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I'm still confused about the fuel cut on decel issue


D.A.

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On 7/13/2020 at 1:19 PM, topazsparrow said:

I've never ridden an FZ-07 with bad throttle response or mappings.

I think people are blowing it out of proportion a bit and confusing throttle mapping with the heavy engine braking when rolling off throttle. As mentioned, Injector cut for emissions is the reason for that nonsense. ...

 

On 7/13/2020 at 1:25 PM, DewMan said:

I'm not agreeing or disagreeing with you. 

I'm only giving you my opinion of when I first got the FZ-07. The off-throttle fuel cut-off scared me with how it unsettled the bike more than once. ...

I lifted the quotes above from another thread wherein folks were discussing whether or not the FZ/MT-07 is a good beginner bike. (My thanks to @topazsparrow and @DewMan for inspiring my new thread!) (BTW my opinion is it's not a good beginner bike.)

I realize this topic has been discussed ad nauseam on the forum but I am still confused about how to tame my FZ-07's jerkiness at small throttle openings. This one annoying quirk makes the FZ, which is by far the least powerful motorcycle I've ever owned, the most dangerous bike I've ever ridden. I call it dangerous because, no matter how gingerly I finesse the throttle, I never know when I'm going to lose traction while leaned way over in a corner and getting on the gas.

I've looked at all the aftermarket and flashing options (2WDW, PCV, BoosterPlug, etc.), started a few posts about the topic and talked to vendors about their solutions and while I appreciate everyone's input, thus far feel like no one has directly addressed my specific concern, which is: Why, when I'm at a dead stop and I ever-so-gently roll on the throttle, does the bike accelerate super-smoothly and predictably for the first 30 feet or so, then, Bam! jolt forward with a suspension-upsetting and confidence-destroying burst of thrust? And how, with surgical precision, do I eliminate this one problem – which is prone to occur in every gear – without affecting anything else about the bike's character, which I otherwise love?

Performance-wise, my bike is 100% stock. I'm not looking to up the horsepower or torque. In stock form it has plenty of oomph for the way I ride it. (Plus if having a faster machine was my priority, I would buy something with a bigger engine or would have kept one of my liter bikes.) I'm not interested in aftermarket pipes or modifying the air box. (But I don't begrudge any of you that have gone that route!)

A CPU flash seems like the most logical way to attack the problem but that option apparently hinges on eliminating the fuel-cut-on-decel that was programmed-in by the factory. What doesn't make sense to me about that strategy is the jerkiness occurs when accelerating from a stationary position, before there has been any deceleration, so how can cutting fuel on decel cure a snatchy throttle issue that appears the first time I accelerate?

I realize rolling off the throttle abruptly when moving fast causes the engine to brake hard and the front end to dive, and getting back on the gas too quickly makes the bike jerk forward, but aren't those really two discrete phenomena working in unison rather than a single issue?

The other aspect to this is that I LOVE THE 07'S ENGINE-BRAKING just the way it is and hate to lose or even decrease it. Yet if my understanding is correct, if I go with a CPU flash but opt NOT to have the fuel-cut-on-decel disabled, I may still end up with the off-to-on-throttle twitchiness I hope to eliminate.

What am I missing?

Here's a simple graphic I created that shows what happens when I accelerate from a standstill vs. what I would like to have happen:

 

D.A._THROTTLE_POSITION_GRAPH_072920B.jpg

Edited by D.A.
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I think there are two different issues you're describing.

The fuel decel cut affects the fuelling/throttle feel when going from closed throttle to very small throttle openings - I used to experience it typically when rolling up (closed throttle) to a tight roundabout, small throttle to get around it and it would upset the balance of the bike a bit. It was a bit unnerving at first but I eventually got used to it.

The issue you're describing taking off from a stop sounds like its related to the stock fuel map. The only way around this is is to change it via an ecu tune/PCV etc.

I have a PCV fitted now and don't really have either of the issues you describe.

I'm sure others will have more to add.

