Turbo 'flutter' during low rpm / high gear acceleration...
- Thread starter pfbz
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John Miller
New member
Thanks. I don't know it is "solved," but will know more after 5 or 10 more commutes.
I think it is possible that it is downshifting perfectly at most speeds but that there is a small window where it just needs to downshift a hair faster. I'm not married to that idea though - I need to drive it more.
According to Torrie, the downshift calculation is a function of output shaft speed to throttle position. So, if I do find a window in MPH that needs adjustment, I'll need to data log to find the OSS and actual throttle angle for him.
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I think it is possible that it is downshifting perfectly at most speeds but that there is a small window where it just needs to downshift a hair faster. I'm not married to that idea though - I need to drive it more.
According to Torrie, the downshift calculation is a function of output shaft speed to throttle position. So, if I do find a window in MPH that needs adjustment, I'll need to data log to find the OSS and actual throttle angle for him.
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Keeping in mind that much as we like accuracy, electromechanical interaction means there will be a range you'd need to work with, rather than a fixed point set in stone. For example, you may be seeing a decay in sensor function over time that forces periodic tune adjustment. May not be in the best interests of longevity eitherJohn Miller said:
That said, def looking forward to seeing how much fine control we have over the SHO
It's been a week with my final revision from my tune from Torrie and I have noticed mine doing the same thing. checked all the hardware checks stated earlier, so I'm guessing I'm going to have to email Torrie as well and see if it will fix mine. I'll report back after I find out something. great thread btw.
John Miller
New member
It's going to take some trial and error.
I confirmed this afternoon that it must use different shift tables when you activate the cruise control - my early downshift disappears with cruise activated.
I'm still going to give it some time - I want to confirm whether there are any speeds that I still need a little earlier downshift (to avoid the flutter) and do the OSS logs. Once that is done, I'm hoping Torrie can figure out which table(s) are for cruise and mirror the "perfected" shift parameters there.
Just gonna take time and patience. Thanks, Ford. After all, the car was so cheap, we should expect to have to find our own answers, right?
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I confirmed this afternoon that it must use different shift tables when you activate the cruise control - my early downshift disappears with cruise activated.
I'm still going to give it some time - I want to confirm whether there are any speeds that I still need a little earlier downshift (to avoid the flutter) and do the OSS logs. Once that is done, I'm hoping Torrie can figure out which table(s) are for cruise and mirror the "perfected" shift parameters there.
Just gonna take time and patience. Thanks, Ford. After all, the car was so cheap, we should expect to have to find our own answers, right?
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http://www.focusst.org/forum/focus-st-performance/10369-turbo-flutter.html
"This is from Braden over at Cobb:
Normal, completely. The design of the wastegate, and the low pressure spring in use make it difficult to control during high load, low rpm conditions. There is a LOT of VCT in action to create exhaust flow along with the boost control solenoid being driven at high duty cycle to allow for nearly instant spool on this engine. The factory tune delays the turbo response in these conditions partially to eliminate excessive load, but also to work around a poorly suited set of hardware. The noises you are hearing are a combination of valve overlap and aggressive wastegate dynamics coupled with a soft wastegate spring opening and closing the flapper as it is overloaded. Once exhaust flow is stabilized the system works extremely well and uses dynamics to keep boost levels near their targets.
As many have stated, downshifting is the best way to avoid these conditions. Generally, anything above 2500-3000rpm is OK in all gears, but starting lower than 2000rpm in 4-6th will net some interesting harmonics. None of which are caused by the bypass valve.
Cheers,
-Braden @ COBB"
"This is from Braden over at Cobb:
Normal, completely. The design of the wastegate, and the low pressure spring in use make it difficult to control during high load, low rpm conditions. There is a LOT of VCT in action to create exhaust flow along with the boost control solenoid being driven at high duty cycle to allow for nearly instant spool on this engine. The factory tune delays the turbo response in these conditions partially to eliminate excessive load, but also to work around a poorly suited set of hardware. The noises you are hearing are a combination of valve overlap and aggressive wastegate dynamics coupled with a soft wastegate spring opening and closing the flapper as it is overloaded. Once exhaust flow is stabilized the system works extremely well and uses dynamics to keep boost levels near their targets.
