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Discussion Starter · #1 ·
So I have had a c28 code before and replaced the stva about 13,000 miles ago when I got the bike.here recently I’ve ran into a few issues that could be a couple things or just one thing and just wanted to get y’all’s thoughts at first my bike is taking a couple seconds longer then normal to start, doesn’t matter if it’s cold or hot, sometimes it starts before I can think to say start then others it takes a second like in the video, then it started to turn off after start up and I’ll have to start it again and it’ll be fine, but it’ll even randomly turn off at a red light, that’s only happened once. My headlight is starting to go in and out like a voltage problem, but the c28 code is the only code I’m getting and I’ll turn my bike off and turn it back on and it’ll be gone like in the video. Video of problem last time I had issues with the stva It never went away and I don’t have any issues going to redline under load or off load
 

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That's acting like a bad connection. But, it could be a bad STPS too. After you do the warm start, do a full throttle run to the redline. Does C28 come back?
 

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Discussion Starter · #3 ·
That's acting like a bad connection. But, it could be a bad STPS too. After you do the warm start, do a full throttle run to the redline. Does C28 come back?
Nope it runs great, and once it’s off it’ll stay off. Let’s say I’m about to go for a ride now, there’s a chance it’ll start fine and I can go about my business, or it’ll start and stay at cold idle around 2k and then the FI will turn on and it’ll stay on until I turn my bike off and turn it back on and my bike will be completely normal
 

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Dreaming of buttsecks for years...
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It sounds like a sensor issue to me. Could be a dead spot near the fully open position, where it goes to activate fast idle on cold starts. I'll bet it just gets worse over time.
 

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Discussion Starter · #5 ·
It sounds like a sensor issue to me. Could be a dead spot near the fully open position, where it goes to activate fast idle on cold starts. I'll bet it just gets worse over time.
Would it be the stps or the stva? I have extra stps but last time I tried swapping one when I had stva problems I couldn’t clock the stps like I needed to, I ended up buying a whole throttle body with everything on it for 100 bucks
 

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Dreaming of buttsecks for years...
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The sensor. I've learned that the ECM on board diagnostic can't detect some issues with the sensor. All it knows is that the value returned isn't what was expected and thinks the problem is the STVA. Some testing with a multimeter can usually reveal these issues.

Installation of the STPS can be tricky. On the 07, it must be installed with the secondaries in the fully open position. The full procedure is described in the service manual.
 

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Discussion Starter · #8 ·
Turns out it was a bad battery connection making the c28 come up and the ransom shut offs. Flattened the metal connectors so they can fit better on the battery haven’t had any issues since, if anyone ever has similar issues.
 
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