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As above, what you're describing is not the decel cut but the map.  I noticed it, too, have no idea why Yamaha did that.  2WDW made the problem go away with their standard flash and left me with what I consider sufficient engine braking.  You can no doubt get them to leave the decel cut in if you really like it, and will probably be able to take it out if you change your mind.

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topazsparrow
7 hours ago, stickshift said:

I think there are two different issues you're describing.

The fuel decel cut affects the fuelling/throttle feel when going from closed throttle to very small throttle openings - I used to experience it typically when rolling up (closed throttle) to a tight roundabout, small throttle to get around it and it would upset the balance of the bike a bit. It was a bit unnerving at first but I eventually got used to it.

The issue you're describing taking off from a stop sounds like its related to the stock fuel map. The only way around this is is to change it via an ecu tune/PCV etc.

I have a PCV fitted now and don't really have either of the issues you describe.

I'm sure others will have more to add.

There's certainly something else going on here for sure.

Either the TB's are out of sync or maybe OP isn't as good with the clutch as he thinks (or its misbehaving). If the bike is running properly, the stock fuel maps do NOT behave that way - particularly when everything else on the bike is stock. At least none of the ones I've ever ridden here in Canada.

Engine braking aside, I'd almost put money on it being TB Syncing or Fuel/Air delivery related (Just not the ECU). I'm making the assumption that after 30 feet when OP gets jolted, he's no longer on the clutch at all.

I didn't see OP say if he synced his TB's yet.

Edited by topazsparrow
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11 hours ago, stickshift said:

I think there are two different issues you're describing.

The fuel decel cut affects the fuelling/throttle feel when going from closed throttle to very small throttle openings - I used to experience it typically when rolling up (closed throttle) to a tight roundabout, small throttle to get around it and it would upset the balance of the bike a bit. It was a bit unnerving at first but I eventually got used to it.

The issue you're describing taking off from a stop sounds like its related to the stock fuel map. The only way around this is is to change it via an ecu tune/PCV etc.

I have a PCV fitted now and don't really have either of the issues you describe.

I'm sure others will have more to add.

 

12 hours ago, D.A. said:

 

I lifted the quotes above from another thread wherein folks were discussing whether or not the FZ/MT-07 is a good beginner bike. (My thanks to @topazsparrow and @DewMan for inspiring my new thread!) (BTW my opinion is it's not a good beginner bike.)

I realize this topic has been discussed ad nauseam on the forum but I am still confused about how to tame my FZ-07's jerkiness at small throttle openings. This one annoying quirk makes the FZ, which is by far the least powerful motorcycle I've ever owned, the most dangerous bike I've ever ridden. I call it dangerous because, no matter how gingerly I finesse the throttle, I never know when I'm going to lose traction while leaned way over in a corner and getting on the gas.

I've looked at all the aftermarket and flashing options (2WDW, PCV, BoosterPlug, etc.), started a few posts about the topic and talked to vendors about their solutions and while I appreciate everyone's input, thus far feel like no one has directly addressed my specific concern, which is: Why, when I'm at a dead stop and I ever-so-gently roll on the throttle, does the bike accelerate super-smoothly and predictably for the first 30 feet or so, then, Bam! jolt forward with a suspension-upsetting and confidence-destroying burst of thrust? And how, with surgical precision, do I eliminate this one problem – which is prone to occur in every gear – without affecting anything else about the bike's character, which I otherwise love?

Performance-wise, my bike is 100% stock. I'm not looking to up the horsepower or torque. In stock form it has plenty of oomph for the way I ride it. (Plus if having a faster machine was my priority, I would buy something with a bigger engine or would have kept one of my liter bikes.) I'm not interested in aftermarket pipes or modifying the air box. (But I don't begrudge any of you that have gone that route!)

A CPU flash seems like the most logical way to attack the problem but that option apparently hinges on eliminating the fuel-cut-on-decel that was programmed-in by the factory. What doesn't make sense to me about that strategy is the jerkiness occurs when accelerating from a stationary position, before there has been any deceleration, so how can cutting fuel on decel cure a snatchy throttle issue that appears the first time I accelerate?

