[Ganeshbabu2008]

In the case of auto box, I’m assuming that the braking process is split it two parts. The first part where the auto box down shifts to use engine braking alone and then the 2nd part when the actual braking begins to activate. Is the transformation from the 1st part to the 2nd seamless or is there some kind of indication available there? Thx.

[HighlandPete]

Originally Posted by Ganeshbabu2008

In the case of auto box, I’m assuming that the braking process is split it two parts. The first part where the auto box down shifts to use engine braking alone and then the 2nd part when the actual braking begins to activate. Is the transformation from the 1st part to the 2nd seamless or is there some kind of indication available there? Thx.

Certainly the auto will down change on decceleration, but not to give effective engine braking, but to put the car in a gear where the engine speed is above idle, the revs typically only rise a few hundred rpm and it is a gentle stop.

Using the brakes briefly will intitiate engine braking. On a descent a quick dab on the brakes will instigate a down change, or two, if the brakes are dabbed hard enough. The box then typically holds the gear until you add a bit of throttle, to show you are wanting an up change.

Also going downhill the 'box will change down, if the car speed increases, thus enhancing the engine braking effect.

HighlandPete

[glitched79]

If engine braking isn't really a factor on the N20, what's happening when I press the decelerate switch on the steering wheel when cruise control is engaged?

It definitely seems to slow the car down WAY more than just letting up on the gas pedal does without cruise engaged.

Does the cruise actually engage the brakes if you press down on the decelerate switch hard enough?

And if so, do the brake lights come on?

[Feanor]

Originally Posted by glitched79

If engine braking isn't really a factor on the N20, what's happening when I press the decelerate switch on the steering wheel when cruise control is engaged?

It definitely seems to slow the car down WAY more than just letting up on the gas pedal does without cruise engaged.

Does the cruise actually engage the brakes if you press down on the decelerate switch hard enough?

And if so, do the brake lights come on?

I've been wondering how this works on the new cruise with brake function. I want to be able to let the car slow down by itself by reducing the cruise speed setting as I do at the moment. I don't want to waste fuel by the car applying the brakes unecessarily. If braking is needed I'll take control myself.

[HighlandPete]

Originally Posted by Feanor

I've been wondering how this works on the new cruise with brake function. I want to be able to let the car slow down by itself by reducing the cruise speed setting as I do at the moment. I don't want to waste fuel by the car applying the brakes unecessarily. If braking is needed I'll take control myself.

Brakes are applied if you overrun the set speed. Strange sensation, when it happens on my 330d. I also agree on not wanting to waste fuel.

HighlandPete

[Ganeshbabu2008]

Originally Posted by HighlandPete

Certainly the auto will down change on decceleration, but not to give effective engine braking, but to put the car in a gear where the engine speed is above idle, the revs typically only rise a few hundred rpm and it is a gentle stop.

Using the brakes briefly will intitiate engine braking. On a descent a quick dab on the brakes will instigate a down change, or two, if the brakes are dabbed hard enough. The box then typically holds the gear until you add a bit of throttle, to show you are wanting an up change.

Also going downhill the 'box will change down, if the car speed increases, thus enhancing the engine braking effect.

HighlandPete

Thx for that, pete. I was wondering how the auto box would control the linearity during engine braking and you've explained it well. I guess after elimination of the engine drag, double gear downshifts are not necessary during engine braking to work up the crank pulley.

[wayman519]

this is all part of the efficient dynamics. Somehow in sport mode i notice the engine brake is much more noticeable once foot leaves throttle. As for the rest of the driver modes the engine braking is reduced to allow for maximum coasting thus better fuel efficiency.

[SomeRandomer123]

Originally Posted by HighlandPete

Brakes are applied if you overrun the set speed. Strange sensation, when it happens on my 330d. I also agree on not wanting to waste fuel.

HighlandPete

I read somewhere that only the rear brakes are used when cruise control is decelerating. Not sure how truthful that is, but it is definitely a strange sensation.
Eee, back in our 330d days! Good times

[Harrys6MT]

I agree with all but does anyone had an issue when engine braking stopped working? Mine did and I can’t figure out why. Dealer can’t either.

[thejeremyman9]

Originally Posted by Harrys6MT

I agree with all but does anyone had an issue when engine braking stopped working? Mine did and I can’t figure out why. Dealer can’t either.

This thread is nearly 10 years old and what do you even mean engine braking stopped working...?

[HighlandPete]

Originally Posted by thejeremyman9

This thread is nearly 10 years old and what do you even mean engine braking stopped working...?

I'm also wondering what that means... stopped working...?

[Wires]

+1 on that!

Unless he's talking about the lockup converter isn't locking anymore, so you tend to get less drag coming to a stop.

[dmaxdmax]

I'm glad someone bumped this as I've learned maybe I shouldn't engine brake as much as I used to in my e46. I have a steep hill near me, 2nd doesn't hold the car, and if I drop to first, the car sounds like it doesn't like revving to 5k rpms. Guess I'll just use my brakes more.

