Continuing - So what did you do to your bike today...?

[T250]

Had you balanced the throttles first? otherwise it'll be wrong once you do.

Hi Hooli,
To be honest I did not!!
Tickover seemed very smooth and stable pre the TPS adjustment (and still smooth and stable after)..
But I definitely notoced a difference once the TPS was adjusted.. It used to be quite snatchy at low speeds when manoevering say a tight bend..

However, I have splashed out on a set of Morgan Carb / Throttle body balancers which should arrive in the next few days, so I shall do it all again and also "whilst I'm in there" compare the TPS readings at the large grey connector (which I used), with the connector under the tank..
Mat even have a play with the STPS..
If it works it needs adjusting   

S
[/quote]

Morgan carb tune are very good, I still inserted some restrictors I had to stop any bouncing. You will find a difference when measuring at the grey block and the connector under the tank, it has been mentioned on here before as to why, I always take measurements from under the tank for both tps & stps after balancing the tb's

[Eric GSX1400K3]

Enjoy needing three hands to do the SPS. You need to hold the butterflies fully shut to set it, hold the meter probes on the connectors and turn the SPS all at once ...

alligator clips on the multimeter sorts that out

[Hooli]

Yeah I keep saying I'll get some one day

[Will14]

Yeah I keep saying I'll get some one day

Female spade connectors is the way to go, give the spades a squeeze with a set of pliers and they go straight on to the pins in the plug & the multi meter probes go in the back end of the spade connectors perfectly. I found that the croc clips were a bit to wide to fit on the pins     

[Tony Nitrous]

Removing old thin foam layer and glue from the Gen-2's wheels where previous wheel weights had been. Wasn't difficult with some brake cleaner but the last owner and guy he got to sell the bike didn't think it was worth doing despite looking so ugly.

Fitted the 4 new (not cheap) screws to the B-Kings belly pan, convinced myself that although getting stung on price they'd been on and off for over 15 years with very little love.

Looked at the B-Kings new airfilter and push pin clips sat on the bench that need fitting to the B-King but wasn't in the mood to start pulling the side pods, indicators, tank cover, chrome trim, smart key reader, etc etc etc off today.

[Hooli]

I've been thinking about my C28 error and how it fails.

Initially the STVA is correct, doing the normal movement when the ignition is turned on.I get fast idle when the bike starts but then the fast idle climbs as the STVA goes to full rotation and then the code appears.
Now it says elsewhere in the manual that the ECU only knows the position of the STVA by comparing the TPS and SPS readings, which makes sense as there's only two wires to the STVA.
I think I've got a failed SPS so the ECU isn't seeing any movement from the STVA. Therefore the ECU flags a STVA error.
I'll test the SPS later but might end up getting a replacement anyway. After all it's original and I'm on my third TPS, none of which tested faulty when they failed.

let us know how you get on, with mine the error comes up at random on a ride, seems after a sudden throttle opening, like when overtaking. I get proper fast idle and it then settles down to 1100 rpm once warm.

If I'm gentle with the throttle it won't pop up, but if I'm turning the wick up, it seems to occur.

Yeah it wasn't that, proved it with some fiddling on friday. I did have one of the plastic T-pieces in the vacuum hoses snap when I touched it so I replaced all them, didn't help though.
So I ignored it for the weekend & rode my tractor. It's getting annoying now as I still can't find what's wrong with the damn 14, the manual just says replace the throttle bodies & ECU but that seems a touch drastic & expensive.

I still haven't fixed this BUT following some more research online I came across this thread on a GSXR forum https://www.gixxer.com/threads/c28-c29-with-a-confirmed-working-stva.557586/ Now their setup is slightly different to ours, on a GSXR the STVA & SPS are in the same unit fitted to the end of the throttle bodies, hence all the fix videos you see show a four pin connector being soldered up. But they work in exactly the same way, all the bits on the bike look the same ECU etc wise so it's the same kit mapped differently with a few packaging changes.

Now in that linked thread someone called TheGeek says

There are multiple circuits in the system. A loose connection on any of them can cause the ECU to think there's a problem. The logic of it all is really simple, but easy to confuse.

C28 can be caused by open circuits of the STVA, or unexpected data from the sensor.
C29 can be caused by open circuits or data out of range.

