CEB

Which is the same as "stepping on the gas" harder.

I knew there was a white paper around here somewhere. Here it is.

ttoE550

I suspect that there is a lot of truth to this, and the "throttle lag" I am experiencing simply comes from sometimes being on a gentle curve and sometimes being on an aggressive curve. This is my first ever drive-by-wire car, so I am used to having the car respond the same (adjusting for obvious variables) each and every time I give, say, 70% gas.

I still see this as a safety issue. My eyes, training, and years of driving experience tell me how much throttle to give -- and the car is somewhat randomly changing my input without my permission or knowledge. If I am pulling out into traffic while simultaneously turning, I don't want a slow sluggish response until I get to the 90% threshold and then bang! It makes no sense to me.

carver

Thanks for the link to the white paper. I find it interesting, but the test car used has almost no lag to start with. Given this, I wouldn't consider it to be much of a test of how (or if) the sprint booster would work on a car with considerable lag. (I do have a hard time believing it would make a difference, but I'm not beyond giving it a try.)

I haven't driven an SLK230 (R170), but I have an SLK350 (R171), and it has what I consider to be no noticeable lag - far different from my E550 in the condition I noted in the original post. My SLK feels as if the message to accellerate goes from my brian to the engine before my foot can react. Of course, it is a very different car from the E.

In general driving, I'm quite happy with the response of the E550. It is just that annoying and long lag after very briefly coming to a stop that bothers me.

captj3

This was a good read. It's amazing how simple the sprint booster is. I don't find there is any lag per se with my 550. I have been driving cars with drive by wire for years and understand what people are talking about. I find the pedal feel is very different form my other cars. It is very stiff compared to others. The more I drive the E the more I get use to it's feel and adjust to it. A soft pressure on the pedal feels like lag , but isn't. So far I am very happy with the E550 for the last 2 1/2 weeks and 1200 miles.

BenzE350

Why do you say there is problem above - and no problem below?

Flip / Flop

K-A

My top comment was about the delay when going from R to D, when in a tight (oh sh**) situation.

As far as throttle lag, i.e when in "D", and accelerating off of a stop, I don't feel any problems, and feel that it's by design more-so.

BenzE350

Thanks for the link with the white paper!

I think this explains the delay during a 3-point turn. Because of the implementation as summarized below, the throttle sensitivity is changed during reverse, and there is a definite delay as the sensitivity goes from reverse to drive.

In electronic throttle control systems, the accelerator pedal is connected to a sensor that sends a signal to the ECU. The ECU is connected to a servomotor that operates the throttle. In most cases, the ECU operates the throttle in proportion to the input from the accelerator pedal. However, in some cases, it does not. For example, in some Mercedes vehicles, Mercedes reduces the pedal sensitivity when driving in reverse, as explained in their service manual:

“The pedal value sensor characteristic curve is changed if reverse travel is recognized by the control unit. The throttle valve opens more slowly. The entire opening angle in this case is approx. 50%.”

BenzE350

So you agree there is a design issue in regards to the throttle response as evidenced by your "oh sh**" comment when going from R to D.

Tjdehya

Shifting from R to D is not a throttle response issue it’s a slow transmission issue... two completely different problems.
I think we all know about the slow transmission but I have never experienced the "throttle response" problem mentioned here.

bambu1

Had the same stop-then-go brake hesitation with my 2007 CLK350. Most noticeable when the car is cold....took it to the dealer and the Service Assistant said it happens because the transmission goes directly to second gear when the car start (not first gear as one might expect). I have no idea what the tranny gear has to do with the brakes...anyway, the technicians kept the car for a day...

They did mitigate the problem with a "software upgrade"; here is what the technician typed on the invoice:

"Perform short test no codes found on ME or Trans check vehicle for updates found ME and Trans updates. Perform new ME control unit software programming. Control unit was completed successfully. The SCN coding sequence has been completed successfully. Also perform ETC control unit programming. Control unit programming was completed successfully. The SCN coding sequence has been completed successfully. Final short test ok no codes."

When I got the car back from the dealer, the hesitation seems to be gone, or at least I'm just not noticing it.

Hope this helps...good luck.

BenzE350

Not according to the white paper I read.

K-A

These are two separate issues. Transmission VS throttle response.

I have NO throttle delay whatsoever when moving off of D, just smooth takeoff. I have driven cars that literally have a seemingly 1 second jerky delay before takeoff (535i, and occasionally my old '06 E350), and it's not a pretty ride (search "BMW Throttle Tip In"). I'd suggest anyone with an E-Class who has that problem to get it checked out, because the two I've had never posed such a problem.

Now, R to D in a quick maneuver is a different story, and there's a definite delay there, not related to pedal response.

BenzE350

The R to D issue is related to the throttle response. Read the white paper.

K-A

Then I guess the throttle response is only prevalent when changing gears.

I have 0 lag when normally accelerating. I don't expect a jolty and sudden takeoff, but it feels like it works by design, no lag, but it's a smoother, softer (more luxuriously oriented) takeoff.