As many have stated, downshifting is the best way to avoid these conditions. Generally, anything above 2500-3000rpm is OK in all gears, but starting lower than 2000rpm in 4-6th will net some interesting harmonics. None of which are caused by the bypass valve.
Cheers,
-Braden @ COBB"
John Miller
New member
Interesting. But .... Is the "flutter" he refers to about a sound, and not about how the vehicle is actually running as described in this thread?
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John Miller
New member
Signature set up . . . I think.
Now, back to my question about whether the "flutter" referred to on the Focus ST site is only about a sound, or whether this "normal" behavior is also referring to the "feel" that we are getting?
Now, back to my question about whether the "flutter" referred to on the Focus ST site is only about a sound, or whether this "normal" behavior is also referring to the "feel" that we are getting?
John Miller
New member
I do, but I wanted a buffer with the gas. It's a DD, and I don't need to eek out every last HP.
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John Miller
New member
For the benefit of others suffering from this affliction, I wanted to circle back with an update . . . and probably call this solved for me. As discussed, getting the car tuned and having it gear down from 6th to 5th a bit quicker is a nice fix.
To start with, with just the tune, the issue was mitigated for me; it pulled so much more effortlessly in 6th gear anyway, it really didn't have an opportunity to go into 'flutter' very easily. I know this is the opposite of what some others experienced with tunes.
But there were some conditions in which it still fluttered. To rid of it completely, it took several iterations from Torrie on the downshifting. He tells me the downshifting is a function of output shaft speed (OSS) to throttle angle. In the end, I had to data log the car with these PIDs, along with those necessary to show the flutter, e.g. boost and wastegate. Torrie was able to see the OSS to throttle angle ratio when the car fluttered, and make it so the car would downshift directly before that event.
Even then, the first stab using this technique had an issue -- the car wouldn't go to 6th until 62 MPH. That was too high for me, as I do way too much highway driving to have the car hung in 5th at 55MPH. So, he made some more changes, and the car will go into 6th if at 54+ MPH. Even when completely off the throttle coasting from higher speeds, it will downshift to 5th when it hits 54ish, which I can live with.
And, I have been unable to get the car to flutter no matter how hard I try. As I start up an incline, if I am on the throttle light enough to avoid a downshift, it is not enough to make the car flutter. If I get on the throttle enough that it used to flutter, the car gears down to 5th instead. I'm sure it is costing me a little gas mileage. But, on my commute going 65 MPH over mountains, I am still approaching 29 MPG, so I won't complain.
Still data logging and working through a couple more quarks with the tune, but at least this bit is solved.
Side note on the cruise control: I can confirm that cruise uses the same shifting tables. I know because if I set the car on cruise control at 53 MPH, it will stay in 5th gear.
But, interestingly, the computer does everything it can to avoid downshifting to 5th when I set the cruise to 54+. Even if I set the cruise on 56 MPH and go up a mountain, the cruise is on the gas so light that it won't gear down. If I am driving without cruise, it is really, really tough for me to not progress the throttle at that speed (to compensate for the hill) without making it gear down. But, the cruise somehow does it. I can't complain though -- it still manages to keep speed (thanks to the power from the tune) while not hitting the throttle hard enough to flutter.
Bottom line, it is my theory that cruise uses the same shift tables, but the computer adjusts its throttle usage accordingly as to avoid downshifting if at all possible. Just a theory.
To start with, with just the tune, the issue was mitigated for me; it pulled so much more effortlessly in 6th gear anyway, it really didn't have an opportunity to go into 'flutter' very easily. I know this is the opposite of what some others experienced with tunes.
