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2010 FORESTER 2.5XT LTD
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97 Posts
Discussion Starter #1
Hey all,

So I have roughly 3,000kms on my new FOZ XT Turbo. Question. Is it just me or does it seem like if you take it easy on the accelerator and don't push it hard that it affects the "umph" or torque of the Turbo?

It feels like my turbo has more power when I drive it a little harder consistently?

Or maybe I'm going crazy.

A friend of mine told me I should be driving this car like I stole it since the engine will perform better over time if I do.

I throw this one to the experts on here.

Thanks in advance.

D.
 

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2010 Forester XT
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75 Posts
If you drive it more aggressively, you aren't giving the turbo time to spool down as much, so it will hammer on the boost faster.
 

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2010 FORESTER 2.5XT LTD
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97 Posts
Discussion Starter #7
Thanks.

I'm also noticing that if I'm starting from a full stop (Let's say at a red light) and then begin to accelerate moderately and smoothly, NOT hammering down on the gas pedal, that I get better torque.... you know, that feeling all us turbo owners have now come to love. If I hammer down on the gas I do notice I red line the car but I don't get the same power??

I gotta be nuts. Right??


Thanks,

D.
 

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none none
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8,844 Posts
Thanks.

I'm also noticing that if I'm starting from a full stop (Let's say at a red light) and then begin to accelerate moderately and smoothly, NOT hammering down on the gas pedal, that I get better torque.... you know, that feeling all us turbo owners have now come to love. If I hammer down on the gas I do notice I red line the car but I don't get the same power??

I gotta be nuts. Right??


Thanks,

D.
Nope, many have noticed that especially on a stock FXT.
 

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2016 Outback and WRX CVT
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2,551 Posts
ECU is learning how you drive. Reset it, drive it hard for a day or so. Should be good to go!

I think.
^ Not really - the ECU doesn't really "learn" in that manner. :wink:

What the ECU "learns against" is knock - it'll do everything in its power to prevent knock: i.e. to save its own life.

And once the ECU detects knock, various algorithms are used not only in terms of preventing further knock, but also to return the car to a state where it is the strongest possible - thus, "learning." It "senses" where there is knock, it "remembers" the event, and it re-probes that problematic area and make subsequent adjustments to either further minimize perceived knock, or to let the car incrementally improve "performance" again, given that no knock is perceived, upon revisiting that area.

There's really no other "learning" involved.

An ECU "reset" sometimes makes the car feel like it's "faster" or "more lively" as, in a vehicle with something wrong - i.e. that the ECU had determined, previously, there was knock, and was thus running, to some degree or another, fail-safe parameters - a "reset" effectively blanks the ECU of such previously learned "danger spots," so the car runs up to and through such zones; and while it will re-learn those problems, that doesn't happen instantaneously, which is then why many people suggest to "reset" your ECU on a regular basis, because they're essentially masking such issues.

On a perfectly performing Subaru, your dynamic timing advance modifier actually defaults to a lesser value when you've performed a "reset," and if anything, such a "reset" will actually make your car slower, as it will not be afforded full timing advance under a WOT run, immediately after blanking the ECU. However, at the same time, provided that the vehicle is perfect, your IAM will also rapidly climb after such a "reset," even without "cheats" such as the "Vishnu Reset," and you'll very quickly see the car pulling just as strongly as it can.

:smile:


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Hey all,

So I have roughly 3,000kms on my new FOZ XT Turbo. Question. Is it just me or does it seem like if you take it easy on the accelerator and don't push it hard that it affects the "umph" or torque of the Turbo?

It feels like my turbo has more power when I drive it a little harder consistently?

Or maybe I'm going crazy.

A friend of mine told me I should be driving this car like I stole it since the engine will perform better over time if I do.

I throw this one to the experts on here.

Thanks in advance.

D.
Like the others here have said, it's all about keeping your turbo "on-boil."

If you have a boost-gauge, you can watch it to learn how turbo boost responds to your various throttle inputs, which should help you better understand why you're feeling/seeing what you are.

Similarly, having the automatic in "Sport" mode - or if you're just really aggressively driving - will allow you to hold lower gears longer, which will typically also help minimize lag and to keep the vehicle in the meat of its powerband.

And as for the standing start?

If you're going to go WOT right from the get-go, it's more or less useless to just romp on the accelerator. Instead, brake-torque and launch.

You'll not want to do this too often, though. It's not good for the tranny.
 

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2001 Forester
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1,140 Posts
Thanks.

I'm also noticing that if I'm starting from a full stop (Let's say at a red light) and then begin to accelerate moderately and smoothly, NOT hammering down on the gas pedal, that I get better torque.... you know, that feeling all us turbo owners have now come to love. If I hammer down on the gas I do notice I red line the car but I don't get the same power??

I gotta be nuts. Right??


Thanks,

D.

Boost and torque taper towards redline. So your butt dyno is correct, when it nears redline its not pulling as hard as when its in the peaks of your torque curve.
 

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2016 Outback and WRX CVT
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2,551 Posts
^ That's very true as well.

With the small factory turbo, it simply "runs out of breath" up-top.


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Just get on the gas and scream "POWER" like the presenters on Top Gear. :biggrin:
^ :woohoo:
 

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2010 FORESTER 2.5XT LTD
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97 Posts
Discussion Starter #13
Wow.

You guys are really smart!

Great info.

