[TX3M]

I've noticed that when I'm driving slow (like in stop and go traffic), the tranny shifts into 2nd and sometimes even 3rd right away. It should hold 1st gear longer, but it never does. It's only when I accelerate hard from a dead stop that it holds 1st longer. Really, it doesn't hold any of the gears long enough under "soft" throttle application unless I'm in sport plus. This, in my opinion, is the greatest contributor to the throttle lag.

[BobsM3Coupe]

Originally Posted by atrueb

The m40i motor is truly spectacular, but in my opinion it does have a bit of lag in comfort mode when accelerating from a dead stop.

The lag is because in Comfort mode, the vehicle starts out in 2nd gear. However when it senses full throttle from a start, it has to reprocess and select 1st gear. Thus the delay. Sport mode pretty much eliminates that delay, but there is still a slight turbo lag, which is normal for just about all turbo engines.

[Crassus]

Originally Posted by BobsM3Coupe

The lag is because in Comfort mode, the vehicle starts out in 2nd gear. However when it senses full throttle from a start, it has to reprocess and select 1st gear. Thus the delay. Sport mode pretty much eliminates that delay, but there is still a slight turbo lag, which is normal for just about all turbo engines.

Exactly. The B58 is an amazing engine but it's not perfect for enthusiastic driving. Below 3k rpm it doesn't feel leaps better than the 20i. Responsiveness is only sharp above 3-4k rpm.

This is not a problem because its an engine for mlites. If throttle responsive is a priority then an M car is the only answer.

Regarding comfort setting, it's programmed for good fuel economy and is not the right engine mode for taking full advantage of the B58.

In my M140i I tend to drive with the gearbox in Sport and engine in a Sport mode that's been configured to leave suspension and steering in sport.

[corn18]

I emailed Racechip to see if I could use their XLR pedal box that I ordered for my Z4 on my X3 M40i and they said it would fit. So, when my 40i gets delivered, I'll put the XLR on it and play around for a while.

[r33_RGSport]

Originally Posted by corn18

I emailed Racechip to see if I could use their XLR pedal box that I ordered for my Z4 on my X3 M40i and they said it would fit. So, when my 40i gets delivered, I'll put the XLR on it and play around for a while.

Yes, so far all BMW throttle by wire uses the same gas pedal mapping.
So, from E9x to G-series, the RaceChip XLR will work.

[corn18]

Well, I put the pedal box on my Z4 and it made a huge difference. I put the Racechip tuner box on by itself and I think it had more oomph. Then I added the Racechip pedal box and set it to sport+ and now I have the Z4 I always wanted. The turbo lag is still there, but just driving around it now "feels" more sporty.

I'm sure this pedal box will make anyone with a lag issue on the X3 very happy. I'm not going to put it on mine until we get a few hundred miles to get to know it. But if I feel it is laggy, I will add a pedal box.

[Arcanum-UK]

I've fixed the throttle response from stationary. At least for me. As others find that Sport/Sport+ improves throttle response and I don't think it makes much difference, this "fix" may not work for others.

Anyway, simply turn the DSC off (the little button immediately above the sport/comfort/eco) and the throttle sharpens and is consistent. Again, for me.

My guess is that the stability control is way too conservative and whatever it does in combination with the sensors often reins the car in way too early. Turn off DSC and you get consistent, quick throttle responses.

OK, I wouldn't do this in the wet or on winter roads, but if you need to get out of a junction quickly then flick DSC off, pull out, then turn it back on again.

[edit] note that I just do a single quick press of DSC which reduces driving stabilisation. It does not turn DSC off completely. In my old M2 you could hold it down for 10-seconds to disable DSC entirely. I've not tried that in the X3 as, well, I can't see a reason to if a single press gets me what I want.

[j1980mac]

Originally Posted by Arcanum-UK

I've fixed the throttle response from stationary. At least for me. As others find that Sport/Sport+ improves throttle response and I don't think it makes much difference, this "fix" may not work for others.

Anyway, simply turn the DSC off (the little button immediately above the sport/comfort/eco) and the throttle sharpens and is consistent. Again, for me.