Two identical circuits on the STVA not shared with any other system on the bike. Direct lines to the ECU. I've seen loose sockets on both ends of the wiring harness cause C28 issues. These can usually be found by manipulating the wires at the coupler to cause or eliminate problems.

The STPS is where most people get confused. On the 06/07, there are three wires on the sensor. Black, yellow, and blue. Blue is the power input, black is ground, and yellow is the pickup. The manual has tests for the STPS, but in my opinion was written by a moron. Some of the conditions they want you to test for can't exist.

In essence, the sensor is just a variable resistor. Resistance across the Black and Blue wires should be static. I've seen readings anywhere from 4.3k Ohms to 5.5k Ohms. As the wiper rotates, it picks up a voltage. The further the wiper is from the power input, the lower the pickup voltage. This is why you test across the Yellow and Blue wires for calibration. What I've seen in some cases is that the sensor gets contaminated and has a short across the wiper pads. When this happens, you basically get a parallel resistor circuit with one resistor being variable. You can diagnose this by seeing a change in the static circuit with movement.

Most of the time, you'll see the secondaries try to open and then move back to closed at half speed and chatter. This is because the ECU is getting data from the STPS that doesn't match what it's telling the STVA to do. Since it sees the sensor, and data from the sensor in the expected range, it assumes the STVA is the problem and throws a C28.

So what I did was follow his logic & test my SPS for variable resistance between Blue & Black, which isn't a test in the workshop manual as far as I recall. I get exactly the same variable resistance on Blue & Black as I do on Blue & Yellow. So I've got the fault he describes. Which means my original logic quoted was correct, I just hadn't found why it was happening because I'd trusted the manual and not thought of this fault.

Prior to this I'd poked two wires in the back of the ECU connector & run them down to the connection at the bottom of the STVA, therefore eliminating the entire loom & proving the issue wasn't a wiring fault.

So it looks like I do need a SPS after all. I might try & convince someone I know to let me borrow theirs so I can prove it before I order one, but at least I can finally see a problem to explain what's going on. A dirty/worn SPS also explains why it's been an intermittent fault for ages too, same as I've had when TPS fail. They are exactly the same thing after all.

Update!

I finally borrowed a SPS of a friend's bike yesterday, it fixed my issue. I'll need to readjust the fast idle cam, no surprise as the faulty SPS will have meant the STVA was in the wrong position. But the bike runs fine & no error codes.

I've now ordered a SPS from www.bike-parts-suz.com for just under £128 delivered, which is the cheapest I could find.

[Eric GSX1400K3]

Awesome mate, I will check my stps for variable resistance across the wires.  Shame they can't be serviced or cleaned.  Great write up.

[grog]

I bought mini GSXR indicators while back. One came loose. Advice, if you get similar. 10mm threaded rod goes into light housing, take it out, loctite it, then loctite nut also when fitting.Hope this helps someone.

[Tony Nitrous]

Today.

Found somewhere to test 6th gear.

I can confirm 6th gear works at higher revs too.

It's not a slow bike.

[Eric GSX1400K3]

Wiped the dust from the rh side of the speedo plate did we?

[Hooli]

It's important to check such things occasionally.

[grog]

Looks fast just sitting there.

[Tony Nitrous]

Wiped the dust from the rh side of the speedo plate did we?
[/quote

Looks fast just sitting there.

It'll be interesting to get it to the drags or dyno, but I'm thinking it's a bit stronger than my old H2 or Gen-1's or my B-King or Gen-3. It feels quite healthy.

[Hooli]

I've been thinking about my C28 error and how it fails.

Initially the STVA is correct, doing the normal movement when the ignition is turned on.I get fast idle when the bike starts but then the fast idle climbs as the STVA goes to full rotation and then the code appears.
Now it says elsewhere in the manual that the ECU only knows the position of the STVA by comparing the TPS and SPS readings, which makes sense as there's only two wires to the STVA.
I think I've got a failed SPS so the ECU isn't seeing any movement from the STVA. Therefore the ECU flags a STVA error.
I'll test the SPS later but might end up getting a replacement anyway. After all it's original and I'm on my third TPS, none of which tested faulty when they failed.

let us know how you get on, with mine the error comes up at random on a ride, seems after a sudden throttle opening, like when overtaking. I get proper fast idle and it then settles down to 1100 rpm once warm.

