08 Spyder GS SM5 misfire/stumble when riding at steady speed

My Spyder is driving me crazy. I've been trying to figure out why the engine is misfiring or stumbling whenever I am cruising along at a constant speed. If I open the throttle it immediately cleans up and pulls hard. It feels like its running out of gas like the old days when it was time to switch the petcock to reserve. I've run a couple of bottles of Techron fuel injector cleaner through it. It has almost 12k miles on it so I went ahead and replaced the plugs and wires (Baja Ron, with Iridium plugs), air and fuel filter, MAP sensor vacuum tubes, did the canisterectomy, and tightened the ground bolt under the seat. I thought that I had finally found the problem when I took off the body work and started looking closely at every hose and fitting. I found cracks in both intake flanges so I replaced them. No help it still stumbles while cruising steady speed. As much as I don't want to I'm starting to think about taking it to the dealer and have them look at it. Before I do that, does anyone have any further suggestions?

'08 Spyder GS SM5
'09 Suzuki DL650
Yorktown, VA

Not sure what problem is, but I heard that the dealership in Gloucester has a certified Spyder mechanic that used to work for a dealership. Without BUDS to monitor other sensors like the cam position & MAP sensors, probably will be difficult. If you apply gas and it clears up I would assume it is a sensor connected to vacuum (MAPS??). I would doubt a carb problem and the coil pack doesn't fit the problems.

On mine it pops (backfires?) when it gets hot (5-6 bars). Did all the same stuff you did. I do have the unit that you plug in when you add custom exhaust, might put that on and see if tweaking mixture helps.

I'm still determined to get the BUDS software someday, but $800 is pricey and wife won't let me :)

I have been wondering if it might be a problem with either the MAP sensor or the fuel pressure regulator. I don't want to spend the money on just replacing them to see if it helps. But if it did it would be cheaper than a trip to the dealer.

Did you ever figure out the problem, I’m having the same issue and can’t find out why?

No I haven't solved the problem yet. I'm going to have to let the dealer look at it and see if they can find the problem.

FWIW. I also have an '08 GS SM5. When I bought it in 2012 it had the same symptoms, though the stumbling at constant throttle was maybe not as bad as yours.
I purchased a used electronic gizmo from someone on this board. I removed the oxygen sensor & screwed in the supplied blank plug. Followed the oxygen sensor wiring to under the battery area & unplugged it. Plugged in the small gizmo I had bought. All done.
I believe the gizmo somehow slightly richens the mixture so doing away with the stumbling.

Unfortunately the items are no longer made & I haven't seen one for sale on here in a very long time. Cost me $50.

Things to check out would be.... plug wires known to be a bit feeble on the older models, the spark plug and go with the iridium plugs, the vaccum tubes to the throttle body and replace with the silicone ones and the intake manifold that can dry out and start cracking. Finally test the coils. Fuel side you can check the or replace the fuel filter otherwise the fuel seems to not be issue as you have cleaned the injectors and fuel is flowing...:thumbup:

Did the original poster ever find out what the cause is? I am having the exact same symptoms on my 08 GS SM5. I also did everything the OP did to fix it without success. The only thing I can think of is the GPS. Mine has been acting up for some time and have a new one order. When it gets replaced, i will ask the tech to do a full diagnostic with BUDS. Hopefully that will resolve it once and for all.

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Originally Posted by jayallday01

Did the original poster ever find out what the cause is? I am having the exact same symptoms on my 08 GS SM5. I also did everything the OP did to fix it without success. The only thing I can think of is the GPS. Mine has been acting up for some time and have a new one order. When it gets replaced, i will ask the tech to do a full diagnostic with BUDS. Hopefully that will resolve it once and for all.

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Did you change out the 2 vacuum hoses on the throttle body?

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Originally Posted by BajaRon

Did you change out the 2 vacuum hoses on the throttle body?

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Yes sir. And yet the issue persists. I may try the MAP sensor next. The GPS definitely needs to be replaced as it wont show the correct gear although I know exactly what gear I am in.

I am the OP and no I still haven't gotten the problem fixed. I'm out of ideas and will have to resort to taking the GS in to the dealer even though I don't have much confidence in them. I'm planning on making an appointment with a dealer that does laser alignments and while they have it ask them to check it out. I'm wondering if there is a flash update that needs to be loaded in connections to this problem. I'm not sure when I will do this, so when you have the dealer look at yours please update us with the results of that visit.

Thanks,

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Originally Posted by bwbarnes

I am the OP and no I still haven't gotten the problem fixed. I'm out of ideas and will have to resort to taking the GS in to the dealer even though I don't have much confidence in them. I'm planning on making an appointment with a dealer that does laser alignments and while they have it ask them to check it out. I'm wondering if there is a flash update that needs to be loaded in connections to this problem. I'm not sure when I will do this, so when you have the dealer look at yours please update us with the results of that visit.

Thanks,

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Yes sir, I will definitely let you know. Have you had any issues with the Gear Position Sensor on your GS? I am hoping this is the culprit and remove and replace fixes it. Thanks for replying...I know its an older post.

No, I haven't had any problems with the gear position sensor. The Spyder has been great other that the annoying misfire around 55mph. I was hoping that a long trip would help and took a weekend ride to the mountains last fall. The Spyder got a good run up and down the mountains but it didn't help the problem. The misfire seems to come and go in severity. Its never really bad, just bad enough to be annoying.

