jherm

So after a miserable installation process, I finally got my sprint booster installed. My problem was that I never really found a decent cavity beneath the carpet to place the SB, but finally got it jammed in there enough to be able to get the pedal assembly back on. I couldn't find a good empty space for it and was hesitant to push it back there with too much force as I really didn't want to mess up the wiring somehow and seriously screw something up. Finally, I was just so frustrated and ready to done with it that I said f**k it and just jammed it back there.

Anyway, went for a quick 5 minute drive after. I was under the impression that it helped with the initial lag between when you hit the accelerator and when you take off. The delay seems to be the same with the sprint booster. The big difference is that it holds the gears longer. Specifically the first driving gear from a stop (which I think is actually 2nd gear). I didn't have a chance to really test it out too much. I assume it only holds gears and keeps the aggressive shifting style when you are hammering the pedal. And that it will still allow a smooth ride when you are just cruising or have others in the car.

Are all of these observations consistent with what you all have experienced?

superlubricity

Everything you need to know -> https://5series.net/forums/index.php?showtopic=80784

C's Bimmer

Something is not right with your install then. Also, no need to jam the box back there. Just put it on the side of the pedal, after you reinstall the pedal.

jherm

Good god, that is not what I want to hear. Installation took 2.5 hours in 103 degree heat. And I was barely able to get pedal assembly back on. And I don't know how you would be able to "put it on the side of the pedal". The assembly doesn't seem to come close to sliding back into place with the SB plug anywhere on the exterior of the carpet. I'm gonna need to see a detailed picture of that setup to believe that's possible.

sdg1871

Your impressions do not sound right (as least for a functioning S. It does help with the lag but does not eliminate it. But once power comes on, it comes on a lot stronger with SB than without. My SB has no impact on my Steptronic's ability to hold gears which is correct because SB merely amplifies the throttle signal and is not hooked up to the transmission.

terente0081

@sdq1871 - it does keep the gears longer by giving more throttle. The steptronic doesn't have fixed points to shift gears, it decides when to shift depending on the way you press the accelerator. If SB gives more throttle, it will also keep the gears longer.
The lag is still there, but reduced. My SB fits between the accelerator pedal and the carpet, on the right side of the pedal. It's mostly under the accelerator, you can't see it's there unless I point you where to look.

jherm

That is a great explanation. It seems to hold gears in close relation to how hard i hammer the accelerator. If I go all out, it will hold until redline. If I go 75%, it will hold until a bit less, etc.

And I think I was expecting the SB to completely eliminate the lag (which it does not). So when I got past that, I think it is reducing lag a bit. But it seems to be so a pretty small reduction that is nearly imperceptible. I'm pretty sure my SB is functioning properly. I just didn't know exactly what to expect.

v_therussian

I'm just glad you've finally got it done

On a serious note, you're not the first Auto trans. driver to not be overwhelmed with the awesomeness of the SB on the first drive...

jherm

I know. I really appreciate you letting me talk through some things with you during the install. Apparently, I just needed a little frustration to let me work up the nerve to say screw it and just get it under the carpet by any (or nearly) any means. I was worried about damaging the original wire somehow when I was trying to push the sprintbooster back up into the carpet. But I think you would really have to cut it to damage.

terente0081

I don't know about manual transmission, but I loved my SB on Auto since day 1. Before the SB I had to press the gas pedal really hard to get the car to downshift and it didn't even downshift all the time so I had to do double gas presses to force it into downshifting. With the SB all I need to do is pinch the accelerator and the car downshifts and surges forward. That's in D mode. In DS is very sensitive and aggressive and in M mode is brutal.
SB on Automatic transmission makes passing a breeze.