Got a C28 code showing on my K5 electrics, cleaned all connections etc even connected up a spare secondary throttle valve motor i have but code still showing, bike runs ok with this showing but fi light doing my nut in lol
Anything else i can test top track down the fault?
Cheers
Steve
Clean the inside of your ignition key... the electrical bit.
Quote from: Blubber on Saturday, 12 June 2021, 01:38 AM
Clean the inside of your ignition key... the electrical bit.
Done that bud had the whole ignition switch in pieces and cleaned it thoroughly when i was trying to sort my C42 code out
:onya:
C28 is the STV Actuator circuit. Section 4, page 42 in the workshop manual.
Says to check continuity 4.8 - 7.2ohms
The STV has a magnet in it & they have been known to come loose, Snapey has a K5 & his did this. He's a very clever bloke & he managed to repair his, but usually, these are not a repairable unit.
@Snapey
You need to eliminate the magnet issue first Steve by testing that the choke shaft rotates smoothly. Once that tests OK then it's in the electrics. To locate the choke reach under the throttle bodies from the RH side then push the lever up against the slight return spring pressure. (see photo) You'll know if it's not right.
I had the same c28 code reoccurring occasionally and irregularly. You need to ensure the throttle bodies are well balanced and that the TPS and STPS are reading correct Volts for the degree of opening. With mine I found that there was a discrepancy between 1-2 and 3-4 on the secondary side. You can balance the secondaries, or rather correct the offset between the two banks to ensure that the secondary opens the same amount on all 4 cylinders. To do this you need to move the secondary butterfly with your fingers through the airbox while reading the STPS voltage. You can move 1-2 independantly to 3-4, this is how i found there was a difference. You can adjust then by the corresponding screws between the actuator rods for borh banks. I did this until the readings for both sides were the same. This means that the secondaries open the same amount when the actuator tells them to, any difference is registered as a fault and registers as C28.
I also found that by doing this i corrected my fast idle, so now when cold starting, idle is at 2500rpm and slowly drops as the bile warms up, this is how the fast idle was intended to work.
Bit of a long post, hope you get what i mean.
Quote from: Snapey on Saturday, 12 June 2021, 07:31 AM
You need to eliminate the magnet issue first Steve by testing that the choke shaft rotates smoothly. Once that tests OK then it's in the electrics. To locate the choke reach under the throttle bodies from the RH side then push the lever up against the slight return spring pressure. (see photo) You'll know if it's not right.
Had a look at this and the throttle bodies on the bike the return seems quite weak compared to my spare throttle bodies which the return seems quite strong?? Not sure if this is what you mean by you'll know if it's not right?
Here's how it cycles when ignition switched on...... if that helps?
bfbN-UuhCkk
Quote from: SBeachill on Saturday, 12 June 2021, 11:16 PM
Had a look at this and the throttle bodies on the bike the return seems quite weak compared to my spare throttle bodies which the return seems quite strong?? Not sure if this is what you mean by you'll know if it's not right?
All you're doing is pushing against a weak spring so IMO the STVA magnets are OK but I'd be concerned about the spare set if it's quite strong. If there's a loose magnet you should get a scraping/grinding feel. It sounds like your troubles are electrical. Good luck.
Quote from: Snapey on Sunday, 13 June 2021, 01:51 AM
All you're doing is pushing against a weak spring so IMO the STVA magnets are OK but I'd be concerned about the spare set if it's quite strong. If there's a loose magnet you should get a scraping/grinding feel. It sounds like your troubles are electrical. Good luck.
@Snapey Just got hands on a used throttle body that I intend to prepare as a spare, just in case I get in to trouble with the one currently on the bike, and that has more than 120K Km of operation...
Looks like I get grinding feel when hand moving the STVs... so surely a loose magnet, as confirmed by your posts/comments -- this is surely why I got the TB a bargain price, even though the seller "didn't know what was wrong with it, but probably the STPS"...
Would you have some hints/pics about STVA magnets fixing/relocating back in place?
Also, as I guess there is no choice other than fully disassembling the TB and although there is some information on reassembly in the workshop manual, I'm a little concerned about refitting springs and the possibly required 'winding' to get the necessary return forces... Any feedback on that, too?
Cheers
It's a bloody long time since I did a magnet repair but I think the TB's come apart in pairs. It's only when you separate the linkages that the springs are an issue. If you've got basic mechanical skills there shouldn't be a problem. Removing & replacing the TB's from the bike is a much harder job. https://gsx1400owners.org/forum/index.php?topic=338.msg2664#msg2664
Once you've got the TB's apart then stripping the actuator is straight forward. The loose magnet is glued to the shaft 180 deg opposite the one that's in place using a good 24 hour epoxy. The first pic shows the dislodged magnet attached to the outer wall ... hence the scraping feel. Undo the 4 nuts then you can glue the magnet to the shaft.
From memory it's only two damn long bolts that hold the throttle bodies together. Not that I've ever taken mine apart as those bolts feel seized & would snap if I tried.
Quote from: Snapey on Wednesday, 29 December 2021, 10:05 PM
It's a bloody long time since I did a magnet repair but I think the TB's come apart in pairs. It's only when you separate the linkages that the springs are an issue. If you've got basic mechanical skills there shouldn't be a problem. Removing & replacing the TB's from the bike is a much harder job. https://gsx1400owners.org/forum/index.php?topic=338.msg2664#msg2664
Once you've got the TB's apart then stripping the actuator is straight forward. The loose magnet is glued to the shaft 180 deg opposite the one that's in place using a good 24 hour epoxy. The first pic shows the dislodged magnet attached to the outer wall ... hence the scraping feel. Undo the 4 nuts then you can glue the magnet to the shaft.
Many thanks
@Snapey for your swift and most valuable reply. Yes, from the workshop manual it looks like TBs simply come apart in pairs, but I wasn't sure of what happens to the springs then :-)
I'll check that in a few days as soon as I can, and let you know how that went.
Just a quick question about the position of the magnet to be re-glued in place: although I perfectly understand about the 180 deg which seems quite logical, it seems from the second pic that magnets are at, say, 120 deg. Or is that due to the viewing angle?
Do you just have to be unlucky to experience this problem ? :whatever:
Quote from: SpongeBob on Thursday, 30 December 2021, 04:00 AM
Just a quick question about the position of the magnet to be re-glued in place: although I perfectly understand about the 180 deg which seems quite logical, it seems from the second pic that magnets are at, say, 120 deg. Or is that due to the viewing angle?
The second photo shows where the magnet finished after coming loose. Same photo as the first one but only after I removed the stator/laminations. The loose one definitely needs to be positioned opposite the fixed one.
Quote from: GSXKING on Thursday, 30 December 2021, 11:02 AM
Do you just have to be unlucky to experience this problem ? :whatever:
Probably not a common problem but I've done a few so IMO it's the first thing you check if you get a C28 code. If the choke shaft rotates freely but with only slight spring pressure then you can eliminate the magnet & focus on sensors. If you don't check it first & it's faulty then you can spend a week playing with sensors & not get it right.
Thanks
@Snapey I figure I'm very lucky to have had very few issues with my bike then. It does go through a lot of tyres, chains & sprockets however mmmmm 🤣
I hope I haven't just jinxed myself 🤞🤞🤞