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Originally Posted by jayallday01

Yes sir, I will definitely let you know. Have you had any issues with the Gear Position Sensor on your GS? I am hoping this is the culprit and remove and replace fixes it. Thanks for replying...I know its an older post.

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My guess is the O2 sensor is bad. Some O2 sensors can pick up resonance in the exhaust and send a faulty signal to the ECM. My victory motorcycle does this when cruising at a steady speed and clears up when I crack the throttle. I have an AFR gauge on the bike and can see it go full lean when it happens. I have the new O2 sensor ready to install. My guess is your spyder has a similar problem. It especially occurs with aftermarket exhaust.

Post one description sounds lean. If not oxygen sensor, then:

1. Check for minor vacuum leak

2. What is condition of air filter?

3. When spark plugs were changed, what did gap measure? (a) on old plugs?...(b) on new plugs?
Iridium are supposed to be pre-gapped, but impact on the ground prong could narrow gap.

Let’s go back to O2 sensor:

4. How many wires to O2 sensor? My Ryker is 4 wire, with two wires for heater.

5. Per the manual, what are resistance and/or output values?

6. Has sensor connector been disconnected and then reconnected to wipe the contacts?

7. Any corrosion present at connector?

Has the PCV valve been checked? A sticking PCV valve can give you a lean mix and create this kind of problem as well.

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Originally Posted by BajaRon

Has the PCV valve been checked? A sticking PCV valve can give you a lean mix and create this kind of problem as well.

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Hi, can you point me in the right direction as to where the pPCV Valve is located? Thanks.

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Originally Posted by jayallday01

Hi, can you point me in the right direction as to where the pPCV Valve is located? Thanks.

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Follow the hose from your evap canister to the engine (canister is located on the right side of the engine, off to the side). At the engine side the hose connects to the PCV valve. An easy way to check if this is your problem is to disconnect the hose from the evap canister and plug it there. Then go for a ride. If it is a leaking PCV valve (and you have plugged the hose so there are no leaks) your problem will clear up.

It's a bit of a long shot. But easily checked and a possible solution. At least you can eliminate this one easily before you spend time and money on more expensive solutions.

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Originally Posted by BajaRon

Follow the hose from your evap canister to the engine (canister is located on the right side of the engine, off to the side). At the engine side the hose connects to the PCV valve. An easy way to check if this is your problem is to disconnect the hose from the evap canister and plug it there. Then go for a ride. If it is a leaking PCV valve (and you have plugged the hose so there are no leaks) your problem will clear up.

It's a bit of a long shot. But easily checked and a possible solution. At least you can eliminate this one easily before you spend time and money on more expensive solutions.

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Thanks sir. I should have realized thats where it is considering I removed the evap canister a while back. I did observe the bolt I used to plug the hose was backed out a bit. Snugged that up and started the bike. No rough idle as it had been. Test ride to occur later today. Thank you for the advice. Always appreciated.

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Originally Posted by jayallday01

Thanks sir. I should have realized thats where it is considering I removed the evap canister a while back. I did observe the bolt I used to plug the hose was backed out a bit. Snugged that up and started the bike. No rough idle as it had been. Test ride to occur later today. Thank you for the advice. Always appreciated.

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I always use some silicone sealant on the bolt in the hose plug just to be sure. Some have even put a hose clamp on it. It would be great if this fixes your issue.

A minor vacuum leak will cause rough idle / rough low RPM operation.
When throttle is opened, the % increase in air is neglible.

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Originally Posted by SportsterDoc

A minor vacuum leak will cause rough idle / rough low RPM operation.
When throttle is opened, the % increase in air is neglible.

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In general. I would completely agree with you. However, the Spyder already runs pretty lean (after warm-up). Some Spyders seem to have a problem with the rear cylinder running leaner than the front. In a situation where you're already borderline. And considering that at cruise you get your highest vacuum (other than decel). It could be that a normally insignificant vacuum leak could be the straw that breaks the camel's back.

This is why I thought it worth a look. Can't hurt.

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Originally Posted by BajaRon

In general. I would completely agree with you. However, the Spyder already runs pretty lean (after warm-up). Some Spyders seem to have a problem with the rear cylinder running leaner than the front. In a situation where you're already borderline. And considering that at cruise you get your highest vacuum (other than decel). It could be that a normally insignificant vacuum leak could be the straw that breaks the camel's back.

This is why I thought it worth a look. Can't hurt.

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Agreed.
A vacuum leak was suggestion 1 in post 15.

I am just going to toss this out and see if it sticks.....
I had a customer who had the same problem, the dealer in
Lodi CA. ( now defunct )could not find the problem so just on
a whim the owner went to NAPA auto and bought some fuel injector
cleaner and put it in the gas tank.... guess what it worked .

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Originally Posted by bwbarnes

The Spyder has been great other that the annoying misfire around 55mph. I was hoping that a long trip would help and took a weekend ride to the mountains last fall. The Spyder got a good run up and down the mountains but it didn't help the problem. The misfire seems to come and go in severity. Its never really bad, just bad enough to be annoying.

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Just wondering if you did a catalitic converter removal (cat-delete) Some owners do that and that could change the mixture being put into the intake by the computer and injectors since they dont get the same signals originally programed for. Just somethig to consider. not an expert here but a friedn did that and her F3 goes from limp mode to limp mode now. Don't know what else she messed up with. I heard she sold it last week!