But there were some conditions in which it still fluttered. To rid of it completely, it took several iterations from Torrie on the downshifting. He tells me the downshifting is a function of output shaft speed (OSS) to throttle angle. In the end, I had to data log the car with these PIDs, along with those necessary to show the flutter, e.g. boost and wastegate. Torrie was able to see the OSS to throttle angle ratio when the car fluttered, and make it so the car would downshift directly before that event.
Even then, the first stab using this technique had an issue -- the car wouldn't go to 6th until 62 MPH. That was too high for me, as I do way too much highway driving to have the car hung in 5th at 55MPH. So, he made some more changes, and the car will go into 6th if at 54+ MPH. Even when completely off the throttle coasting from higher speeds, it will downshift to 5th when it hits 54ish, which I can live with.
And, I have been unable to get the car to flutter no matter how hard I try. As I start up an incline, if I am on the throttle light enough to avoid a downshift, it is not enough to make the car flutter. If I get on the throttle enough that it used to flutter, the car gears down to 5th instead. I'm sure it is costing me a little gas mileage. But, on my commute going 65 MPH over mountains, I am still approaching 29 MPG, so I won't complain.
Still data logging and working through a couple more quarks with the tune, but at least this bit is solved.
Side note on the cruise control: I can confirm that cruise uses the same shifting tables. I know because if I set the car on cruise control at 53 MPH, it will stay in 5th gear.
But, interestingly, the computer does everything it can to avoid downshifting to 5th when I set the cruise to 54+. Even if I set the cruise on 56 MPH and go up a mountain, the cruise is on the gas so light that it won't gear down. If I am driving without cruise, it is really, really tough for me to not progress the throttle at that speed (to compensate for the hill) without making it gear down. But, the cruise somehow does it. I can't complain though -- it still manages to keep speed (thanks to the power from the tune) while not hitting the throttle hard enough to flutter.
Bottom line, it is my theory that cruise uses the same shift tables, but the computer adjusts its throttle usage accordingly as to avoid downshifting if at all possible. Just a theory.
John Miller
New member
Final update from me:
Issue solved. Solution? Livernois.
Torrie's tune definitely helped 90%. With the quicker downshift, I could not make it flutter ever when driving it without cruise. The car would simply downshift to 5th before I could get to the throttle position necessary to make it flutter under every conceivable condition. I was generally happy with that.
However, after some more playing with it, it would still sometimes flutter with the cruise on. In my earlier post, I thought it wouldn't flutter with cruise, but it did eventually. Since the car would never downshift to 5th with cruise on, setting the cruise between 60 and 68 MPH would bring on the flutter on certain inclines. Torrie was great getting the downshift where I needed it when driving manually, and he made an effort to try and get that quicker downshift with the cruise on, but couldn't make it happen. I had more or less decided to live with it.
On a whim, I called Livernois. Anthony was somewhat non-committal about whether their tune would fix this particular issue, but stated he was "confident" it would solve it or mitigate it. After a talk with management, he agreed to give me a one time "hassle free" return of the tuner if it didn't solve the problem -- putting me at no risk. I was still hesitant that it was worth my time, so I procrastinated a couple weeks, but I eventually broke out the credit card and spend the 600 smackers. Installed the V10 93 octane tune, then eventually moved over to the 'soft shift' version of it (personal preference).
Livernois' tune fixed the flutter completely, and that is without a quicker 6 to 5 shift that we were previously using to mask the issue. I just took a 600 mile trip over that last 2 days, and tried every conceivable speed, incline, and condition to the flutter, and it ain't there. Even with cruise tried every way I could.
I am so happy I gave them a shot, and I feel like I can enjoy my commute again. I guess there really is something to their claim of adjusting parameters within the tune that no one else does. On a side note, I find their tune less "explosive" than the tunes from Unleashed, but it is smoother, especially at lower RPMs. Since this is a DD, that works just fine for me.