I realize rolling off the throttle abruptly when moving fast causes the engine to brake hard and the front end to dive, and getting back on the gas too quickly makes the bike jerk forward, but aren't those really two discrete phenomena working in unison rather than a single issue?

The other aspect to this is that I LOVE THE 07'S ENGINE-BRAKING just the way it is and hate to lose or even decrease it. Yet if my understanding is correct, if I go with a CPU flash but opt NOT to have the fuel-cut-on-decel disabled, I may still end up with the off-to-on-throttle twitchiness I hope to eliminate.

Have you unplugged your O2 sensor and went for a ride?  Give it a shot.  You'll be surprised:  It'll go like a raped-ape, but your mileage is history.  Sorry I don't have a better solution, but there's a good chance the twitchiness you're experiencing will disappear.  Please post what you discover.

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Thank you for the responses!

@stickshift and @timjh: It does sound like I am confusing the overlapping effects caused by a lean fuel map with fuel being cut on deceleration. I'm just not sure where one begins and the other ends.

@topazsparrow: Throttle body sync was right on the money when I checked it at 6000 miles about 4 months ago so I doubt that's involved. And yes, by the time I feel the power surge, I will have already let go of the clutch handle. My first inclination was to think my bike is the anomoly. But once I started reading more about the subject on this forum, I realized lots of other riders have experienced the same issue.

In my opening post I described how the power gets snatchy when I start out from a stop but that was specifically to make the point it occurs before I ever have a chance to decelerate. Therefore it shouldn't be related to fuel-cut-on-decel being enabled or disabled.

The snatchiness is there when I first accelerate. But it reappears anytime I roll off the throttle and get back on the gas. It happens in any gear (although it is most noticeable in the lower 3 gears). It is not speed dependent or RPM dependent. It seems to be based solely on how far I have the throttle grip twisted: from totally closed up to about 15% open, acceleration is super-smooth; at around 15% open there's a sharp increase in power; and from 16%-100% it's smooth sailing again (as illustrated in the chart I uploaded in my initial post).

I have always subscribed to the mantra, "Don't blame the bike. The bike isn't twitchy. The rider is twitchy," and since buying the FZ in February I have been able to find workarounds, like being absurdly smooth with the throttle or feathering power with the clutch any time I am near that 15% zone.

But I've decided it's time to go ahead and blame the bike and find a solution. I just need to pull the trigger on one of the many fixes available and check the results for myself.

Oh!... there is one good thing about the surge: it makes it extremely easy to power wheelie!

@rfmueller: Your post popped up just as I was about to hit SUBMIT REPLY. I will try your suggestion about pulling the O2 sensor. Very interested to see what effect that has. Thanks!

Edited by D.A.
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The throttle response is part of the character of this bike, I was mighty impressed with the throttle response when I first rode it.

Do you have the standard throttle tube fitted? Any quicker turn throttle (R6 etc) will make it snatchier.

It might be worth trying to get a ride on another 07 to see if it behaves the same as yours (I suspect it will).

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34 minutes ago, stickshift said:

The throttle response is part of the character of this bike. ...

... Any quicker turn throttle (R6 etc) will make it snatchier...

True! Could turn out I tame the beast but dislike it neutered. 
 

And yeah, the plot thickens: I do have the R6 throttle grip/tube. Installed it several months ago knowing it would exacerbate the problem, which it did — but only ever so slightly. After comparing the two I felt the advantages of the R6 tube outweighed the minor increase in sensitivity. 

Edited by D.A.
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  • 2 weeks later...
On 7/30/2020 at 4:17 PM, rfmueller said:

... Have you unplugged your O2 sensor and went for a ride?  Give it a shot.  You'll be surprised:  It'll go like a raped-ape, but your mileage is history.  Sorry I don't have a better solution, but there's a good chance the twitchiness you're experiencing will disappear.  Please post what you discover.

@rfmueller: I finally had a chance to unplug the O2 sensor and test drive my FZ.

