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Discussion Starter · #1 ·
I've read a lot of comments on the 3rd gear hesitation, and I thought I would post my thought. On the one hand, I do think 3rd gear is too tall, but that is a separate matter. I'm talking about the part where it seems like there is a "weak spot" in the rpm band in 3rd gear because engine acceleration slows.

While it sounds odd, and looks odd if you're watching the tach, I don't think it's really a big deal. I'm pretty sure that "weak spot" is just caused by the torque converter locking. The engine seems to bog down because the tranny is slipping less. If you watch the actual speed, though, you are still accelerating, even if the rpms aren't. The tranny is just increasing it's effective gear ratio as the TC allows less slip.

Think of it like a bike on ice. You can pedal fast, but you aren't accelerating as fast as you should be, considering how fast you are pedaling. That's the tranny "slipping". Then, you catch traction and you suddenly can't pedal as fast, but you are accelerating faster. That's the torque converter locking.

Obviously the torque converter isn't allowing as much slippage as the bike on ice, but you get the idea. Just because the RPMs aren't accelerating doesn't mean the car isn't.
 
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Discussion Starter · #2 ·
I will verify this theory once I get my SCT X4 to datalog.
 

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Actually I think its an artificial limit Ford put into the cars. Last time at the drag strip when I was talking with a SHO owner, at least on their 3.5 Ecoboost motors, they were programmed to dump boost heavily in third gear for some reason. He said with a stock tune his SHO would be crossing the finish line with 4-6 PSI. Its probably done to slow the car down and keep it in the performance market where Ford wants it, above the V6 Mustang and below the V8 Mustang.
 

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I've noticed that the "week spot" in third is still there, but much less noticeable after increasing the od of the tire with the snows. It's just under an inch, but you feel it. Or maybe it's just the noisy tires!
 

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Don't think it's the torque converter... according to the shop manual the torque converter only is allowed to lock up in 4th,5th, and 6th gear. The gear ratios are 4.48 first 2.87 second 1.84 third 1.41 forth 1 to 1 in fifth and 0.74 in sixth. So technically the drop from first to second is more dramatic than 2nd to 3rd so not sure why the stock tune feels so bad second to third. 2nd to 3rd is much improved with a tune so must be more in the
programming than anything but that's kinda a general evaluation of what my experience has been.
 

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Discussion Starter · #6 ·
Don't think it's the torque converter... according to the shop manual the torque converter only is allowed to lock up in 4th,5th, and 6th gear. The gear ratios are 4.48 first 2.87 second 1.84 third 1.41 forth 1 to 1 in fifth and 0.74 in sixth. So technically the drop from first to second is more dramatic than 2nd to 3rd so not sure why the stock tune feels so bad second to third. 2nd to 3rd is much improved with a tune so must be more in the
programming than anything but that's kinda a general evaluation of what my experience has been.
I think what you are talking about is the tall gear ratio. I'm talking about the "dead spot" in third where it seems to bog for a moment, usually in the middle of the RPM band. I don't think the torque converter is neccessarily locking, but I think that's where is tightens up for some reason. Even when I'm not getting on it I can feel it doing that, and that's when I actually feel the car surge forward a bit when the RPMs bog down. That's the main reason I think its more trans related than engine related.

As for the boost dump theory, I logged a few runs when I had my SCT X4 from Amazon before I returned it, and I didn't see any boost dumps.
 

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I don't have the logs right now but it is apparent something is weird. I know it's not the boost as logs show boost is strong. Through Vbox logging it really is something that is hindering performance, even with a tune. It's like the accel pauses for a second then continues. The only way I have fixed this somewhat is a shorter shift from second into third (LMS) and checking on my latest tune update from Unleashed to see how it looks.

Looking at the stock or tuned logs you see this weird bump where the rpms just doesnt ascend like the other gears and man 3rd gear is long. My thought is torque converter locking up. I'll post some graphs and logs tomorrow so you guys can see.
 

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Discussion Starter · #8 ·
I don't have the logs right now but it is apparent something is weird. I know it's not the boost as logs show boost is strong. Through Vbox logging it really is something that is hindering performance, even with a tune. It's like the accel pauses for a second then continues. The only way I have fixed this somewhat is a shorter shift from second into third (LMS) and checking on my latest tune update from Unleashed to see how it looks.

Looking at the stock or tuned logs you see this weird bump where the rpms just doesnt ascend like the other gears and man 3rd gear is long. My thought is torque converter locking up. I'll post some graphs and logs tomorrow so you guys can see.
Does the Vbox actually show that it affects the acceleration of the car, as in Gs or MPH, or is it just the RPM bog that it shows? I'm not all that familiar with Vbox.
 

