
68 3747 3.3
86 2417 2.7
122 1080 1.8
158 526 1.0
194 275 0.6
230 153 0.4
Intake Air temp (IAT)
32 9750 4.2
68 3747 3.3
86 2417 2.7
122 1080 1.8
140 746 1.4
Throttle Position sensor returns a voltage from the c pin (GY/V color) with 12vdc applied to center pin (R/W color).
At idle / closed throttle .20 to .60 volts
At WOT 4.6 to 4.9 volts
Hope this helps --- Tom
Engine Temperature (ET)
Temp 'F Resistance Voltage
32 9750 4.1
68 3747 3.3
86 2417 2.7
122 1080 1.8
158 526 1.0
194 275 0.6
230 153 0.4
Intake Air temp (IAT)
32 9750 4.2
68 3747 3.3
86 2417 2.7
122 1080 1.8
140 746 1.4
Throttle Position sensor returns a voltage from the c pin (GY/V color) with 12vdc applied to center pin (R/W color).
At idle / closed throttle .20 to .60 volts
At WOT 4.6 to 4.9 volts
Hope this helps --- Tom
3rd Gear
Joined: Nov 2008
Posts: 7
Likes: 0
first check for an intake vacuum leak. the performance problem will magnify when engine is cold and the fuel demand is higher. just shoot some carb cleaner at the intake flanges at the cylinder head. A change in Idle speed indicates a leak.
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2nd Gear
Joined: Nov 2008
Posts: 6
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cool I'll test these components and also check for an intake leak as soon as I get the bike. I have not had a chance to pick up a manual yet, but will as soon as I can. I'll let you guys know what I find.
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Road Captain
Joined: Sep 2006
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A bad temp sensor won't always throw a bad code. I experienced this with the 99 Road King. Bike got so bad it would not run. After troubleshooting and finding nothing wrong the first part I changed was the temp sensor. I got lucky, the sensor was bad. Oh yea, sensor was 8 years old and had over 100k on it.