AvramD

<center><img src="http://est.org/S4b6throttle/throt-double-2.gif"></center><p>Hey Everyone,

Here's episode two in my DBW throttle research endeavours. I recently drove from RI to NYC with my vag-com plugged in. I was shocked to realize that at one moment when I felt like the pedal was only about half-way to the floor, the throttle indicator was pegged at what appeard to be maximum.

Further analysis of the data confirmed this; I believe it's RPM dependant, and I didn't mess with different ranges, but... at about 3000 rpm, 50% accelerator gives you 100% throttle open. I believe this was in 3rd gear.

I suspect there are many scenarios with many different "multipliers." I haven't experimented with mid-accelerator at other RPM ranges or in different gears or neutral.

This is consistant with someone's earlier suggestion that the accelerator is a "torque request control" in that at low RPMs, you need everything it's got, to get only a medium amount of torque.

It also explains two other problems;

1) why the car is so hard to rev-match - because when you think you're only giving it 30% or so, you're nearly flooring it (this is still conjecture, I need to verify clutch-down and neutral situations with various accelerator positions)

2) Why the car feels like it's still accelerating when you lift the throttle - because it is - if you are lifting from one position to another, and both are still above 50%. As long as you are past whatever accelerator position Audi has deemed warrants full throttle, lifting to a level that is still above that will still give you full throttle. Thus you think you're telling it to slow down, but it is still going all-out.

You can see this in the graph above - I'm easing from about 63% accelerator down to 45%, and the throttle is pegged the whole time.

My appologize for forgetting to collect RPM data on this run, that woudl have been useful ;-)<ul><li><a href="http://est.org/S4b6throttle/index.html#mid-double">the latest details (and a 2nd graph)</a></li></ul>

TXurS6

Occasionally I've had the following scenario happen:

While in traffic, I coast down to a stop with the clutch in. While either stopped, or at most any speed below 5 MPH, I blip the throttle and nothing happens. Engine stays at idle. After no response, I press the accelerator further and still no response. I then slowly let out the clutch and I am able to get the engine to respond as the clutch begins to engage.

???

amgs4

i was right. rev matching on this car is not as smooth as my integra type R.

AvramD

<ul><li><a href="https://forums.audiworld.com/s4b6/msgs/51284.phtml">This is exactly what I'm trying to figure out</a></li></ul>

TXurS6

Yep, that sounds like the same thing.

one_fast_roo

I've often noticed a slight acceleration when taking my foot of the gas. Happens around 45 mph.

AvramD

so this explains that exactly - does it make sense to you?

LCP

Yuck. At this rate humans will being giving up total control of driving to their cars in a decade.

one_fast_roo

I've actually noticed dramatically improved butt dyno accelaration when I ease the throttle as opposed to floor it it's almost as if the throttle itself seems to behave is if it connected to shock absorber that dampens the actual pedal inputs. The variable intake manifold may require this behavoir?

BTW I too have trouble achieving smooth shifts (15 yrs driving a stick). But I am finding that if I wear some thin soled shoes it's much easier.

AvramD

the increase in acceleration after lifting the throttle. I'm not convinced it's the DBW program yet though. I think it is just the engine getting to a speed where it's more powerful, and that happening to occur about the same time I lift the pedal.

Now that I know the throttle is staying wide open, I'm finding that explanation more believable; the times I've noticed that happening, the delay between lift and the increased power has varied. Thus I think it's just a question of what rpm I lifted at vs. where the knuckle in the power curve is.

Jury's still out though, I'll experiment with this too.

I'm not sure that it's really unpredictable either. It's not what we expect, but I have a feeling it is consistent, it's just taking us time to get used to it. I suspect we're all going to either learn to time our squeezing of the pedal in synch with the throttle's own program - that or just get used to how far we have to lift it a different RPMs, to get it to stop accelerating.

My biggest complaint is just that the incredibly small range of pedal motion that covers full throttle is difficult to physically work with.