I did not detect any reduction in the jerkiness that occurs at closed-to-small throttle openings. In fact, I did not notice any change whatsoever in the bike's performance, regardless of road speed, RPM or throttle position. My assumption is that disconnecting the O2 sensor simply prevented the bike from going into closed loop mode, meaning the ECU never received any feedback from the sensor regarding oxygen content in the exhaust system and therefore never leaned out the AFR when operating at steady throttle openings. So, the net effect was most likely the engine gulped down more fuel than necessary whenever I was cruising along at a relatively constant speed.

But it was a fun experiment and I appreciate the suggestion!

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Thanks for the feedback.  I'm surprised by the results; that is very strange.  My bike was different.  What about the possibility of a dead spot in your throttle position sensor? Yours sounds too consistent, but it's still possible.  That is only an unlikely guess, but would also cause the jerkiness.  With the engine off, it's possible to clear that sensor off by opening and closing your throttle very quickly a whole bunch of times:  The sensor wiper might knock off any debris.  If you have a DVM you can measure that sensor and find out what the resistance is while turning the throttle (engine off).  It could continually increase or decrease resistance as you change throttle position.  If you have a dead spot, your meter will go to either show an open or a short while moving the throttle.

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My bike is stock tuned and when I snap the throttle there is no hesitation just the front wheel coming up.

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I read the stuff here, but probably not thorough enough.  Just a question and a point...

I take it the problem is on decel the EFI shuts off fuel supply to a point when the throttle is totally closed, then there is a bit of a "clunkiness" when opening throttle again at lower rpm.  Is that it?    I know my XSR shuts down at least noticeably in any gear over 2nd (I am seldom in a throttle off decel in 2nd or 1st).   I also know my old Ranger truck does pretty much the same thing in 3rd, 4th, and 5th gears.  You can actually feel it come back on when the rpm drops to a point where it would stall out if the clutch was disengaged, clearly an electronic setting.

Point -  in my riding I never really shut completely off and apparently don't run into this fuel shut off if that is what it is.   I do realize the 700 isn't the smoothest of engines in transitions at lower rpm and requires smooth throttle use to maintain smooth operation.  If I'm sloppy the bike acts sloppy, if I'm smooth I can click through gears like an automatic transmission.  

Either way, is it the EFI shuts off when throttle is full off?

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On 8/12/2020 at 4:21 PM, rfmueller said:

... it's possible to clear that sensor off by opening and closing your throttle very quickly a whole bunch of times:  The sensor wiper might knock off any debris.  If you have a DVM you can measure that sensor and find out what the resistance is while turning the throttle ...

@rfmueller: Thanks for the additional troubleshooting ideas! I'll have to hold off on trying them, though, since I removed my ECU yesterday and shipped it to 2WDW. I figured it was time to try the re-flash approach since that seems to have solved the small throttle opening jerkiness problem for a lot of other FZ-07 owners. I will post the verdict once the ECU returns.

 

On 8/13/2020 at 3:05 PM, Grant31781 said:

My bike is stock tuned and when I snap the throttle there is no hesitation just the front wheel coming up.

@Grant31781: Yep! My bike does the same thing when I snap open the throttle. The jerkiness I'm concerned with, however, is primarily noticeable when the throttle is closed and I try to finesse it open super-slowly and super-smoothly. Once I reach the point where the throttle is partially open the bike gets a momentary jerk of power then resumes accelerating smoothly and predictably. The problem is the jerk happens no matter how smoothly or slowly I twist the throttle. It's not an issue if I'm accelerating balls out in a straight line or trying to do a power wheelie but it is dangerous if I'm leaned over in a tight turn and inadvertently let the throttle close because when I start to get back on the gas, still leaned over, a sudden surge of power can make the rear tire spin / lose traction and potentially cause a low-side.

 

On 8/14/2020 at 1:34 AM, pgeldz said:

You could always go with Rapid Bike. ...

@pgeldz: Interesting suggestion! I will look into that option if the 2WDW flash doesn't bear fruit.

 

18 hours ago, klx678 said:

... I take it the problem is on decel the EFI shuts off fuel supply to a point when the throttle is totally closed, then there is a bit of a "clunkiness" when opening throttle again at lower rpm.  Is that it? ...