My guess is that the stability control is way too conservative and whatever it does in combination with the sensors often reins the car in way too early. Turn off DSC and you get consistent, quick throttle responses.

OK, I wouldn't do this in the wet or on winter roads, but if you need to get out of a junction quickly then flick DSC off, pull out, then turn it back on again.

[edit] note that I just do a single quick press of DSC which reduces driving stabilisation. It does not turn DSC off completely. In my old M2 you could hold it down for 10-seconds to disable DSC entirely. I've not tried that in the X3 as, well, I can't see a reason to if a single press gets me what I want.

It's an animal if you turn it completely off. Smiles all the way around!

[75fusca]

Originally Posted by corn18

Well, I put the pedal box on my Z4 and it made a huge difference. I put the Racechip tuner box on by itself and I think it had more oomph. Then I added the Racechip pedal box and set it to sport+ and now I have the Z4 I always wanted. The turbo lag is still there, but just driving around it now "feels" more sporty.

I'm sure this pedal box will make anyone with a lag issue on the X3 very happy. I'm not going to put it on mine until we get a few hundred miles to get to know it. But if I feel it is laggy, I will add a pedal box.

After more than a year of frustration over the turbo lag and several resets at the dealership, I finally installed the Sprint Booster a couple weeks ago and what a difference... Now it's a fun car to drive!

[corn18]

I'm reviving this thread because my M40i has gotten sick. For the first 1,500 miles or so it was a beast. Responsive, quick to accelerate in all situations. It now has 2,200 miles mostly by my wife. My wife drives like a grandma and I think she has the M40i thinking it is a Yugo. I drove it to breakfast this morning and wondered WTFO? It now drives like our old Acura MDX. Stomp on it and it sits there and thinks a bit and then gives you a half-assed effort. Sport+ helped some but even that has gone stupid.



I may have to get a Sprint Booster and install it and hide the controller and just use the app to set it. She'll never know and I'll get my beast back.

[TX3M]

Originally Posted by corn18

I'm reviving this thread because my M40i has gotten sick. For the first 1,500 miles or so it was a beast. Responsive, quick to accelerate in all situations. It now has 2,200 miles mostly by my wife. My wife drives like a grandma and I think she has the M40i thinking it is a Yugo. I drove it to breakfast this morning and wondered WTFO? It now drives like our old Acura MDX. Stomp on it and it sits there and thinks a bit and then gives you a half-assed effort. Sport+ helped some but even that has gone stupid.



I may have to get a Sprint Booster and install it and hide the controller and just use the app to set it. She'll never know and I'll get my beast back.

Try a throttle reset. I think you press the start button (without your foot on the brake so it doesn't start the car), press the gas pedal all the way down
until it hits the down-shift actuator underneath the pedal and hold the pedal down for more than 30 seconds. Then release the pedal and start the car. There are some threads on throttle reset, search and you might find one.

[harperium]

If you need a fast start, hold the brake and rev the throttle up a bit and then let go.

If you start off easy in Comfort, there's an awkward moment after you shift into 2nd where you can't accelerate quickly (being in 2nd and the RPMs around 1000-1300).

[Alias1431]

Originally Posted by harperium

If you need a fast start, hold the brake and rev the throttle up a bit and then let go.

If you start off easy in Comfort, there's an awkward moment after you shift into 2nd where you can't accelerate quickly (being in 2nd and the RPMs around 1000-1300).

I thought Comfort started off in 2nd by default?

[deladude]

Originally Posted by Arcanum-UK

I've fixed the throttle response from stationary. At least for me. As others find that Sport/Sport+ improves throttle response and I don't think it makes much difference, this "fix" may not work for others.

Anyway, simply turn the DSC off (the little button immediately above the sport/comfort/eco) and the throttle sharpens and is consistent. Again, for me.

My guess is that the stability control is way too conservative and whatever it does in combination with the sensors often reins the car in way too early. Turn off DSC and you get consistent, quick throttle responses.

OK, I wouldn't do this in the wet or on winter roads, but if you need to get out of a junction quickly then flick DSC off, pull out, then turn it back on again.

