Starting/Stopping engine with Air-Conditioning and Radio on

[dmi3]

Hi y'all ...Quick question ....I dirive a 323i with the engine start stop button . when picking up my car , the SA told me that i do not have to switch off the air-conditioning or radio and just start and stop the engine as and when i like . He claimed that it does not 'kill the car' especially when starting since the air con compressor only kicks in after the car has fully started ...I come from a very traditional school of thought... that when u start ur car , the air-con especially needs to be off not to kill ur batt especially ... any one of you can shine some light as to whether its ok to start the car with everything on ? It does not feel right after years of telling myself to switch off the air con . I think the SA might be right since there is no way to off the air con other than decreasing the fan speed ...and that seems troublesome ...comments ? dmi3

 

[Schwepps]

You're not alone. Lots of people keep trad ideas or bring forward experiences from their first few cars, usually national or jap. But trad equals old or basic, times when everything was mechanically controlled. Your BMW is almost totally electronically controlled by your OBC (on board computer), even whether to let you in and start the car. It even keeps one set of settings for one key fob and another set for the other.

You can be assured that your car won't clutch in the AC compressor until the engne is ready for the load.

 

[dmi3]

ok ....start stop without caring bout anything at all ...

heck ...the fact i dont have to worry about switching the lights off is just blady awesome ...to add AC and stereo to that ....pure bliss

 

[Schwepps]

Yeah man, think of it... Your OBC already decides when it's dark and the lights should come on, what spark timing to set based on the gas you pump, how fast to change gears based on your driving style, which wheel to brake when you corner too fast, etc, etc. Other models wake you when you're nodding off, change suspension settings based on speed and turns, side park your car for you with your hands off the steering and feet off the pedals, etc, etc.

And there's more automation already developed and waiting to be launched in future models! :top:

 

[Ennui78]

You think you're a stickler to tradition........this is how much of an anal-retentive OCD freak I am.....I start to suck up furniture!

To turn off my car engine:

Step 1: Turn off Airconditioner

Step 2: Turn off Radio.....please turn volume knob until you cannot hear anything. Strain your ears by stretching side of neck to open ear canal to maximum limit if unsure.

Step 3: Fold in Mirrors

Step 4: Turn off lights.

Step 5: Turn off Engine after ensuring revs are stable...if not, wait...and wait and wait until RPM lies between 700-800.

Exit vehicle! Yay......all in a day's work. (Breathes inwardly, sigh of contentment)

 

[Grand]

To each their own. Well, after all, its a matter of peace of mind for yourself. If you feel better switching off everything before you off or on your car, just do it. There will be no harm done to your car. Similarly if you want to leave everything on before you off or on your car, for our UDM, there will be no harm so just do it. Don't feel constrained to follow others' practice just because "everybody else is doing it" unless of course, your practice is proven to be harmful to your vehicle. Similar argument (or dilemma?) in respect of whether you should change to "N" or leave your gear at "D" at the traffic light.

 

[dmi3]

Ennui78 ...ur process is so tedious .....i suggest u just try stopping and starting once without switching nething offf ....its sooooo fun . It takes time to get used to but after a while you will find it convenient.

As as now , I am quite convinced that there is no harm done to the cars in any way since most of the sifu's here do it also
Thanks y'all...

 

[viewfinder]

I dont know which model onwards, but E46 definitely has electronically controlled power on / shut down sequence to ensure transient voltage/current spikes are being staggered. BMW has electrical engineers and software engineers on their pay rolls too, not just mechanical engineers. Having said that, that applies to stock standard or BMW spec accessories but if anyone adds/modifies something (maybe ICE stuff) then I have no idea.

ps you need not do staggered power on / shut down sequence on your desktop/laptop/etc as well

 

[Schwepps]

Similar argument (or dilemma?) in respect of whether you should change to "N" or leave your gear at "D" at the traffic light.

IMO this is a purely mechanical issue, as there's no electronic override for the torque converter when your selector is in D and your foot is on the brake. It's simply one mechanical force acting against the other. No harm will be done if you stay in D, but IMO wear and tear will be accelerated. I shift to N at traffic lights...the creep in a 325i is pretty strong.

Similarly I do slow down for speed humps and badly ridged sections of roads to save wear and tear on the suspension. Maybe my driver doesn't, because I've just changed one cracked suspension arm and related joints and bearings in the Merc. Cost...RM5,400. Premium car parts are not cheap.

 

[gameover]

I don't know about you guys but my E90's AC will only be on fan at 1 bar when the engine starts, after around 15-20 seconds the AC recognizes that the engine is at normal speed and it'll then go up to the whatever speed you left it on. So yes the electronics are pretty clever.

Here's the next question, do you "warm up" your engine or do you drive off immediately?

 

[Schwepps]

This has been discussed many times. Warming up at idle is actually detrimental because it takes longer, oil circulation is minimal, and only the top-end of the engine gets warmed up, leaving out the rest of the drivetrain. All manufacturers recommend that you drive off immediately but gently for the first few km.

 

[dmi3]

thats right ...you should drive off but go slow in the beginning . i think i even read this in the owners manual ...

 

[whymahn]

yep. the manuals said drive off immediately and at slower speeds.

 

[gameover]

This has been discussed many times. Warming up at idle is actually detrimental because it takes longer, oil circulation is minimal, and only the top-end of the engine gets warmed up, leaving out the rest of the drivetrain. All manufacturers recommend that you drive off immediately but gently for the first few km.

Heheh I know actually, that's why I put warm up in quotes, and like what dmi3 said, it's even in the manual. The thing is there are people who still believe they need to warm up the car which I don't understand...

 

[Schwepps]

It is hard to separate fact from legend sometimes, when it comes to dos and don'ts. I notice that on mass market cars, the fan blower comes on when you turn the key to ignition position, even before you start the engine. Questionable whether the AC compressor is sequenced then. In the E90 it's definitely sequenced and even the blower won't kick-in until a few seconds after starting the car.

 

[wz3k]

in my honda civic and city, i never turn off a/c or radio before i shut down the engine. When i start the car, a/c and radio will be on first then the engine will be started. No big issue.. but I do change my battery every 1.5 years as I notice the battery is weaker already (can hear by the sound when engine start).. I never wait until the battery fail.. no regrets because battery is only RM200 for my honda..

BMW is another story..battery more expensive.. but then again, the on board computer is definitely much smarter..

 

[zeedo]

I think its good to switch off a/c and radio to reduce the start-up load and prolong battery life. But it depends on preference anyway