[PrideRed]

Most of cars these day come with drive modes. Simply toggle some buttons and you can see significant difference in each mode. While most manufacturers stick to City/Normal/Sport, what they don't tell us is the underlying behavior. Some reviews say there is changes to engine response, shift, steering response and even AC, but there is no word from manufacturer. Not sure if finer details is mentioned in Manual but I haven't heard anyone speak much about what happens underneath when I click these button.

Is this some simple changes to ECU? Is there difference in BHP/Torque when I toggle modes? Is the implementation different in each model or manufacturer?

[alpha1]

In the olden days, when we pressed the accelerator pedal - what used to happen?

The accelerator pedal controlled the opening of the throttle valve on the air intake.
Due to the carburetor venturi action, gasoline gets sucked in and sprayed as a fine mist into this inrushing air going to the engine for combustion later.

You could tune the carb so that for the same throttle opening less gasoline would be sucked in and sprayed, or more - depending on your preference.

With the proliferation of programmed fuel injector which uses microprocessor replacing the mechanical equipment called carburettor, this "tuning" facility was robbed off.

The eco mode / power mode is one way to address it. Eco mode meters out less gasoline compared to the power mode, therefore you can turn your vehicle from a gasoline guzzler to mile cruncher (well the effect is not that dramatic, since your engine remains the same and there are physics dictated upper and lower limits to the amount of gasoline that you can inject in an engine).

[srini1785]

Originally Posted by PrideRed

Is this some simple changes to ECU? Is there difference in BHP/Torque when I toggle modes? Is the implementation different in each model or manufacturer?

Attachment 2091692

Its everything to do with ECU. With the flip of a switch a new set of data is loaded into the ECU and it alters the way power is produced in the engine by altering say the AFR , turbo boost etc. The overall max values of torque , bhp remain the same and only the way it is delivered differs in these modes.

[Nalin1]

What about terrain modes like, mud, snow, sand etc?

How different/similar are these to normal/sports modes? Or do we start another thread on those?

[Rachit.K.Dogra]

Many years ago, VW India had organized a contest in India around Innovative ideas for cars. I had recently changed the CDI of my Karizma and was reading through some of the theory around Ignition timing, flame propagation and how it can alter engine behavior and thus power produced.
In those days, a few sports cars came with only a dedicated sports mode and this technology was not available in mass scale products.


I had submitted the idea of making this technology available to mass scale products there by increasing the appeal of a product to a wider audience. Only probably 2nd time in my life I felt, my idea was worth something . I am not trying to own this thing because I am pretty sure I was already 2-3 years late and this was already in the drawing boards of many car companies by then. Its just that it had not gained popularity by then.

Earlier it was only multiple ignition maps loaded in car ECUs and each mode selected a corresponding map from the ECU. In simple terms these maps can vary from each other in terms of Air Fuel mixture ratios (When to run an engine lean and when to run an engine rich), Ignition timing etc.

But as technology has progressed and as this piece of technology has progressed, I am sure many car companies have these varied parameters in their mind while in the design phase of the car only. The availability of much higher processing power in cars allows more control and variations of some more parameters now like gear shift timing, adaptive damper control, electronically controlled roll bars, traction control and ESP etc. Also with the gains in technology in engine design and with more and more boosted (turbo charged) engine, engine can be made more flexible to deliver different behaviors at same rev range but still work optimally.


Rachit

[humyum]

I think drive modes in the everyday cars in India change only the throttle response, something like what a pedal commander does giving you a sense of urgency with little accelerator input in sports mode against a lethargic throttle response when kept in eco mode with the same pedal input.

Like for example, after 12 years of owning it I discovered in my Swift Diesel that at low rpms say at 1500 rpm and 5th gear if I pressed the accelerator to half it did nothing but increase the rpms and speed at the same pace as it did when I pressed it at 30 % accelerator input. All these years, I assumed that with these parameters even if I pressed at 100%, the response would be still the same as 30% and 50%, but NO. Some weeks back I was just cursing around on the highway and did this small test, at 30% and 50% it was same urgency, but the moment I pressed it 100%, there was an increase in acceleration and an unnatural shove more than what I got at 50%. You learn something new even after all these years eh?

I think the sports mode gives you that urgency, the eco mode takes it away at various accelerator pedal inputs, the torque and bhp of the engine remains the same. This is when it comes to the engine.

With other parameters like steering become hard in various sports modes = Varying the power steering assist depending on the modes

Dampers - Dampers hardening up like the manual damper settings are in the Duke depending on the mode you select to get better cornering capability.