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Does the Vbox actually show that it affects the acceleration of the car, as in Gs or MPH, or is it just the RPM bog that it shows? I'm not all that familiar with Vbox.
Vbox will show affects on acceleration in MPH. The tests below show when the V1 for the Edges or "non aggressive" tune came out -



First and third graph shows the original tune for the Edge Sports. AKA non aggressive tune.... as you see the acceleration you naturally have more seconds go by from 10-20 vs 50-60 vs 90-100. So as you move across the x axis the linear progression is smooth and shouldn't have a huge jump in seconds. But as you can see, there is this weird bump in the 60-70 mph area right as you hit third gear.... interesting. As LMS tweaked the tune a bit to aggressive, it went away slightly but you can kinda still see it is there.



The above graph shows stock boost and RPM. Boost is the purple line. RPM is the jagged orange line. First and second gear you see natural stock boost progression and then you hit third and it just dips for some odd reason, it goes from 17 psi after shift, down to 12 psi, and back up to 17 psi. This is the stock dead spot in third gear IMO. Could also be a combination of the trans. too but who knows.

This actually happens still on the LMS tune but not as crazy as the stock tune. The latest Unleashed tune doesn't have a dip at all interestingly enough and dang my V10 tune is feeling good and can't wait to test :)

So are these the reasons for the dip in third, probably to some aspect, but I am not an engineer, just a data guru.

Thanks!
 

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Discussion Starter · #10 ·
Vbox will show affects on acceleration in MPH. The tests below show when the V1 for the Edges or "non aggressive" tune came out -



First and third graph shows the original tune for the Edge Sports. AKA non aggressive tune.... as you see the acceleration you naturally have more seconds go by from 10-20 vs 50-60 vs 90-100. So as you move across the x axis the linear progression is smooth and shouldn't have a huge jump in seconds. But as you can see, there is this weird bump in the 60-70 mph area right as you hit third gear.... interesting. As LMS tweaked the tune a bit to aggressive, it went away slightly but you can kinda still see it is there.



The above graph shows stock boost and RPM. Boost is the purple line. RPM is the jagged orange line. First and second gear you see natural stock boost progression and then you hit third and it just dips for some odd reason, it goes from 17 psi after shift, down to 12 psi, and back up to 17 psi. This is the stock dead spot in third gear IMO. Could also be a combination of the trans. too but who knows.

This actually happens still on the LMS tune but not as crazy as the stock tune. The latest Unleashed tune doesn't have a dip at all interestingly enough and dang my V10 tune is feeling good and can't wait to test :)

So are these the reasons for the dip in third, probably to some aspect, but I am not an engineer, just a data guru.

Thanks!
I'm not sure what to make of the Vbox data, but it looks like something is certainly off if it takes the same amount of time to get from 60-70 as it does 70-80.

For the datalog, the 3rd line is speed, I assume? If so, it looks pretty smooth to me. If there were a dead spot, there should be a flat spot in the speed line. The boost drop could be caused by any number of things. I suspect it's backing off the boost because the shift causes a spike, so it backs the boost off to compensate. That droop comes too soon after that shift IMO to be what we're noticing. Unleashed doesn't take any measures to control boost spikes from what I hear which is why there wouldn't be any droops in their tune. The only problem with that is that it can cause a droop in fuel pressure instead, which (at least in the SHO) can have a hard time recovering. That is why my plan is to do a hybrid setup that doesn't use the throttle to control boost, but vents spikes with a intake mounted wastegate that acts as a BOV when the car shifts. It makes a much more smooth boost and fuel pressure line. Apparently makes the SHO crazy fast. I'm hoping for the same result on our cars.

I'm still not convinced there is a dead spot or weak spot though. The speed is still climbing when the RPMs are bogging, so I think it's just the torque converter.

In fact, if it is what I think it is, it might actually be a smart move by Ford. By tightening the torque converter right smack in the middle of peak torque, they are increasing the effective gear ratio when the engine is making the most power. I still think it's stupid that they made 3rd gear so tall, though, because I bet that's the real reason the vbox shows those results.
 

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Discussion Starter · #11 ·
Here we go. I bought an X4 off Amazon a while back and returned it when I found out SCT didn't have support at the time. I did get a 1st-3rd gear run logged before I sent it back, though. Unfortunately I couldn't log the speed, but the stuff I did get tells a little bit of the story.

You can see that the boost and load is pegged where the flat spot in the RPM line is, which tells you that it's making full power in that spot. Even where the boost droops it's still making more boost than it make through all of 2nd gear. I'm betting that if there was a speed line, it would be pretty normal looking without any flat spots that match the RPM flat spot.
 

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I'm not sure what to make of the Vbox data, but it looks like something is certainly off if it takes the same amount of time to get from 60-70 as it does 70-80.

