[clivem2]

I'm not sure I want to start this but anyway....here goes.

Expectations with diesels probably differ from petrol engines, us oilers expect responsiveness to be not as good as with petrol engine. The are times though when my 30D feels like it has a considerable flat spot when moving off. Initially I thought it was turbo lag as this engine has a single large turbo. Then I found that in Sport there's a huge transformation, instant response. No longer is it like having an elastic band tied to the accelerator.

I drove a 35D, this was much more responsive in Normal, I had put this down to the smaller twin scroll turbo but now I feel it's more to do with programming / mapping.

Maybe it's reasonable behaviour in an effort to get good economy? Then again the 35D has similar economy.

Anyone else want to put their views across?

[Alligator69]

I share your view and with a 2.0d in a different scale the issue is alike.

[swallowtail]

I find a small amount of lag on takeoff (30d), even in Sport, but it's certainly more manageable in Sport. Spooling up turbo pressure ready to go is a little harder in an auto!

[brissim]

Yes there is a bit of turbo lag on takeoff with the 30d. But it is - in my opinion - quite manageable and certainly no worse than most turbo-charged engines (diesel or petrol) that I've driven over the years. I would assume that yes the 35d should (with what I thought were twin turbos - not a twin scroll single turbo as in the 35i petrol) improve on this. But as I say, I'm not particularly alarmed about the lag on the 30d.

Its rather academic because we don't have the X3 35d in Australia, but it would certainly be an interesting discussion on the 30d vs the 35d and probably not as clear cut as the earlier thread on the 20d vs 30d.

Tony

[clivem2]

Tony, I believe you're correct, the 35D is twin turbo, not twin scroll.

I'll be interested to hear more views as what interests me is whether it's reasonable there is more of a turbo lag in Normal vs Sport - when the car moves off both modes are using the very same 1st gear, why would turbo lag be any different? The difference has to be down to either engine mapping or throttle mapping. If it's engine mapping I can understand that for reasons of economy...I think.

[RSchneider]

Yip, you have to "precharge" him a little. I'd say the turbo lag isn't more than what it takes the autobox to shift down. But when do you really need to floor it?

Btw, I attached an interesting comparison in the German Auto-Motor-Sport magazine: It's on the lag of different versions of the diesel inline 6. They tested that in a 5 series, but it's still valid for the X3.

[clivem2]

Interesting figures. The confirm what I felt in that the 35D wasn't must faster than the 30D. I did feel it was a lot more responsive. What do the 2 graphs on the right show? KPH vs time in seconds...I don't understand the 1000 and 2500 rpm part - is it time to reach those rpms?

BTW, it's not so much about really flooring it, it's say 1/3rd throttle does little in Normal so I push it harder to get a response. In Sport this does not happen. Heaven knows what the new Eco mode is like!

[RSchneider]

Originally Posted by clivem2

Interesting figures. The confirm what I felt in that the 35D wasn't must faster than the 30D. I did feel it was a lot more responsive. What do the 2 graphs on the right show? KPH vs time in seconds...I don't understand the 1000 and 2500 rpm part - is it time to reach those rpms?

BTW, it's not so much about really flooring it, it's say 1/3rd throttle does little in Normal so I push it harder to get a response. In Sport this does not happen. Heaven knows what the new Eco mode is like!

Those two graphs on the right show the lag when you floor it at 1000 rpm and at 2500 rpm in 5th gear, how long it takes till you gain 1 or 2 km/h. But be aware that this also depends somewhat on overall gearing, tire sizes and inertia, and vehicle weight.

[clivem2]

Originally Posted by RSchneider

Those two graphs on the right show the lag when you floor it at 1000 rpm and at 2500 rpm in 5th gear, how long it takes till you gain 1 or 2 km/h. But be aware that this also depends somewhat on overall gearing, tire sizes and inertia, and vehicle weight.

So the 30D actually shows as being a little more responsive at low revs than the 35D engine.

BTW, the issue I'm talking about is intermittent, I can't reproduce it on demand but it's always from a standstill of several seconds when I would expect the turbo to have spun down. Maybe BMW keep the turbo spinning somehow (F1 blown diffuser :-)) and it's only when it's total stationary that my issue happens.

[clivem2]

Follow up question, are those graphs for M, S or S+ mode?

[khaiql]

I also find the throttle in normal mode lethargic and I also have to push the throttle harder to get any movement. Throttle lag is almost non-existent in Sport mode by comparison but it is still noticeable. Quickest standing start by seat-of-the-pants impressions is to enable auto-hold, Sport mode and nail the throttle.

[RSchneider]

Originally Posted by clivem2

Follow up question, are those graphs for M, S or S+ mode?

No idea. But does it make a difference? Boost onset should be the same in all modes, just manifold pressure *could* be different (though I don't think so). The sporty modes are more a e-throttle and gearbox thing I think.

[clivem2]

Originally Posted by khaiql

I also find the throttle in normal mode lethargic and I also have to push the throttle harder to get any movement. Throttle lag is almost non-existent in Sport mode by comparison but it is still noticeable. Quickest standing start by seat-of-the-pants impressions is to enable auto-hold, Sport mode and nail the throttle.

