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BMW = Fahrvergnügen
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Discussion Starter · #1 ·
I've been reading through my european car and Bimmer magazines again and noticed those Sprint Booster ads in there. Now, I remember smolck mentioning this thing recently too, which is why I decided to look further.

It claims to remove the drive-by-wire induced throttle lag and increase throttle response simply by inserting a little doodad between the accelerator pedal connector and the wire loom that goes to the ECU.

So, naturally, I'm thinking that this cute little thing could be anything...who knows what the heck it does, especially since the lag doesn't have anything to do with the wiring in the pedal. It's all got to do with the electronic committee between you and the engine deciding, after much deliberation, how to spin the engine up when you press the loud pedal. The committee's still there, so how does this thing work?

ECU remaps like Shark Injectors and the like simply streamline the committee's decision making process and change their priorities from saving more money to making more ponies faster. That I understand. But how does the thing work without changing anything else?

Well, there's a guy with more time on his hands than me who figured it out.

http://www.peony888.com/VS/SprintBooster.pdf

Read it for the in depth stuff, but the short of it is that the Sprint Booster is a little amplifier, nothing more. It increases the signal from the pedal box by about 30%, meaning that the ECU thinks you're pressing the pedal about 30% harder than you really are. You're effectively using a megaphone to make your will known to the committee.

This would definitely make the throttle feel more responsive since you're making a smaller amount of right hoof count for more, but know this:

For 300 bones, you get:
  • A pedal that feels more responsive because the gain has been turned up,
  • A pedal where the top third of the range of motion doesn't do anything since you've multiplied the signal by 30% and max it out by 2/3 throttle,
  • And, the kicker, the same thing you would have gotten if you pressed the pedal a bit harder.

Knowing this, I don't think it's a worthwhile investment. It doesn't really get you anything unless you really want a more sensitive pedal.

It isn't like a Turbonator in that it actually does something, but I still think it's a waste.

Regardless, my point here is to educate such that y'all have complete information and can thus make informed decisions.
 

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.oo=||=oo.
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...And, the kicker, the same thing you would have gotten if you pressed the pedal a bit harder....
That's where the problem lies. One can reason that one just needs to press the pedal further, but throttle response has a big effect on the feel and impression of a car's responsiveness, IMO.

I've recently purchased a SprintBooster for an E90. Great product. A little too pricey. My 2 criticims: 1) it would also be nice to have a switch to toggle between boosted throttle response and "normal" and 2) the dongle shape makes it difficult to stow away neatly.
 

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BMW = Fahrvergnügen
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Discussion Starter · #4 ·
That's where the problem lies. One can reason that one just needs to press the pedal further, but throttle response has a big effect on the feel and impression of a car's responsiveness, IMO.
Man makes a good point. It really is a matter of personal taste. I for one am for some reason mildly insulted by the concept of a throttle where 1/3 of it doesn't do anything. It's an engineering thing...a control that has a section, even a small one, that has no effect annoys me. Let's not even get into the problem of nonlinearity in controls...nonlinear throttle included. 50% pedal input does not equal 50% engine output? ARGH!

But I digress...:p
 

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Is it Trackday yet?
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It's not that 1/3 of the throttle doesn't do anything all the time. It's when you mash the pedal too fast that it doesn't do what you want it to. Mashing it fast to the floor results in a short delay in reaction from the computer which translates into a delay in acceleration. Do it slower, yet briskly, and you'll have better results.

The problem? It's difficult to re-train yourself to do this. After 4+ years with this car, it still bugs me. The throttle, especially from 0-1/3 throttle doesn't like abrupt changes.

For $300 bones, go for the Shark Injector and get the same + other tuning as well.
 

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Keeping it surreal
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This is basically the old whore`s trick that GM used for years....crank up the throttle tip-in to *give the impression* that the car is a lot faster than it really is....in reality, all it *really* does is make the car twitchy during parking maneuvers....
 

