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Discussion Starter #1
I'm experiencing an issue with the bike having a surging sensation at steady throttle. A search on the forum shows that others experience this as well. I took my bike to my local dealer and they we able to reproduce the issue on a test ride and are investigating a solution. Has anyone actually found the cause of the problem? I'd like to point the dealer in the right direction and get this fixed while still under warranty!
 

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My guess is too lean fueling, the 1000 still isn’t perfectly dialed in. Guess chance the throttle bodies could need synced, but would be odd for a bike under warranty.
 

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Discussion Starter #3
My guess is too lean fueling, the 1000 still isn’t perfectly dialed in. Guess chance the throttle bodies could need synced, but would be odd for a bike under warranty.
Thanks for the suggestions.
They synced the throttle bodies (slight alignment made) and the throttle position sensor was verified. Issue persists.

To me it almost feels like a rev limiter kicking in very briefly...but it happens way below the red line (ie 4000 rpms).
 

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Is your problem during the very light throttle positions and below 3000 rpm? If so, maybe this thread is relevant.
 

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Discussion Starter #5
Is your problem during the very light throttle positions and below 3000 rpm? If so, maybe this thread is relevant.
I notice it significantly more around 4000 rpm, but it also occurs at lower rps as well.

I read through that thread, but my issue isn't with on/off throttle response, but at constant throttle.

For example, 4000 rpm in 4th gear - around 90 km/h. It isn't constant, but I get a several small lurches (or surge or whatever). Nothing significant enough to register in the tachometer. I can gear up or down and it usually goes away for a while.
 

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Small comfort but is not just Suzuki. Other brands are experiencing the same surge. It is that area on the cusp of open-loop and closed-loop for the fueling. Euro 4 (EU 4) became the standard in 2016. The short answer is that is too lean.
Motorcyclist tester guys tried to sort it our with a Power Commander but all the stock maps failed. They contacted Dale Walker. "... Dale Walker, who has spent an ungodly amount of time working on the V-Strom 1000 and developing his own tuning module. He found that the stock bike was tuned quite lean most of the time—between 14.5 and 14.7:1..."
I doubt that Suzuki would agree to give you a ECU from a 2015 / 2016. I also doubt that they have much they can do for you. It might leave you with a bad taste but if it were me, I'd just buy a BoosterPlug. Send Jens at Booster an email. I'm pretty sure he will let you return it if you aren't satisfied.
 

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Small comfort but is not just Suzuki. Other brands are experiencing the same surge. It is that area on the cusp of open-loop and closed-loop for the fueling
I am far from an expert on this but isn’t cruising at steady throttle at 4000rpm already running in closed loop. And my understanding is that with the booster plug the bike will go back to its original settings in closed loop anyway. Am I wrong?
 

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I am far from an expert on this but isn’t cruising at steady throttle at 4000rpm already running in closed loop. And my understanding is that with the booster plug the bike will go back to its original settings in closed loop anyway. Am I wrong?
You might be right, ... but I don't know. I don't know what "calls" the loop change over or when. But it likely references the air temperature, in part.
If @mfaulkner emails over to Jens he will get a quick response and the right answer.
I'm hoping mfaulker will update us, one way or the other.
 

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You might be right, ... but I don't know. I don't know what "calls" the loop change over or when.
From what I understand it is mainly throttle position or more precisely, rate of change in throttle position. The O2 sensors in modern bikes are what is called "narrow band" which means they can detect accurate oxygen levels right around stoichiometric A/F ratio of 14.7 which is the goal of the regulators to minimize emissions. The O2 sensors are too slow and not accurate enough outside of a narrow band or range right around 14.7 A/F ratio for the ECU to control fueling strictly through the O2 sensor feedback which is why they still use a fuel map too. Even in "closed loop" mode the ECU is still using a map but slightly modifying its injector/fuel demand with feedback from the O2 sensor. Theoretically, the ECU detects when the throttle position is holding steady or gradually moving and kicks into closed loop mode to read the O2 sensor and adjusts the fueling to minimize emissions. In theory.

But it likely references the air temperature, in part.
The ECU is looking at all parameters to pick and/or modify a fuel map and also the rate of change in the throttle position to decide to go into closed loop mode. So the OP's problem is that the ECU is probably hunting between maps despite being in closed loop mode. My hypothesis on how that can happen is related to a tolerance stack, as with assembled mechanical parts.

