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-C28 options

4K views 19 replies 5 participants last post by  Csmith21 
#1 ·
Hi all, I've been doing some reading thru the forums and seems everything I've read on this code(secondary throttle actuator) the bike experiences loss of power but that's not the case with my bike. How do you know for sure it's a bad STVA and are there other common issues that are linked to that dealer code error? And will it leave NE stranded if I take it out again before a fix?

Edit: title should read 'options.'
 
#2 ·
what it dose is it controls the secondary throttle butterflies ,they are computer controled to open at around 7k rpm and I have heard of people removing the actuator when removing the butterflies and causing this issue when they put it back motopsyco had this problem I think too ,I dont think it will do any thing other then open the butterflies early or late so only a lil mpg issue or small horse power issue -I removed the butterflies and never touched the actuator and never got a code but I think you are safe just the light is an inconvience :thumbup:
 
#3 ·
I'm attempting to make a bypass unit for the c28 code... i found a schematic on how to do it. If it works (I'm a noob at electrical boards) I can make another, pm me if you're interested. It basically tricks the computer into thinking the STVA is still there and functioning properly.
 
#10 ·
sounds like its out of adjustment and cant find how to reset to -0- but I think you have the right idea to just say f it as I luv the way it runs with out the butterflies so much less engine breaking and herky jerky and I bet its even better on your bike cause you dont have the drastic gearing like I do

will done bro :thumbup:way to take matters in to you own hands

and to the OP I hope some of this helps :thumbup:
 
#13 ·
The stc system (valve, actuator, stps, stcu) gets it's input from the ecm depending on which of the 8 maps the ecm is using at any given time.

Low speed/rpm = mostly closed stv
High speed/rpm=mostly open stv
WOT=Wide open stv



the top butterflies are the ones we are talking about they control air flow below 7k rpm if you remove them they will look like the pic below



here is a link from when I did mine http://www.gsxr.com/showthread.php?t=83566&highlight=butterflies
hope this helps
 
#15 ·
yea it sounds like they are not opening up all the way -I would run it with out the airbox and rev it up and hold it at like 8k to 10 k and see if they are all the way open you should be able to see this with out removing the whole air box just open the cover like you were gonna change the air filter -good luck let me know what you find out :thumbup:
 
#16 ·
Didn't you just buy the bike last year? If so, I would assume there is still warranty left in which case I'd drop it off at the dealer and tell them to fix it properly.
 
#19 · (Edited)
I thought I'd update everyone on this issue cause it ended up being something different to all the previous F1 threads I've read.

I took the bike to the dealer because I do have an extended warranty on it. Of course when they opened the bike up (gas tank) to check it the light would not come on. They spent 3 hours looking and plugging unplugging etc... and nothing. For me it never failed that the light would turn on as soon as it hit 6500rpms yet the bugger didn't want to do it at the dealer. I requested he give it a spin on the road to see if he'd get the light.

After giving it a run (and no light) he noticed the bike recycled for a 2nd time when he was taking the key off, which it shouldn't do. That was weirder. SO he opens up the tank area again and takes another look. Pulls a bit further out the connector(with wires) that plugs into the STVA and noticed a tiny nick in a wire. That wire just happens to be the one that would give the C28 signal. That small nick was making contact with the frame and so that was causing the interference. It was making the bike use more gas because it's what triggers that function. Hope that makes sense. Anyways, all it needed was that cable to be heat wrapped so it wasn't exposed and causing the interference. So it was never really a C28 error but it was getting the signal because the faulty wire was making contact. Ok I think I said the same thing at least twice :lol:

The harness doesn't have much wiggle room in that space between the frame and the tank so it's likely to happen to someone else as well. Hope that helps someone out.
 
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