@klx678: That is partially accurate in that it does happen if I'm on the gas, close the throttle and get back on the gas again. However, I don't believe it's solely related to fuel being cut on deceleration because the jerkiness also happens when I've just started out from a stop, am accelerating and have not yet decelerated. In other words, it can't be caused by lack of fuel on deceleration when no deceleration has occurred yet.

Sure, the anomaly could be due to user error but I doubt that's the answer since I've been riding motorcycles since 1973, have owned many, many bikes in multiple genres and this is the first time I've experienced a bike with this particular problem. The fueling on my previous motorcycles has been much smoother, in spite of the fact most of my previous bikes have had much more powerful engines than the FZ-07's. If the issue I have been describing were happening on your bike, I doubt there is any way you could not notice it. It is very light switch-like.

I've had a few conversations with Nels at 2WDW about this subject. He corroborates what @stickshift and @timjh stated above, that the snatchy throttle I describe is very common with the recent crop of fuel-injected bikes, including the FZ/MT-07, and claims it is due to the combined effects of both lean fueling at small throttle openings and fuel being cut on deceleration. As I understand it, the two factors overlap in such a way that they exacerbate a problem that would be less noticeable if only one of the two conditions existed.

Apparently the only way to eliminate the jerkiness completely is to re-map / enrich the fueling at small throttle openings AND defeat the fuel-cut-on-decel mode. The former can be accomplished with many different piggyback devices but the latter only by reprogramming the ECU. So I decided to go with the flow and follow the crowd to 2WDW and have Nels flash my ECU.

If that doesn't work then it's back to the drawing board!

 

 

Edited by D.A.
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The Jerkiness and deadspotting is 100% stock tune. It's just more apparent for some FZ owners due to the location they live in IE altitude, temperature, humidity etc as these variables can amplify those issues more than it would for someone else.

What I found was I richened the 0% throttle range in my PCV from 2000RPM up to limiter by 3 fuel trim to combat decel backfiring and to ease the engine braking slightly and I mean it decreased it slightly it's still definitely there. I then had to richen the off idle transition of the map in the 2% 5% and 10% ranges of the map and it almost completely removed the snappiness between gear shifts or simply rolling off the throttle then rolling back into it while staying in the same gear.

18 hours ago, klx678 said:

Either way, is it the EFI shuts off when throttle is full off?

 From my understanding of it when you let off the throttle while riding the EFI doesn't necessarily shut off but it isn't sending fuel into the engine when decelerating at 0% throttle position. So when you are decelerating at 0% throttle and then you pick the throttle back up, the engine gets a burst of fuel and that's when the bike snaps forward. So by adding fuel on decel at 0% (or disabling decel inj cut in an ECU flash) you still have fuel flowing into the engine at all times and it helps lessen that jerk when you pick the throttle back up. Hope that makes sense.👍

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Thanks for answering my question about the stock situation..

When zero fuel is sent, that's pretty much shut off now, isn't it.     I  would think holding the throttle slightly open keeps the fuel flow, which is what I do.

I will say I do that for a couple reasons, on the KLX650 it will help keep the rear wheel turning instead of locking up and stalling under braking on rough loose surfaces where the tire may lose traction and lock when the brake is being applied - kinda power braking.  It also cuts a bit of the popping on the overrun under decel.  So I kind of have the habit.  Maybe that's why I don't really encounter the problems some are having.  I never really shut down completely on throttle out of habit.

Either way, I guess I understand, lean lower rpm fueling for EPA/DOT and that in the upper gears the EFI goes to zero fuel mix again for EPA/DOT reasons.

I also may not encounter the problem because I'm riding "the pace" as opposed to a bit more track oriented or actual track riding.  Not knocking it in some conditions, just saying I don't do that, my kicks are on the dual sport, sliding around on the gravel roads,. and smoother quick secondary highway/back road riding at reduced pace.