When engineers design mass produced parts destined for assembly they specifiy the nominal dimension and a tolerance +/- some small value. A tolerance stack analysis means that someone does the math to verify that if a bunch of parts slated for assembly randomly gets all nominal parts minus the tolerance (or alternatively, plus the tolerance) it will still work and allow assembly.

So the same concept applies to the sensors feeding the ECU. All the sensors have a nominal value +/- a range of allowable values. So the problem is that some random collection of sensors reading high or low (but still within tolerance) can put the ECU right on the edge of flipping between fuel maps. There are 6 engine related input sensors to the ECU -- TPS, STPS, IAP1, IAP2, IAT and ECT. So looking at a tolerance stack and assuming 2 possible states (Nominal +/- some tolerance) means that in any randomly built bike there are nearly 480K possible permutations of a tolerance stack (2*6=12 thus 12 factorial).

It is highly unlikely that Suzuki has done the Monte Carlo analysis to insure that, on average, very few bikes (~1%) will get a sensor tolerance stack that will put the ECU right on the edge between two fuel maps. The problem isn't just that the manufacturers are trying to run the motors as lean as possible to appease the regulators but that the fuel maps are discretely defined. The only fix is a faster ECU and the capacity to store more granular fueling maps so that if a sensor stack puts a bike right on the edge between two maps the switching between maps is not noticeable. Lest we forget, the V-Strom is a budget bike and a faster ECU with more memory is more expensive so it maybe a while before Suzuki gets around to this.

If [he] emails over to Jens he will get a quick response and the right answer. I'm hoping @mfaulker will update us, one way or the other.
I'm guessing, based on the above and what I know about the Boosterplug, that it will probably fix his issue but not from solving a lean condition but pushing the ECU into the middle of a map where it won't hunt. The long term fix that doesn't require the customers to hack their bikes is that Suzuki upgrades the ECU to address this problem. This is especially important for motorcycles because unlike cars there isn't 6 or 8 cylinders and lots of rotating mass to compensate for (or mask) fueling errors coming from the ECU.
 

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Discussion Starter #10
I'm taking the bike back to dealership on Thursday.

Last week they "recorded" something during their test ride when they reproduced the issue. They were supposed to send it to an expert within Suzuki for analysis, but they called me today to tell me that the file was corrupted so they want to do it again. Not sure what they were recording but I got the impression that the on board computer on the Vstrom was doing it.

I'll probably wait to see what they can do for me before I look for an after market solution.

Sent from my SM-G960W using Tapatalk
 

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From what I understand it is mainly throttle position or more precisely, rate of change in throttle position. The O2 sensors in modern bikes are what is called "narrow band" which means they can detect accurate oxygen levels right around stoichiometric A/F ratio of 14.7 which is the goal of the regulators to minimize emissions. The O2 sensors are too slow and not accurate enough outside of a narrow band or range right around 14.7 A/F ratio for the ECU to control fueling strictly through the O2 sensor feedback which is why they still use a fuel map too. Even in "closed loop" mode the ECU is still using a map but slightly modifying its injector/fuel demand with feedback from the O2 sensor. Theoretically, the ECU detects when the throttle position is holding steady or gradually moving and kicks into closed loop mode to read the O2 sensor and adjusts the fueling to minimize emissions. In theory.



The ECU is looking at all parameters to pick and/or modify a fuel map and also the rate of change in the throttle position to decide to go into closed loop mode. So the OP's problem is that the ECU is probably hunting between maps despite being in closed loop mode. My hypothesis on how that can happen is related to a tolerance stack, as with assembled mechanical parts.

When engineers design mass produced parts destined for assembly they specifiy the nominal dimension and a tolerance +/- some small value. A tolerance stack analysis means that someone does the math to verify that if a bunch of parts slated for assembly randomly gets all nominal parts minus the tolerance (or alternatively, plus the tolerance) it will still work and allow assembly.

So the same concept applies to the sensors feeding the ECU. All the sensors have a nominal value +/- a range of allowable values. So the problem is that some random collection of sensors reading high or low (but still within tolerance) can put the ECU right on the edge of flipping between fuel maps. There are 6 engine related input sensors to the ECU -- TPS, STPS, IAP1, IAP2, IAT and ECT. So looking at a tolerance stack and assuming 2 possible states (Nominal +/- some tolerance) means that in any randomly built bike there are nearly 480K possible permutations of a tolerance stack (2*6=12 thus 12 factorial).

