ECU tune + sprint booster

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It has two components to my knowledge.
1) Processing latency - this you can do nothing about.
2) Programmed damping of the throttle to smooth out erratic input from a driver. This can be varied & "improved" by a savvy ECU tuner.
Turbo lag is governed by "spin up" time & is usually countered by fitting a smaller turbo with a shorter spooling time. BMW fit a small & large turbo to give you the benefits of both.
Last edited by Glyn M Ruck; Sep 12, 2011 at 04:14 PM.
can i ask where you got your 350 tuned and with what tune and how much?
It has two components to my knowledge.
1) Processing latency - this you can do nothing about.
2) Programmed damping of the throttle to smooth out erratic input from a driver. This can be varied & "improved" by a savvy ECU tuner.
....
SprintBooster.pdf
This was clearly shown in Fig 2, where the pedal was rapidly floored, and pedal and TB response were measured. The initial throttle lag was 1/22 nd of a second, and the final lag at WOT was 1/28 th of a second. These are tiny numbers, representing the "ecu lag".
If the current TB response curve is similar to this 1998 model, the "ecu lag" is negligible.
sprint booster is just better throttle response.
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Unless the
Last edited by kevink2; Mar 30, 2012 at 12:56 PM.

However we humans are sensitive to the disconnected feel this gives us, just as we are very sensitive to audio latency.
We should remember that this is not the only lag in the system.
-We have ECU/throttle plate lag.
-We have TCU lag.
-We have lag created as the MAF fights to get fuel trim under control when we stomp on the throttle.
-We have lag created by the variable length inlet & swirl systems on the inlet manifold.
-We have flywheel/TC effects.
People are equally aware of & able to sense the SB effect. While ECU tunes are certainly able to move torque & horsepower curves around by usually giving up in one area & gaining in another I have little doubt that many tuners also do a SB type simulation & make the throttle a little more sensitive. Good for the butt dyno.
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Last edited by kevink2; Apr 1, 2012 at 12:42 PM.
However we humans are sensitive to the disconnected feel this gives us, just as we are very sensitive to audio latency.
We should remember that this is not the only lag in the system.
1) -We have ECU/throttle plate lag.
2) -We have TCU lag.
3) -We have lag created as the MAF fights to get fuel trim under control
- - - - when we stomp on the throttle.
4)- We have lag created by the variable length inlet & swirl systems on the
- - - - inlet manifold.
5)- We have flywheel/TC effects.
....
1) ECU/TP ... agreed, tiny. Back to the white paper Fig-2 , stock (1999) system. Time to rapidly floor it was .284 sec, while initial lag was .045 sec. The lag was 1/6 th the time to floor the pedal, in this test.
2) TCU ... no efffect at launch, but clearly noticeable during transient based shifts.
3) MAF reacting to stomped pedal ... Not likely, IMHO. For a quick, significant change in load, the ecu utilizes fixed open loop map sets for fuel flow vs load & rpm, and no trim (closed loop) is involved.
4) Manifold flow systems ... Don't know about this.
5) Flywheel and TC effects ... Assume you mean the rotational inertia. This is only signficant during max engine acceleration in first few gears, and even there not noticed as a lag, as it is lumped in with the task of accelerating the mass of the car.
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What I think all of this displays is how sensitive we are to latency or what we experience as lag as a Benz goes about it's business.
Last edited by Glyn M Ruck; Apr 1, 2012 at 03:39 PM.
If the current models have the same response curve, then you get this response in the TB for the listed pedal depressions:
Pedal ----- TB
1/4 ----- 4.0%
3/8 ----- 11%
1/2 ----- 29%
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Last edited by kevink2; Apr 2, 2012 at 09:56 PM.