 

Edited by klx678
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Sounds like you have something going on with the mapping or fueling. Unplug the ECU and plug it back in and see if that helps. Might be a loose connection somewhere. Look up how to remove and send that unit to 2WDW for a flash. Just don;t take it off. Unplug it and make sure the connection looks OK and that you plug it back in securely and then see what happens. Won't cost anything but an hour of your time. You could try that with any other connection you find on the fueling system.

Has your bike always done that or did it just start doing it one day?

 

Edit - Nevermind. Just seen you sent the ECU to them. Good luck.

Edited by michigan400
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@michigan400: Yep, I mailed the ECU to 2WDW last week, they’ve received it and said they’ll flash and ship back to me today. But I nonetheless appreciate your input!

Incidentally, before mailing I did unplug, spray-clean and reconnect the ECU a couple of times, test riding the bike after each connection. There was no discernible change in the bike’s behavior. And to answer your other question, the bike has had jerky fueling since the day I bought it. I did buy it used, though, but the original owner made no performance-related alterations to it. 

I don’t think there’s anything extraordinary or atypical about my bike’s twitchy throttle. Based on what I’ve read on this forum, it seems a lot of other owners have experienced the exact same phenomenon. My confusion — and my impetus for starting this thread — was about how to best solve the problem. 

Many people on here maintain the issue is primarily a result of fuel being cut on deceleration but that answer never seemed logical to me because even though the twitchiness does occur when you roll off the throttle then get back on the gas again, it also occurs when you first start up the bike, roll on the gas, let out the clutch and reach about 2300 rpm. Meaning, it happens before the bike has ever decelerated. And if the jerkiness can occur before you decelerate, it cannot plausibly be caused by fuel being cut on deceleration.

I also find that answer frustrating because I like my stock FZ’s engine braking just the way it is and prefer not to have it diminish.

I’ve always known it was a fueling issue of some sort but have been hoping to determine EXACTLY where the issue originates so I can troubleshoot it effectively — not just come up with a workaround. Unfortunately the best answer I’ve been able to find is that the bike is twitchy at small throttle openings because of the overlapping effects of lean fuel mapping and fuel-cut-on-decel. I’m not entirely satisfied with that answer but unless I buy a Dyno and a Flash Tune harness and develop the skills to use them, I’m not sure I’ll ever get a better answer. 

So, I decided to stop resisting and go with the flow by having the ECU reflashed. If this approach successfully eliminates the issue, I can stop obsessing over it. If not, the search will continue!

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6 hours ago, D.A. said:

I also find that answer frustrating because I like my stock FZ’s engine braking just the way it is and prefer not to have it diminish.

I’ve always known it was a fueling issue of some sort but have been hoping to determine EXACTLY where the issue originates so I can troubleshoot it effectively — not just come up with a workaround. Unfortunately the best answer I’ve been able to find is that the bike is twitchy at small throttle openings because of the overlapping effects of lean fuel mapping and fuel-cut-on-decel. I’m not entirely satisfied with that answer but unless I buy a Dyno and a Flash Tune harness and develop the skills to use them, I’m not sure I’ll ever get a better answer. 

So, I decided to stop resisting and go with the flow by having the ECU reflashed. If this approach successfully eliminates the issue, I can stop obsessing over it. If not, the search will continue!

I am really interested to hear your impressions to see if they also echo what most others say. I am 99% sure I will go this route but I think I am going to hold out to see if there is a sale later in the year. For me the main thing I want to eliminate is the off/on snap that only happens occasionally. 

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@seven: Not sure if you realize it or not but 2WDW has a sale going on right now. The normal price on their mail-in ECU flashing service is apparently $315 but you can get it for $249.99 if you enter code “covid-19” at checkout. I searched the archives for 2WDW specials before pulling the trigger and $249 was lower than any other price mentioned. 

Edited by D.A.
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@D.A. The route I am going will be to get the FTEcu On-bike Tuner and then grab just the tune from 2WDW as I live in Canada and don't want to deal with cross border shipping...plus then I can play with different tunes as I change stuff on the bike.

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5 hours ago, D.A. said:

@seven: Good plan! How much does it cost to buy the tune file?

They quoted me $150 for just the tune.

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