[Samba]

For off road-
ECU detects the wheel grip according to the terrain and supplies power accordingly.
Grip level differs in mud/slush, snow, sand, rocks. Hence different modes are given.

A good experienced driver can replicate any of these with his right foot. Correct accelerator modulation is whats needed.
I have seen an old jeep with no electronics in the hands of a good driver getting through, whereas a new gen SUV with all the bells and whistles getting stuck with a newbie driver.
Inexperienced drivers definitely get benefited from these modes. Am not against these modes, these definitely gives the driver some room for error on off-road.

For tarmac-
In ECO mode, the fuel supply and the optimum power of the vehicle is tuned down, whereas is in normal or sports mode the optimum power is been supplied.

With perfect throttle input the mileage of ECO mode can be replicated in normal mode too. I have done this many times. I hate driving in ECO mode, the car feels under-powered.

[Cessna182]

Originally Posted by alpha1

The eco mode / power mode is one way to address it. Eco mode meters out less gasoline compared to the power mode, therefore you can turn your vehicle from a gasoline guzzler to mile cruncher (well the effect is not that dramatic, since your engine remains the same and there are physics dictated upper and lower limits to the amount of gasoline that you can inject in an engine).

Simple and crisp explanation. Thanks. The switches are going to regulate the air fuel ratio in the combustion chamber.

In some cars like the XUV300 the power steering motor sensitivity also gets changed. This is easily done with an electric power steering. In the rc airplane remote controls we have a similar switch to change the sensitivity of the servos operating the rudder, aileron and elevator. Same principle applies here.

As for the 4 wheel drive or all wheel drive settings, it controls the torque distribution through the differentials (in addition to other parameters like selective braking for better traction).

I'm curious to know about any real world mileage improvement achieved after activating these modes for cars with just the air fuel ratio modification setup.

[Jeroen]

Lots of cars have these different drive modes these days. And although the abbreviation roughly tend to mean the same stuff, different manufacturers have different ways of implementing the stuff. But all have one commonality, which is usually that changes are made in to the power train and or suspension by means of setting different parameters in the ECU and or other computers (e.g. Body Control computer).

Although it is pretty common to see these on many cars, a lot of this was available on more high end cars 20-30 years ago.

My 2002 Jaguar XJR has a power mode: When I press it three things change:

- This car has massive 4.0 V8 Supercharged engine, in normal mode it always pulls away in second gear, cause its got bags of torque. With the power button pushed, it also uses first gear for even faster acceleration.

- The Power setting also changes the way the autobox shifts gear, essentially it keeps the revs up, so changes later when accelerating.

- This car is equipped with active suspension. Pushing the power button stiffen ups the suspension and also ensures less body roll.

So in the case of my Jaguar, no changes as such on the ECU as such, but on the TCM and the BCM. But it is all done through software that changes the behaviour of certain car components.

Without the power button pushed my Jaguar is not exactly a slouch and will give most modern cars, still, a run for their money.

But with it pushed it becomes ridiculously fast. We are talking about a 20 year old, 1800 kilogram, sedan, cruiser, going 0-100km/h in just 5 seconds. 100-250km/h is done leaving any Tesla in my wake.

I rarely used the power button, only when the occasion calls for Hyperspeed!

Jeroen

[landcruiser123]

The cars use three different ECU (and TCU for ATs) maps (in the case of eco, normal, and power). Previously, manufacturers had one tune which was a happy balance between power, efficiency, & reliability. (I'm sure using these modes shouldn't affect your long-term reliability.) I think most of them are highly gimmicky to get slightly better rated FE.

Most 'eco' modes have a dull throttle response compared to the most aggressive throttle response of the 'power' mode. I wouldn't be surprised if your car buying contract had a small part of T&C which would explain ARAI FE is obtained with 'eco' more and rated horsepower in the specifications is in 'power' mode.

As you go up in segments, there are settings to adjust other components like: steering tightness, suspension dampening etc if your car have the expensive hardware.

Originally Posted by Nalin1

What about terrain modes like, mud, snow, sand etc?

I think those are slightly different and use inputs from various sensors connected to the ABS & BCM (body control module) systems to limit wheelspin & slipping.

They can be highly effective in 4WD & AWD vehicles, but have limited uses in 2WD vehicles IMHO. Thread: https://www.team-bhp.com/forum/techn...-2wd-cars.html (How useful are the Terrain Modes of 2WD cars?)