I agree, and I suspect it's even better in Sport+ with less traction control interference, not in the wet though!

[clivem2]

Originally Posted by RSchneider

No idea. But does it make a difference? Boost onset should be the same in all modes, just manifold pressure *could* be different (though I don't think so). The sporty modes are more a e-throttle and gearbox thing I think.

I think this in the nub of the discussion here. In Normal the car feels somewhat dead vs Sport. So how have they done this,? It's a lot more that autobox change points and it impacts pulling away from stationary. Do BMW delay the effect of throttle movements in Normal or maybe deliver increases in fuel gradually to give the car more economy? Some of these things will result in less manifold pressure than in Sport.

[RSchneider]

Originally Posted by clivem2

I this in the nub of the discussion here. In Normal the car feels somewhat dead vs Sport. So how have they done this,? It's a lot more that autobox change points and it impacts pulling away from stationary. Do BMW delay the effect of throttle movements in Normal or maybe deliver increases in fuel gradually to give the car more economy? Some of these things will result in less manifold pressure than in Sport.

Since I don't think that BMW quotes different times to speed, or max speed in different modes I'd say it's mostly throttle trickery.

[clivem2]

Originally Posted by RSchneider

Since I don't think that BMW quotes different times to speed, or max speed in different modes I'd say it's mostly throttle trickery.

Yes...but I can't believe 0-5 kph measure the same in Normal and it does in Sport. It may well be throttle trickery but it has a big effect.

Maybe they quote economy in Normal and performance in Sport. They must quote performance for tests in Sport or Sport+, the higher change up points of the gearbox will make the times faster.

[Nad]

Is the throttle response issue still present in the 2013 models?

Nad

[clivem2]

Originally Posted by Nad

Is the throttle response issue still present in the 2013 models?

Nad

I'm not really sure it is an issue such as exists or existed with the petrol models. I'm sure BMW would say it's a characteristic of the vehicle. It may well be to be fair. To get the economy figures they have it can't be sporty all the time. I was trying to get views on what others thought.

I know that from driving a 1 series with Eco mode that it's truly horrible but maybe it brings great economy.

[dnw]

I can't say I notice this issue at all on my March build 30d... and I do like to play with it

In normal mode, it is perfectly fine off the lights with foot down. In sport, it is even better.

I wonder if the issue is more to do with the ZF transmission mappings. There has been a lot of reports of a software upgrade for the petrols, perhaps the same applies to the diesel engines and mine has this already?

[Horsey]

Cant wait for my 35d

[Ant Man]

Originally Posted by clivem2

I think this in the nub of the discussion here. In Normal the car feels somewhat dead vs Sport. So how have they done this,? It's a lot more that autobox change points and it impacts pulling away from stationary. Do BMW delay the effect of throttle movements in Normal or maybe deliver increases in fuel gradually to give the car more economy? Some of these things will result in less manifold pressure than in Sport.

I doubt the throttle lag has anything to do with the gearbox as lag should be present when keeping the car in the same gear.

Tuners alter various maps when remapping which can include vanos timing and changing the ignition timing. Also with these fly-by-wire throttle a certain amount of pedal movement is engineered to have a non-linear response to the throttle to aid economy / Co2.

I would be confident that the sport setting runs a completely different map with the main purpose to reduce throttle lag and make the engine's response more spontaneous. All turbo diesels with single turbos suffer from lag to an extent but some drivers don't even notice.

I can't recall if the twin turbo 35d uses the smaller turbo at low revs and the larger turbo at high revs or vice versa. Apparently the turbo 1M has very little (some say no) turbo or throttle lag, though it's petrol. BMW tri-turbo diesel as used in the m550d is reported to be very good too for a more spontaneous throttle response.

I can't stand throttle / turbo lag and much prefer the purity of NA petrol so I'd be very keen if you ever drive a 35d and post views of how it compares to the 30d. You seem to tell it how it is. Having yet to test drive the new X3, I think I'll be going for the 35d, not because of the performance but more to do with how it drives and feels with regards to responsiveness. Though I should say 'theorectically' as I need to drive both 30d and 35d before confirming my assumptions.

[swallowtail]

I have noticed a couple of times in the last few days where I have booted the 30d to get into a hole in the traffic, and it's done nothing..... then goes. Gave me a fright on one of those LOL. In Normal it keeps the revs very low (for economy presumably), but it does drop it below the turbo's boost range. It's a lot of car to push around for what effectively becomes a NA diesel below 1500rpm... until it reaches about 1500 and the turbo spools up. In Sport it is definitely better, but primarily I think because the revs are held higher.

I need to get into the habit of kicking into Sport or DS before getting ready to go in that instance.

We don't get the 35d here in Aus. Would be interesting to see if any of the tunes that are available can assist with 1000 - 1500 rpm responsiveness, but that would probably be at the expense of fuel economy.

My last car was a NA 3.6L V6 that pulled from idle to 7000rpm in one long constant surge (VW Passat R36 - 220KW) and was far more instant, progressive and reassuring from a "push the loud pedal and watch it go" point of view, but the 560NM of torque of the 30d is certainly entertaining once it gets its skirts hitched up and going. Just needs some re-adjusting in terms of expectations and driving behaviour.