[edit] note that I just do a single quick press of DSC which reduces driving stabilisation. It does not turn DSC off completely. In my old M2 you could hold it down for 10-seconds to disable DSC entirely. I've not tried that in the X3 as, well, I can't see a reason to if a single press gets me what I want.

I've found DSC off to be much more responsive as well. The car also has much much better turn in with DSC off. I wish there was a way to code it off by default or tie it to sport individual settings.

[tonyb15re]

I had an M140i before the X3, I regularly went through the manual process of doing an adaptive driving memory reset. Havent tried it on the X3 yet but assume as they have the same engine and gearbox that the ECU works in a similar fasion, e.g. it tries to be clever and adjusts its settings based on your driving style, google it!

[harperium]

Originally Posted by Alias1431

I thought Comfort started off in 2nd by default?

Let me go check... I hadn't noticed this before

[harperium]

Originally Posted by harperium

Let me go check... I hadn't noticed this before

My M40i starts out in 1st

In Comfort it does upshift fast. By 20 mph you can in 4th rounding into 5th.

So if you mash the throttle in Comfort it's likely the RPMs are low enough that the car seems mushy. If you catch the RPMs just right though, you can have a good response.

[Njerts]

I thought the lag in BMW's are related to transmission more than anything else.
If you put it in manual mode the lag is gone.

[Alias1431]

Originally Posted by harperium

Let me go check... I hadn't noticed this before

I might be wrong, who knows. This is what I was remembering:

https://x3.xbimmers.com/forums/showthread.php?t=1533129

[harperium]

Originally Posted by Alias1431

I might be wrong, who knows. This is what I was remembering:

https://x3.xbimmers.com/forums/showthread.php?t=1533129

I googled too and there's a lot of claims that the BMW auto transmissions start out in 2nd, and maybe some do. But from my tests, it always starts out in 1st. Comfort and Eco aggressively upshift, but that's different.

True, the M40i is more responsive in manual b/c tromping the gas doesn't incur a slow shift from the transmission. But generally, when shifting manually, one tends to let the RPMs climb pretty high. The auto likes to keep RPMs from 1000-1200.

[Rhidium]

I've always hated that lag.. I'm thinking of get a Sprint Booster to give it shot.

I'm curious that if you get a bootmod3, would this fix it too?

[charlescm14]

Hey guys,

I am reviving this thread to see if you guys fixed the issue completely or still experiencing a lag ?

I want to change my 2014 28i to a 2018 M40i. I have done a lot of research and already tested 2. They felt different, both in Sport Plus mode

First one was at BMW dealership. 44k kms. I enjoyed driving it very much , a lot faster than my 28i ! I loved the acceleration it felt very responsive when I put my foot down.

Second one was at a Mercedez Dealership. 70k kms. At first the salesman didnt let me out of the parking lot , he said because it was on winter tires and its cold up here Quebec . So even in the parking lot I found that it wasnt as responsive and I put my foot down. I told the salesman It doesnt make sense to try to sell me a car by testing in the parking lot. I finally got it on the road and did a few accelerations , still not the same feeling than the first one. From a stop, I would put my foot down and it took half a second before it really went.

I didnt know about the throttle reset when I was at the dealership, I wish I did ! because that car is 3 hours away so I cant test it easily.

My question is : could it be due to other, more serious factors ? I also read that it could be a faulty gas pump ?

The second one tested had been in the cold (-30 celsius ) 3 weeks without running, and the tank was empty. Could it be due to inactivity/cold/ empty tank of bad gas ? When I told the salesman he did not know why it would feel slower than the first. He said maybe the cold , or the first one was tested was in a different setting. Maybe the salesman at the bmw dealership took off DSC without me looking . ?

The second one tested is much more to my liking in terms of trims / options / colors and price. So Im writing to you guys to see if it's worth driving the 3 hours back to test the throttle re-boot, with good gas and the car parked in the garage. Or if its a more serious problem and not worth bothering with that particular car.

Another question, do you guys have experience buying from a different dealer for your cars ? The one at the mercedez dealership is still covered by warranty , could I swing by the nearest BMW dealership on my next test drive and have them inspect it ?