[ButterRider 7]

Different road conditions demand different driving characters of the car. The car drivers have different driving styles and they need to adapt to the road conditions. Some drivers prefer a sporty drive while others prefer a comfortable drive. The modern cars are capable to deliver diverse performance range according to the driver’s demand. These cars offer Driving Modes through which the driver can change the car’s driving character. The Engine Control Module controls the car’s main components such as the engine, transmission, suspension, steering, and brakes. It has different power maps for different driving conditions. Driving modes also alter the throttle response, suspension stiffness, steering feel, and traction control. The earlier generation cars had the single driving characteristic. With driving modes, you can drive and handle a modern car in multiple ways for instance, three driving modes will give you the performance of three cars in one.

[QuadraticAmoeba]

From my (limited) driving experience on my car, I see two things:

- gears shift at lower rpm in normal vs. sport mode (I think about 1700 vs. 2000 for my car)
- response to flooring the accelerator is faster in sport mode and the car feels faster to “take off”
- steering wheel gets stiffer

This is, of course, talking about the end user experience and not what happens under the hood.

I didn’t notice a huge difference between eco and normal mode, but then I haven’t used eco mode much.

[saikarthik]

Originally Posted by alpha1

The eco mode / power mode is one way to address it. Eco mode meters out less gasoline compared to the power mode, therefore you can turn your vehicle from a gasoline guzzler to mile cruncher (well the effect is not that dramatic, since your engine remains the same and there are physics dictated upper and lower limits to the amount of gasoline that you can inject in an engine).

Yes, your explanation is drilled down to the fundamental of how much fuel to inject is right.
This is done by calibration by a EMS software calibration engineer. They do drivability, gradeability, and emission trials and create a fuel map or table, which in-turn in implementation goes as injector actuation timing (how long the injector is open @certain pressure to inject how much cc of fuel)

Now it has on one side the RPM and other axis the load on engine (or Throttle position), based on the calibration and extensive trials the engineers arrive at a map to either produce more power or more FE but meeting the emissions. So the difference is small in our regular engines because you need minimum drivability in even eco mode (example - you need power to overtake), and for power mode you need to pass the emission regulations with same hardware. So they have multiple maps. You get to select the pre-defined maps based on the switch ECO/POWER.

Now there are complex things behind calibration like temperature compensation of air intake and other, but lets keep it simple.

Example of a Fuel table defining the AFR (air fuel ratios).



A 3D map showing Ignition timing as well:

Originally Posted by landcruiser123

Most 'eco' modes have a dull throttle response compared to the most aggressive throttle response of the 'power' mode. I wouldn't be surprised if your car buying contract had a small part of T&C which would explain ARAI FE is obtained with 'eco' more and rated horsepower in the specifications is in 'power' mode.

I think those are slightly different and use inputs from various sensors connected to the ABS & BCM (body control module) systems to limit wheelspin & slipping.

Good question on the ARAI FE.. Can someone shed light on this? But I can assure that in ARAI the emission tests are performed in highest power output map also.

As for the terrain modes, it has to do more with traction control and ESP. ABS units cannot perform this as the computing power in the microprocessor is not high and also the pump used in ABS is a smaller one to brake on its own.
Also, this is achieved not just by braking but also modulating the torque request from engine based on wheel speed sensors (slippage)

[JediKnight]

My car ( Mahindra Marazzo ) comes with an "eco" mode. I never use it. Reason being:

1. Effect on engine longevity. I have a feeling that the "eco" mode may not have been tested as thoroughly as the default mode. If you search the forum you can find an Innova Crysta engine failure and the OP was using "eco" mode extensively.

2. It is useless. You can achieve the same result as "eco" mode by driving with a light foot.

3. Muscle memory calibration. When i drive a car my body also calibrates itself to the car. If i change the driving mode to "eco" mode my body needs to re-calibrate itself to the different vehicle behavior. So if i frequently keep shifting modes my body may not get enough time to optimally drive the vehicle.

[TrackDay]

Originally Posted by JediKnight

My car ( Mahindra Marazzo ) comes with an "eco" mode. I never use it. Reason being:

1. Effect on engine longevity. I have a feeling that the "eco" mode may not have been tested as thoroughly as the default mode. If you search the forum you can find an Innova Crysta engine failure and the OP was using "eco" mode extensively.

Is this true or Backed up scientifically ? I have a habit of using Eco mode usually when I drive as I am mostly a sedate driver.

Can anyone else also explain the drawbacks of using such a mode, especially for prolonged use ? Car in reference here Honda city (5th Gen). Other cars are also welcome.