Nothing against Torrie -- his tune was otherwise fun, and he was very responsive with his updates. In fact, I was on revision 10 from Torrie trying to chase down this issue before going the Livernois route, so I would certainly recommend his tunes if you don't have the same condition from which I was suffering.
Issue solved. Solution? Livernois.
Torrie's tune definitely helped 90%. With the quicker downshift, I could not make it flutter ever when driving it without cruise. The car would simply downshift to 5th before I could get to the throttle position necessary to make it flutter under every conceivable condition. I was generally happy with that.
However, after some more playing with it, it would still sometimes flutter with the cruise on. In my earlier post, I thought it wouldn't flutter with cruise, but it did eventually. Since the car would never downshift to 5th with cruise on, setting the cruise between 60 and 68 MPH would bring on the flutter on certain inclines. Torrie was great getting the downshift where I needed it when driving manually, and he made an effort to try and get that quicker downshift with the cruise on, but couldn't make it happen. I had more or less decided to live with it.
On a whim, I called Livernois. Anthony was somewhat non-committal about whether their tune would fix this particular issue, but stated he was "confident" it would solve it or mitigate it. After a talk with management, he agreed to give me a one time "hassle free" return of the tuner if it didn't solve the problem -- putting me at no risk. I was still hesitant that it was worth my time, so I procrastinated a couple weeks, but I eventually broke out the credit card and spend the 600 smackers. Installed the V10 93 octane tune, then eventually moved over to the 'soft shift' version of it (personal preference).
Livernois' tune fixed the flutter completely, and that is without a quicker 6 to 5 shift that we were previously using to mask the issue. I just took a 600 mile trip over that last 2 days, and tried every conceivable speed, incline, and condition to the flutter, and it ain't there. Even with cruise tried every way I could.
I am so happy I gave them a shot, and I feel like I can enjoy my commute again. I guess there really is something to their claim of adjusting parameters within the tune that no one else does. On a side note, I find their tune less "explosive" than the tunes from Unleashed, but it is smoother, especially at lower RPMs. Since this is a DD, that works just fine for me.
Nothing against Torrie -- his tune was otherwise fun, and he was very responsive with his updates. In fact, I was on revision 10 from Torrie trying to chase down this issue before going the Livernois route, so I would certainly recommend his tunes if you don't have the same condition from which I was suffering.
I highly doubt its due to something they can change that others cant but more likely due to someone not knowing how to make an adjustment.
Its not something lms changes but more likely something torrie does that is having an adverse effect.
Wastegate duty cycle modifiers is the culprit if i had to bet , and i dont gamble
I could go into more detail but im not at liberty to do so
Great job informing the community though
Its not something lms changes but more likely something torrie does that is having an adverse effect.
Wastegate duty cycle modifiers is the culprit if i had to bet , and i dont gamble
I could go into more detail but im not at liberty to do so
Great job informing the community though
John Miller
New member
Well, remember this problem occurred stock for me, and others in this thread (and in other threads I found) also said it happened stock. So, it's not a problem created by the aftermarket tunes, Torrie or otherwise.
I read at least two others say it was worse with a tune. Though the additional power of Torrie's tune changed the MPH at which the flutter would occur for me, and though the quicker downshift made it only happen for me with the cruise on, it was worse with a tune when it did happen. I presume because boost and other power-making conditions only exacerbate the sensation.
But, again, nothing with Livernois. I can't say what they did differently, obviously. And, I'm positive it was nothing "on purpose." Whatever they did and for whatever reason, the issue doesn't exist with their tune.
I read at least two others say it was worse with a tune. Though the additional power of Torrie's tune changed the MPH at which the flutter would occur for me, and though the quicker downshift made it only happen for me with the cruise on, it was worse with a tune when it did happen. I presume because boost and other power-making conditions only exacerbate the sensation.
But, again, nothing with Livernois. I can't say what they did differently, obviously. And, I'm positive it was nothing "on purpose." Whatever they did and for whatever reason, the issue doesn't exist with their tune.