For the datalog, the 3rd line is speed, I assume? If so, it looks pretty smooth to me. If there were a dead spot, there should be a flat spot in the speed line. The boost drop could be caused by any number of things. I suspect it's backing off the boost because the shift causes a spike, so it backs the boost off to compensate. That droop comes too soon after that shift IMO to be what we're noticing. Unleashed doesn't take any measures to control boost spikes from what I hear which is why there wouldn't be any droops in their tune. The only problem with that is that it can cause a droop in fuel pressure instead, which (at least in the SHO) can have a hard time recovering. That is why my plan is to do a hybrid setup that doesn't use the throttle to control boost, but vents spikes with a intake mounted wastegate that acts as a BOV when the car shifts. It makes a much more smooth boost and fuel pressure line. Apparently makes the SHO crazy fast. I'm hoping for the same result on our cars.

I'm still not convinced there is a dead spot or weak spot though. The speed is still climbing when the RPMs are bogging, so I think it's just the torque converter.

In fact, if it is what I think it is, it might actually be a smart move by Ford. By tightening the torque converter right smack in the middle of peak torque, they are increasing the effective gear ratio when the engine is making the most power. I still think it's stupid that they made 3rd gear so tall, though, because I bet that's the real reason the vbox shows those results.

Yes, the 60-70 is that "flat" spot we have been talking about. You have to look carefully but you won't see the line just go flat, its not like the mph just stay there, they just don't increase over time as they would in previous rpm's and gears.

There is a weak spot, speed would climb still with a weak spot, just doesn't climb as much or as fast.

I am not sure if that hybrid set up to control spikes, the latest version of my Unleashed tune doesn't have spikes like LMS or stock tune at all, I think you just need a better tune ;)
 

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Discussion Starter · #13 ·
Yes, the 60-70 is that "flat" spot we have been talking about. You have to look carefully but you won't see the line just go flat, its not like the mph just stay there, they just don't increase over time as they would in previous rpm's and gears.

There is a weak spot, speed would climb still with a weak spot, just doesn't climb as much or as fast.
What I was saying is that the decrease in acceleration doesn't coincide with the flat spot in the RPM line. The acceleration suffers because 3rd gear is so tall, not because there is a dead spot. Also, all cars inherently decrease their acceleration as speed climbs. I don't really see anything unusual in the datalog graph.

I am not sure if that hybrid set up to control spikes, the latest version of my Unleashed tune doesn't have spikes like LMS or stock tune at all, I think you just need a better tune ;)
I don't have any tune right now, and I don't even know if the FuSpo will reap the same benefit from the mod as the SHO. I'm hoping our car benefits as much from the boost control mod as the SHO does, though, because it makes a huge difference in the SHO according to all the guys that run it. I can't say for sure if Unleashed lets boost run wild between shifts or not. That's just what I read somewhere. If there are no spikes that means they are using the throttle to control the spikes between shifts like the stock tune does. The mod just allows the throttle to stay open without causing a boost spike from the RPM drop while the turbos are still at full tilt.
 

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Discussion Starter · #14 ·
I have definitively confirmed via datalog that the torque converter is the cause of the rpm flat spot. The "torque converter speed ratio" transitions from .6-.7 up to 1 exactly where the flat spot is and there is no lull in vehicle speed. The engine is still making full power, but the torque converter makes the middle of 3rd gear a pseudo shift point, effectively increasing the gear ratio without shifting gears.
 

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I have definitively confirmed via datalog that the torque converter is the cause of the rpm flat spot. The "torque converter speed ratio" transitions from .6-.7 up to 1 exactly where the flat spot is and there is no lull in vehicle speed. The engine is still making full power, but the torque converter makes the middle of 3rd gear a pseudo shift point, effectively increasing the gear ratio without shifting gears.
very interesting. Thanks for that info. I'm guessing that this is by design? Or some sort of tradeoff?

I'm guessing a 3rd party TC would eliminate it
 

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Discussion Starter · #16 ·
very interesting. Thanks for that info. I'm guessing that this is by design? Or some sort of tradeoff?

I'm guessing a 3rd party TC would eliminate it
There's really no reason to eliminate it tho. Its increasing the effective gear ratio right in the sweet spot of the torque band. Its like a mini CVT in the middle of 3rd gear. Increasing the drive ratio when the engine is in its sweetspot is what makes CVTs so fast. The only problem is that they don't sound right. That's whats driving everyone mad here, too. Even though its not hurting performance, it sounds funny.
 

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I have definitively confirmed via datalog that the torque converter is the cause of the rpm flat spot. The "torque converter speed ratio" transitions from .6-.7 up to 1 exactly where the flat spot is and there is no lull in vehicle speed. The engine is still making full power, but the torque converter makes the middle of 3rd gear a pseudo shift point, effectively increasing the gear ratio without shifting gears.
So essentially torque converter is locking up right?
 

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The "torque converter speed ratio" transitions from .6-.7 up to 1 exactly where the flat spot is and there is no lull in vehicle speed.
That explanation works for me. That's exactly what it feels like. At least on my butt dyno.
 

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Discussion Starter · #19 ·
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