thumbs up !

Just need to drive with a light foot and get used to it.
my 2 cents.

 

Right...... I have been doing some more driving yesterday and today and think I am getting to grips with what my issue is.

As already stated, when I'm driving the car 'hard' I love it! The response is excellent.

What has been an issue for me is the 'over-sensitive' nature when simply cruising along in traffic etc. Today, I noticed my issue isn't when I lightly apply the accelerator for a split second. It's when I apply a little more pressure for maybe a few seconds - with the intention of increasing speed by just a little. What actually happens is that the amazing response kicks in, and it's the turbo 'kicking in' momentarily just prior to me lifting off that is causing the thing to feel so jerky.

I think this is probably only an issue with a diesel that is fitted with a manual gearbox (as the manual SB is more aggressive). The engine output on my car is also upped so this maybe compounding the situation further. So, I'm interested to hear from any manual 3.0 diesel drivers with a SB fitted.

I am getting used to it more, but there are situations where the car will jerk - it's simply that sensitive, no matter how light I am with the right foot.

Got to love the response gain in other situations though. Also, on the plus side, I don't have to change down a gear now as often, where I maybe would have had to before - it will pull in 3rd where 2nd would have been needed.

 

HI Palmo,

As XBMWX stated already, I also have the SB fitted since a week on my 325D manual.

I totally agree to your comments. Here is my 2cents worth:

1. Autobahn and open road: Love it, although it makes controlled drifts VERY hard! I constantly "overpush" the pedal - logical as it multiplies everything by 1.3, but when I would lets say want the pedal in slightly above idle, ie 3-4 percent power, there just isnt such a thing. Mathematically just impossible, and thats exactly what you feel. Thats also what you need in low moving traffic or cueing in front of traffic lights etc. Now, if you are on a road, going steady, and there is a situation where you need immediate power - well, you get it!!!

2. City traffic. Mhh, could live without the SB. I live in vienna, and I have to travel the busy roads every day, and it is a b..tch to drive!! I feel like I am a beginner again, constantly slipping clutch, over-reving etc. Without sounding to girlish i hope, it also depends on you footwear. Sneakers - controllable - heavy boots or similar, well, lets just say it is more work than before.

3. Something you havent reported: When i do high speed driving on the Autobahn, and I do that often, and I go 100 percent power, and then traffic ahead moves into my lane, i usually ease of the power instantly, i.e de-press the throttle instantly. What I noticed is when my foot is approx (hard to say as I cannot see it) 3/4 of the distance, the car "lurks" forward a little bit, as if the 100% power is acuatlly at 75% throttle, NOT at 100%. so from low to high, here is what it feels like

Throttle Delivery
5 10%
7 20%
10 35%
20 50%
30 60%
40 70%
50 80%
60 90%
70 100%
80 95%
90 95%
100 95%

Now, it should be like that I understand, but it should also be at 100% power the rest of the pedal way after 3/4 of the distance, NOT feel like a throttle decrease. However, the TOP speed appears unaffected by that - weird....

4. What I noticed though is that I adapted my driving style to the car:

AUDI S4 - Biturbo, had to check the revs to make sure I have instant power, or maybe downshift. Never an issue.
BMW M Roadster: Well there was power in ANY gear, no adaptation necessary.
BMW e46 320D - just made sure that the revs are above 2500 - then there was no turbo lag and decent throttle response

My current 325D: I still try to stay above 2500 RPM when I want to make sure I get immediate response. I was hoping for the SB to cure the turbo lag which is still aparent in the 3.0 Liter diesel (despite what they say "400NM above 1250RPM), but it didnt (well and it shouldnt either).

SO my vedict - I will use it for a while, then take it out to see what the difference is, then make my final decision.

Rgds

Thyrus

 

Thyrus - Some excellent observations there - very similar to my experiences. At last - someone else with the same issues as me - I'm not going mad after all.

Your 3rd point, regarding the 100% throttle thing. I have indeed noticed this. However, I have a slightly different perception of what maybe happening here. As you say full throttle is now applied at approx. 70% of the pedal travel. Applying the last 30% of pedal travel in theory does nothing. However, when driving hard it is inevitable that we will press beyond the 70% position, and in fact to the floor (100% pedal travel position). When we go to lift off, what I think happens is that the power remains on for a slit second longer that our brains say it should, as releasing the first 30% does nothing. Therefore, when the power is reduced, it is a split second late. Also to compound this, I can only presume that the power is reduced very quickly (based on the assumption power is decreased as responsively as it is applied). Therefore the result is the jerk. I have found ways of driving around this by lifting about 30% of the pedal travel early......seems to work. However, this obviously doesn't cater for those situations where you have to lift abruptly for whatever reason.

I fully agree with your comments about the turbo lag - this is a part of all turbo'd engines. I think it is this lag which causes the car to feel 'jerky' when applying a light amount of power with the SB, as stated in one of my posts above. A little bit of throttle (very light) seems to be fine, a little more.......still fine, then just as you wish to ease off the turbo cuts in abruptly.

What are your thoughts about trying an 'auto' version of the SB that is supposed to be 'less aggressive'?

I agree with your verdict, that "I will use it for a while, then take it out to see what the difference is, then make my final decision".

 

Love my SB to bits... . Try the 25s trick, maybe you won't need SB at all. Many have tried with success.

 

Tried it before, didn't notice any difference. Think this may only be for auto's anyway - as I say tried it and didn't notice any difference, although this was prior to SB fitment..

 

Give it another shot with the SB, maybe just maybe you'll get lucky this time round. Anyway its a simple, free and quick procedure.

 

Its not for auto's only, I have a 6 speed stick shift and the difference is amazing the car speeds up so much quicker.

 

HI again,

Swapping it for an AUTO - mhh, XBMWX suggested already we swap ours (my manual and his auto), so next time this is something we will do.

However, without having driven it - currently I would not feel right about getting a "downgraded" SB - for me, I would have to say it it either the real thing (i.e manual) or nothing.
But I will see when Pete and I did the swap.

Rgds
Patrick

 

I have the same dilemma as you in NOT wanting a 'downgraded' SB. I guess I want the best of both worlds - i.e. massive response when required, but with the ability to reduce the sensitivity.

Anyway.....after driving my car further (another 500 miles) I would say that I am beginning to get used to it. But I also feel I have found something else that has 'improved' the situation. As suggested by a few people in this thread and after re-reading the thread 'The "hold down accelerator for 25s" trick for smoother shift' it is suggested that this will work on a manual car. Indeed I have tried this before with no real benefits. However, over the weekend I tried this with the SB fitted, and I must say that I think it has improved the driving of the car. Response is still excellent, but a lot of the jerkiness seems to have gone. Can't be 100% sure that I'm not imaging it, but I'm quite sure I'm not! So, this will maybe help you Thyrus - it's worth a try. At the moment I am really beginning to enjoy driving with the SB fitted.

Will update again after further mileage has been covered with a conclusion.