If the recommendation is to reset the "ECU" often my question is "Is it harmful to the vehicle to reset the ECU this many times?" and "Is this something that I can do or a procedure that should be done by the dealer?"


Thanks,

D.
 

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2016 Outback and WRX CVT
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2,551 Posts
^ If your car's "healthy," there really should be no reason to "reset" the ECU - ever.

It's continually learning and adapting, to maximize power while keeping itself safe (i.e. warding off knock) - and the more data-points it has to learn from, i.e. it's "memory," the better.

Given that the random "skunked" tank of gas or, say, a dirty air-filter or other intermittent mechanical issues (i.e. spark plug, etc.) - or if your area switches from summer-formulation to winter-formulation gasoline - may cause the car to hickup a little from time-to-time, a "reset" may be the kneejerk reaction, but truthfully, once the car's "healthy" again, it should rather rapidly learn to overcome those rough spots again, returning itself to full power.

Is it "dangerous," per se?

One knock can kill an engine - but it's also true that in the vast majority of cases, it doesn't: that's why the ECU responds so aggressively to try to avoid knock, yet, it's still mainly a "response" thing, not nearly as much "predictive" (although, for example, if you idle the car for a length of time at, say, a traffic light, an increase in underhood temps - one that's in-turn sufficient to raise the intake air temperature above threshold - will signal the ECU to pull timing at-takeoff, to prevent potential knock: so, yes, in this case, it's "predictive," but it's a rather simplistic algorithm compared against the reactionary route). In this manner, "resetting" the ECU to try to get the car to "go faster" again theoretically allows the car to run up to - and maybe even through - those previously determined "rough spots/danger-zones" that the ECU had earmarked, while bypassing that same "learned" safety (i.e. that the ECU pulls a few degrees of timing at that pre-determined spot).

What I'm trying to say is that while I don't necessarily think that it's "harmful," the "reset" is, nevertheless, a bypass of the ECU's best attempts to preserve the vehicle, and as-such, can pose a risk if, for example, you do have something truly mechanically wrong with the vehicle (or a mis-matched tune), and that is the same no matter who does the "reset" procedure.

But truthfully, the real (and only) danger in it would be if someone were to repeatedly reset and reset again, thinking that this is somehow magically allowing their vehicle to return to a state where they're "making best power," while being blissfully ignorant of the fact that there's something truly wrong.

I hope that makes sense! :smile:
 

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Discussion Starter #15
^ If your car's "healthy," there really should be no reason to "reset" the ECU - ever.

It's continually learning and adapting, to maximize power while keeping itself safe (i.e. warding off knock) - and the more data-points it has to learn from, i.e. it's "memory," the better.

Given that the random "skunked" tank of gas or, say, a dirty air-filter or other intermittent mechanical issues (i.e. spark plug, etc.) - or if your area switches from summer-formulation to winter-formulation gasoline - may cause the car to hickup a little from time-to-time, a "reset" may be the kneejerk reaction, but truthfully, once the car's "healthy" again, it should rather rapidly learn to overcome those rough spots again, returning itself to full power.

Is it "dangerous," per se?

One knock can kill an engine - but it's also true that in the vast majority of cases, it doesn't: that's why the ECU responds so aggressively to try to avoid knock, yet, it's still mainly a "response" thing, not nearly as much "predictive" (although, for example, if you idle the car for a length of time at, say, a traffic light, an increase in underhood temps - one that's in-turn sufficient to raise the intake air temperature above threshold - will signal the ECU to pull timing at-takeoff, to prevent potential knock: so, yes, in this case, it's "predictive," but it's a rather simplistic algorithm compared against the reactionary route). In this manner, "resetting" the ECU to try to get the car to "go faster" again theoretically allows the car to run up to - and maybe even through - those previously determined "rough spots/danger-zones" that the ECU had earmarked, while bypassing that same "learned" safety (i.e. that the ECU pulls a few degrees of timing at that pre-determined spot).

What I'm trying to say is that while I don't necessarily think that it's "harmful," the "reset" is, nevertheless, a bypass of the ECU's best attempts to preserve the vehicle, and as-such, can pose a risk if, for example, you do have something truly mechanically wrong with the vehicle (or a mis-matched tune), and that is the same no matter who does the "reset" procedure.

But truthfully, the real (and only) danger in it would be if someone were to repeatedly reset and reset again, thinking that this is somehow magically allowing their vehicle to return to a state where they're "making best power," while being blissfully ignorant of the fact that there's something truly wrong.

I hope that makes sense! :smile:
Yes, this makes a LOT of sense and I thank you for the explanation.

D.
 

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2016 Outback and WRX CVT
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^ Again, no problem - glad to help. :smile:

Oh, and one small caveat:

Above, I said "the more data points, the better."

Well, the car only has a finite "memory." It can only remember - i.e. learn - so much.

The datalogging/tuning tools, such as RomRaider and Learning View, to say the least of the Forums which hosts their technical discussions, can offer you a lot of insights as to how the car works: how it "thinks," if you will.

I'm just an amateur at that stuff, and still learning, myself, so I am ill-equipped to offer you any advice aside from one simple one..... :smile: Download those programs, get yourself a suitable Tactrix cable, and read-up on the basic tuning/datalogging threads on NASIOC and the RomRaider Forums.

For me, my personal goal is not to tune.

But rather, to simply know enough to know when there might be something wrong, so that I can properly seek help. :smile:
 
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