If I'm gentle with the throttle it won't pop up, but if I'm turning the wick up, it seems to occur.

Yeah it wasn't that, proved it with some fiddling on friday. I did have one of the plastic T-pieces in the vacuum hoses snap when I touched it so I replaced all them, didn't help though.
So I ignored it for the weekend & rode my tractor. It's getting annoying now as I still can't find what's wrong with the damn 14, the manual just says replace the throttle bodies & ECU but that seems a touch drastic & expensive.

I still haven't fixed this BUT following some more research online I came across this thread on a GSXR forum https://www.gixxer.com/threads/c28-c29-with-a-confirmed-working-stva.557586/ Now their setup is slightly different to ours, on a GSXR the STVA & SPS are in the same unit fitted to the end of the throttle bodies, hence all the fix videos you see show a four pin connector being soldered up. But they work in exactly the same way, all the bits on the bike look the same ECU etc wise so it's the same kit mapped differently with a few packaging changes.

Now in that linked thread someone called TheGeek says

There are multiple circuits in the system. A loose connection on any of them can cause the ECU to think there's a problem. The logic of it all is really simple, but easy to confuse.

C28 can be caused by open circuits of the STVA, or unexpected data from the sensor.
C29 can be caused by open circuits or data out of range.

Two identical circuits on the STVA not shared with any other system on the bike. Direct lines to the ECU. I've seen loose sockets on both ends of the wiring harness cause C28 issues. These can usually be found by manipulating the wires at the coupler to cause or eliminate problems.

The STPS is where most people get confused. On the 06/07, there are three wires on the sensor. Black, yellow, and blue. Blue is the power input, black is ground, and yellow is the pickup. The manual has tests for the STPS, but in my opinion was written by a moron. Some of the conditions they want you to test for can't exist.

In essence, the sensor is just a variable resistor. Resistance across the Black and Blue wires should be static. I've seen readings anywhere from 4.3k Ohms to 5.5k Ohms. As the wiper rotates, it picks up a voltage. The further the wiper is from the power input, the lower the pickup voltage. This is why you test across the Yellow and Blue wires for calibration. What I've seen in some cases is that the sensor gets contaminated and has a short across the wiper pads. When this happens, you basically get a parallel resistor circuit with one resistor being variable. You can diagnose this by seeing a change in the static circuit with movement.

Most of the time, you'll see the secondaries try to open and then move back to closed at half speed and chatter. This is because the ECU is getting data from the STPS that doesn't match what it's telling the STVA to do. Since it sees the sensor, and data from the sensor in the expected range, it assumes the STVA is the problem and throws a C28.

So what I did was follow his logic & test my SPS for variable resistance between Blue & Black, which isn't a test in the workshop manual as far as I recall. I get exactly the same variable resistance on Blue & Black as I do on Blue & Yellow. So I've got the fault he describes. Which means my original logic quoted was correct, I just hadn't found why it was happening because I'd trusted the manual and not thought of this fault.

Prior to this I'd poked two wires in the back of the ECU connector & run them down to the connection at the bottom of the STVA, therefore eliminating the entire loom & proving the issue wasn't a wiring fault.

So it looks like I do need a SPS after all. I might try & convince someone I know to let me borrow theirs so I can prove it before I order one, but at least I can finally see a problem to explain what's going on. A dirty/worn SPS also explains why it's been an intermittent fault for ages too, same as I've had when TPS fail. They are exactly the same thing after all.

Update!

I finally borrowed a SPS of a friend's bike yesterday, it fixed my issue. I'll need to readjust the fast idle cam, no surprise as the faulty SPS will have meant the STVA was in the wrong position. But the bike runs fine & no error codes.

I've now ordered a SPS from www.bike-parts-suz.com for just under £128 delivered, which is the cheapest I could find.

It's here...

[Hooli]

Update on that ^^ (to save quoting it all again).

New sensor fitted in my lunch break as I'm working from home. My 14 now runs without error codes, I'll try it again in 4hrs or so when I've finished for the day to see what the fast idle is like, I had to tweak it a bit but not sure it was enough. Somewhere on here someone once quoted how to set the fast idle up, I can recall a voltage of 1.195v but not where or when to measure it.

But it's looking good for fixing the C28 error. I'll be off to a bike night tonight so I'll check if it works when ridden then, but I'm confident about it.