[Icarium81]

I noticed and posted the same thing within a month of ownership on our car, every other vehicle I've driven has had noticeable engine braking, whether auto or manual, the bummer though was almost non existent until you started dropping 3 or 4 gears and pushing the tach almost to the red line.... hardly a good compromise.

[Wires]

Originally Posted by Icarium81

I noticed and posted the same thing within a month of ownership on our car, every other vehicle I've driven has had noticeable engine braking, whether auto or manual, the bummer though was almost non existent until you started dropping 3 or 4 gears and pushing the tach almost to the red line.... hardly a good compromise.

The ability for it to "sail" as they call it substantially reduces fuel consumption.

As much as I downshift all the time and let it engine brake, its the wrong approach in most situations. Brake pads are cheap and easy to replace, transmissions and clutches are not.

[Harrys6MT]

Originally Posted by Wires

+1 on that!

Unless he's talking about the lockup converter isn't locking anymore, so you tend to get less drag coming to a stop.

Originally Posted by Wires

+1 on that!

Unless he's talking about the lockup converter isn't locking anymore, so you tend to get less drag coming to a stop.

That's what I don't know what happened. My car was perfectly slowing down with every downshift before my 50k service and now it just sails when downshifting. Rpm's rev up but the car just keeps sailing. I know a lot of folks are experiencing this but that's not how it should be. At least wasn't in my case and it was perfectly driving like a normal stick shift car. I do not know what a lockup converter is and would look into it.

[Harrys6MT]

Originally Posted by Wires

The ability for it to "sail" as they call it substantially reduces fuel consumption.

As much as I downshift all the time and let it engine brake, its the wrong approach in most situations. Brake pads are cheap and easy to replace, transmissions and clutches are not.

Originally Posted by Wires

+1 on that!

Unless he's talking about the lockup converter isn't locking anymore, so you tend to get less drag coming to a stop.

Agreed. Why would you rev up unless the car slows with it. I have the same issue and I hate it. There has to be a fix to this. I bet there is some setting in there because it was perfectly slowing with downshifting for me earlier before I got a service done.

[Heel328]

I have a 6-speed and downshift a good bit for braking, but you're right it certainly doesn't slow the car down like older cars. I pump the gas a tic to rev-match. Last time I had a 340i loaner I noticed downshifting slowed the car noticeably more than my 4 cylinder.

[Harrys6MT]

Originally Posted by Heel328

I have a 6-speed and downshift a good bit for braking, but you're right it certainly doesn't slow the car down like older cars. I pump the gas a tic to rev-match. Last time I had a 340i loaner I noticed downshifting slowed the car noticeably more than my 4 cylinder.

That's what I am trying to get at - reduction in speed when I down shift but something went wrong and it does not do it any more. I wish someone on this forum forums the technical issue and got it fixed?

[HighlandPete]

Originally Posted by Harrys6MT

That's what I am trying to get at - reduction in speed when I down shift but something went wrong and it does not do it any more. I wish someone on this forum forums the technical issue and got it fixed?

You are saying you downshift, revs increase, but you don't slow down. Assuming the throttle is going back to zero position, it would indicate the ECU is still fuelling the engine. Otherwise it must slowdown.

What's the equivalent of the old 'swingometer' indicating mpg wise? Any other abnormalities? Like revs hanging on, rather than dropping fast, back to idle?

[Wires]

Originally Posted by Harrys6MT

That's what I am trying to get at - reduction in speed when I down shift but something went wrong and it does not do it any more. I wish someone on this forum forums the technical issue and got it fixed?

If you drive around in 1st gear (manual mode) and really slow speeds, do you get that manual transmission "chug 'n' jerk"? The car should lockup the torque converter so it "feels like a manual" at that point.

I'm willing to bet what you are missing is the converter locking up which usually adds 10% more engine braking due to it bypassing the converter slippage losses.

Just a thought... does it act the same in all modes? Maybe comfort/eco doesn't lock, but sport/sport+ does? I drive sport 100% of the time so I haven't paid attention to the other modes.

[thejeremyman9]

Originally Posted by Wires

If you drive around in 1st gear (manual mode) and really slow speeds, do you get that manual transmission "chug 'n' jerk"? The car should lockup the torque converter so it "feels like a manual" at that point.

I'm willing to bet what you are missing is the converter locking up which usually adds 10% more engine braking due to it bypassing the converter slippage losses.

Just a thought... does it act the same in all modes? Maybe comfort/eco doesn't lock, but sport/sport+ does? I drive sport 100% of the time so I haven't paid attention to the other modes.

Eco shifts to neutral on decel so there will be zero engine braking.

Also, if you guys think something is wrong, you can datalog decel and see what it looks like (TPS, AFRs, load target, etc)