It is highly unlikely that Suzuki has done the Monte Carlo analysis to insure that, on average, very few bikes (~1%) will get a sensor tolerance stack that will put the ECU right on the edge between two fuel maps. The problem isn't just that the manufacturers are trying to run the motors as lean as possible to appease the regulators but that the fuel maps are discretely defined. The only fix is a faster ECU and the capacity to store more granular fueling maps so that if a sensor stack puts a bike right on the edge between two maps the switching between maps is not noticeable. Lest we forget, the V-Strom is a budget bike and a faster ECU with more memory is more expensive so it maybe a while before Suzuki gets around to this.



I'm guessing, based on the above and what I know about the Boosterplug, that it will probably fix his issue but not from solving a lean condition but pushing the ECU into the middle of a map where it won't hunt. The long term fix that doesn't require the customers to hack their bikes is that Suzuki upgrades the ECU to address this problem. This is especially important for motorcycles because unlike cars there isn't 6 or 8 cylinders and lots of rotating mass to compensate for (or mask) fueling errors coming from the ECU.
Thanks dmfdmf. Easily the best explanation I've read, to date. A very famous guy once said that if you can't explain something simply, then you don't know it well enough.
The crowd over on a Aprilia site are buying accelerated O2 sensors but I'm not sure how many know why.
Thanks again.
 

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Last week they "recorded" something during their test ride when they reproduced the issue. They were supposed to send it to an expert within Suzuki for analysis, but they called me today to tell me that the file was corrupted so they want to do it again. Not sure what they were recording but I got the impression that the on board computer on the Vstrom was doing it.
I don't want to be too cynical but I'd bet there was no "corrupted" file but the expert saw a known problem that they can't or don't want to fix and after the retest will come back and say "everything is normal, there is nothing wrong with your bike". Since the surges aren't enough to register on the tachometer it probably isn't a vacuum leak (which can cause surging, hopefully Suzuki has already ruled that out) but pointing to lean-surge or map-hunting.

I'll probably wait to see what they can do for me before I look for an after market solution.
That is the best strategy but you have to jump through their hoops and see how it plays out.

One thing you can try (once Suzuki is out of the picture) is to unplug the Intake Air Temp sensor. This is a "fail-safe" sensor and the bike will start and run but you will get a Fault Indicator (FI) light. Without input from the IAT the ECU assumes that it is 25C/104F so if the actual temp is much lower than that the bike will be running very lean. It won't hurt to take the bike on a road test but you don't want to run like that for a long distance. If the problem is lean surging this should make it worse and solution would probably be to get a Boosterplug.

If unplugging the IAT sensor makes the problem go away then you probably have sensors that are causing the ECU to map-hunt. The most important inputs to the ECU for selecting/modifying a map are throttle position, air intake pressure (F/R) and intake air temp. As I suggested above, the bike has a random draw of sensors that, despite all being perfectly normal and operating within acceptable ranges, just aren't playing well together. These sensors are very expensive so it is unlikely that Suzuki will replace them on a guess from something you read on the internet. However, you might be able to convince them to swap the IAP #1 and #2 (and redo the TB sync) and swap the primary and secondary TPS to see if that fixes the problem or you could do this test yourself once Suzuki gives up. The sensor swaps (and maybe a new IAT sensor which is the cheapest sensor at $40) might change the inputs to the ECU enough stop the map-hunting.

NB: I have no idea if this will work and you might be chasing your tail but it would be my strategy if it were my bike so no "warranty" express or implied. Good Luck!
 
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Discussion Starter #13
Wow dmfdmf - Thanks for all that great analysis! I'm hoping Suzuki will come through with a fix for me, but I must admit that I'm a bit suspicious about the corrupt file issue too...

As suggested, I did send a message to BoosterPlug. I received a very thoughtful response that had a lot of the same information that dmfdmf explained.

Jens reply included the following:
4000 RPM steady throttle is on the border where the ECU will usually transfer to closed loop operation mode, so I can not promise that the BoosterPlug can fix the surging issue 100% on your bike.

Still: 4000 RPM steady throttle is a “low throttle opening” condition, so I’m confident that the BoosterPlug will improve things, but if the surging is also taking place in the closed loop area where the BoosterPlug is inactive, our solution will only be able to cure the open loop part of the problem.

(Closed loop surging is mostly a bitchy problem to get rid of without major changes to the fuel injection system…….)
 
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