znod

Hi Friends:

I think the biggest conceptual problem with the Steptronic is that one can't completely turn off the management function's horsepower robbing effects of traction control, while leaving the remainder of its stability control effects alone. I think that the issue here is that the DSC and DTC are so interdependent that one has to have both on at least to some extent or presumably neither on. So, my understanding is:

1. DSC on--both DSC and DTC functional--stability is maintained as well as possible and virtually no wheel spin is allowed;
2. DTC on--both DSC and DTC functional--stability is maintained, albiet not as well as above, because significant wheel spin is alllowed by DTC--sort of like with a LSD--to help out in slippery spots; and
3. Both DSC and DTC off--Presumably neither produces any effects.

Well, it turns out that, on my 545i, lingering effects of at least DSC are possible even when both DSC and DTC supposedly are turned off. My evidence is that after a start yielding excessive wheel spiin, then the next shift is affected significantly--i.e., the Steptronic generally shifts to 2nd gear way sooner than otherwise. Need less to say, elapsed times and terminal speeds suffer immensely. Obviously, it this effect is not a result of DSC, then I have a malfunction.

Has anyone else had this sort of experience? Is there any way to really completely shut DSC and DTC down and to rid myself totally of their horsepower robbing effects when I want?

grogan545

Is it possible that while getting excessive wheelspin you are reving to redline?This will cause the computer to shift to the next gear .Your actual speed may be much lower than the expected shift point but the computer mapping probably tracks several inputs to determine when to shift.One of these inputs is RPM's.

znod

Is it possible that while getting excessive wheelspin you are reving to redline?This will cause the computer to shift to the next gear .Your actual speed may be much lower than the expected shift point but the computer mapping probably tracks several inputs to determine when to shift.One of these inputs is RPM's.
[/quote]Hi grogan:

I see what you mean, but it is the tach I am watching. I should have been clearer above. Once the wheel spin has stopped, and I am under way, the Step shifts to 2nd at, for example, 6k RPM rather than close to 6.5k RPM. This is the reason I generally abort excessive-wheel-spin runs even though the runs might not be too bad if the Step would shift to 2nd properly.

znod

Bump. Any thoughts others?

0700700

on a 745li once both are off you can skid the car around ... i almost crashed it the
first time i tried it ! i dont think there is a esp style standby mode !

cobradav

I did not go back and re-read your in depth testing methods in your other threads so forgive me if I ask questions you have already answered. This power robbing shift point, is that in the DS or Sport automatic mode or is it in the manual mode where you start in M1? The reason I ask is that I have yet to see an instance where if starting in M1 with DSC/DTC off that I did not get a shift at redline. Now I must point out that my experience is not in the timed, controlled, sanitary conditioned events such as you have been trying to establish for your mod and performance data gathering purposes. Mine is just during clear, straight road efforts under what I term safe situations (no traffic visible, no weather impairment, at least 2 mile straight ? (actually have a 5-mile stretch) and no law enforcement near by. I cannot get a shift to occur prior to redline in my setup.

znod

I did not go back and re-read your in depth testing methods in your other threads so forgive me if I ask questions you have already answered. This power robbing shift point, is that in the DS or Sport automatic mode or is it in the manual mode where you start in M1? The reason I ask is that I have yet to see an instance where if starting in M1 with DSC/DTC off that I did not get a shift at redline. Now I must point out that my experience is not in the timed, controlled, sanitary conditioned events such as you have been trying to establish for your mod and performance data gathering purposes. Mine is just during clear, straight road efforts under what I term safe situations (no traffic visible, no weather impairment, at least 2 mile straight ? (actually have a 5-mile stretch) and no law enforcement near by. I cannot get a shift to occur prior to redline in my setup.
[/quote]
I am talking about using DS having started in M1 (i.e., automatic shifting after engaging M1)--no sport button on 545i. The farkled shift does not occur unless I have generated what the car apparently interprets as excessive wheel spin. The bad shift is readily apparent though feel and looking by watching the tach. Thanks for thinking with me.

Thanks 700700.