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Man makes a good point. It really is a matter of personal taste. I for one am for some reason mildly insulted by the concept of a throttle where 1/3 of it doesn't do anything. It's an engineering thing...a control that has a section, even a small one, that has no effect annoys me. Let's not even get into the problem of nonlinearity in controls...nonlinear throttle included. 50% pedal input does not equal 50% engine output? ARGH!

But I digress...:p
It's done to prevented go over 4.5 V and burn your ECU or components on this ECU. At least they have thought about it. It's probably possible go over 4.5 V but need a money for more studying, that is in most cases like this companies doesn't one.
 

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I do'nt make mistakes.
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This is basically the old whore`s trick that GM used for years....crank up the throttle tip-in to *give the impression* that the car is a lot faster than it really is....in reality, all it *really* does is make the car twitchy during parking maneuvers....
+1. My Dodge Dakota feels like it has 500hp based on tip-in. Its very difficult to take off smoothly, and so my inital accleration ends up granny like because the alternative is to chirp the rear tires, or spin the tires if its raining.

Personally, I never feel the need for large, aburpt throttle changes. Driving for me is all about being smooth.
 

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That's where the problem lies. One can reason that one just needs to press the pedal further, but throttle response has a big effect on the feel and impression of a car's responsiveness, IMO.

I've recently purchased a SprintBooster for an E90. Great product. A little too pricey. My 2 criticims: 1) it would also be nice to have a switch to toggle between boosted throttle response and "normal" and 2) the dongle shape makes it difficult to stow away neatly.
Well, just a note from a recent trip, 3 hours ago, from the BMW dealer with the acceleration delay issue. S/A agrees there is a lag, of course. What to do about it.....basically nothing since there is no apparant fix. So, on the test drive after acknowledging the problem, I ask, "what if I added an after market Sprint Booster?" Respons was, it might invalidate your warranty and then again, it might not. So, to fix the problem and not look like a total "Dork" who can't drive an expensive vehicle. Hmmm, another question in life.
 

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Ubergeek
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FYI, this is the same thing that the "sport" button does on the E46 M3 (on other BMWs like the E39 M5, it does other things like reducing power steering boost.. but on the E46 M3, all it does is remap the throttle position).
 

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The Dude abides.
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For whatever it's worth to you guys, and I'm sure it ain't much, I have one in my 325XI. You can get a less aggressive, standard or a more aggressive mapping boost. The aggressive is really just uncivilized IMO. I went w/ the standard and really like it a lot. Probably wouldn't spend the money on the less aggressive setting. Bob kind of has a point about the car becoming a bit twitchy, but not for parking maneuvers, I find the twitchieness when driving around the city. The new stiff suspension coupled with the crap road surfaces here and your foot inadvertently pressures the pedal in an annoying feedback loop. As far as parking, that's what the clutch is for. I'll say this, don't get it if you have an automatic, just step on the pedal. If you have a stick and do occasionally do some sport driving w/ heel-toe down shifting this little gadget will make the car feel significantly sportier. If your version is just driving fast on the interstate don't bother, I see its real value in moving up and down between gears quickly. One place I noticed it most was downshifting from 3rd to 2nd. The gear ratio between the two gears in the 5 speed feels noticeably larger compared to all the other gears. Going into 2nd I used to have to mash the throttle to blip the revs up to match RPMs. Now it's a blip up and much less of a issue. Another thing to keep in mind is the thing just goes in and out from behind the pedal easily. Try them all and find one you like, and when you part ways w/ the car take it out and sell it on ebay or whatever - it's not permanent. Finally, the mapping is not a simple linear boost of the original mapping it's different and more aggressive, and as far as the last 1/3rd, think about it, how often do you really have the pedal actually mashed to the floor? Can't wait for feedback on that last comment. Anyway, just one man's opinion.
 

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FYI, this is the same thing that the "sport" button does on the E46 M3 (on other BMWs like the E39 M5, it does other things like reducing power steering boost.. but on the E46 M3, all it does is remap the throttle position).
Got 750I but I guess it doesn't matter what series anymore. thanks.
 
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