Why do MCSs feel so wierd to drive when cold?

[Cooooooperslad]

Ok, I know all cars feel wierd to drive when the engines are cold, out of all the cars I've owned (even classic minis) my MCS feels worse when cold, it surges and feels like there is flatspots.

It dosn't bother me one bit as after about 3-4 miles it goes, I obviosuly dont drive the car hard when its cold. I'm just intrested why it does it and why the MCS seems to suffer worse from it?

George

[Paul]

Lots of threads on the MCS yoyo and/or stumbling, could be that "characteristic" you're feeling. Here's a few: http://www.mini2.com/forum/general-d...when-cold.html http://www.mini2.com/forum/mini-coop...o-stumble.html http://www.mini2.com/forum/mini-coop...yo-effect.html

[Nath316]

maybe coz it hasnt been really cold but my 07 doesnt really stumble i find that just let it tickover for 30 seconds and it is fine

a quick stomp on the gas once rolling and it cures

[Richard Crofts]

Its to do with what type of fuel management the car is using when you first fire up. I wont say more as its quite complicated and not of much use to many folks, plus I only have a basic grasp of it from talking to clever electronics and tuning people.

The basic thing is that it takes several minutes to get the car to settle down as the sensors that are in the MINI are not the worlds best and there are not a great number of them there to feed info to the ECU to ensure correct fuel. It is all a bit on off which makes that rather surge type feeling when cold.

Its usually nothing to worry about and its usually only seriously prominant when cold and you boot it immediatly, which is not a good thing anyhow. Turn the engine on for about 3-5 mins before you drive anywhere and it generally gets enough heat in and settles down on the fueling to make the initial dive away a bit nicer.

Also as you tune the car it seems to becomes more obvious, for understandable reasons.

Thats my inderstanding, after talking to some clever MINI tuners, of why this happens on the S more than on the Cooper/ONE

[MINI-Morgan]

I believe some of the answer is in that it takes a couple of minutes to warm up the O2 sensors so the ECU runs the engine very rich when cold until a set temp is reached and then back to good old dynamic short and long term fuel trims. Thats my understanding of it anyway.

[Nath316]

so basically

1. as soon as you get in the car start it up

2. do your usual routine ie seatbealt, stereo, etc

3. while you doing this car is resetting, warming up etc

4. drive initially slowly and let the power feed through

5, after a few mins, depending on how long it has been running standing still, drive normally

6. if car is already warm ignore 1 - 5 and go straight to 7

7. once warm drive like the hounds of hell are behind you

[Richard Crofts]

Its good practice to allow any vehicle engine to "warm" before driving hard. My personal one is;

1. Pop out to the car and fire it up and pop back to the house for all my bits and bobs and put the dog in his kennel etc. (I live in the middle of no-where up a gated private lane)

2. Drive for the first 2 miles (down the narrow back lanes to the main road) at no more than 3k rpm prefereably nice and gentle, and usually keeping the car at around the 2.5-3k in 2nd or third.

3. Hit the main road, check the engine temp guage (if its hit the mid point and been there for a some time, then between that short gentle run and the tick over before leaving oil should be warmed up enough) then stomp the right pedal and go like the clappers

[MarkW]

O2 Sensors should have fully warmed up within about 30secs of recieving a live feed, at least my Innovate LC-1 on the track car does can't see the mini ones being any different.

When ensuring your car is fully warmed up before booting it you should really use engine oil temp rather than water temp, obviously not always possible as not many cars have oil temp guages. God I love my aux oil temp guage

[Cooooooperslad]

Quote: Originally Posted by Richard Crofts (original)

Its good practice to allow any vehicle engine to "warm" before driving hard. My personal one is;

2. Drive for the first 2 miles (down the narrow back lanes to the main road) at no more than 3k rpm prefereably nice and gentle, and usually keeping the car at around the 2.5-3k in 2nd or third.

3. Hit the main road, check the engine temp guage (if its hit the mid point and been there for a some time, then between that short gentle run and the tick over before leaving oil should be warmed up enough) then stomp the right pedal and go like the clappers

Already do all this but cheers mate

[Richard Crofts]

thats cos your a country bumpkin like me

[Richard Crofts]

Quote: Originally Posted by MarkXR (original)

O2 Sensors should have fully warmed up within about 30secs of recieving a live feed, at least my Innovate LC-1 on the track car does can't see the mini ones being any different.

When ensuring your car is fully warmed up before booting it you should really use engine oil temp rather than water temp, obviously not always possible as not many cars have oil temp guages. God I love my aux oil temp guage

Yes the reason I use engine temp is at least if thats hit warm then the oil has stood some chance of getting warmed enough to at least be some of the way to being "fluid" enough to deal with my right foot I aint got oil temp yet but its in the pipeline along with some other guages and senors

Oh and its not just the O2 sensors that are the issue according to folk I have spoken to, its to do with what the cars "using" in terms of deciding fuel delivery. Eg open and closed loop. It is usually faster than 3 mins but depending on the car and other factors it can take longer than 30 seconds for a cold start MINI to "settle" and reduce the issue of surging under throttle when cold. It only really starts to disappear as the car gets nioce and warm...which takes abot 3-5 mins of tickover or gentle driving IMO from past experience. if you fire the car up and listen to it, you'll hear when it suddenly changes...the pitch of the engine changes as does exhaust note and smoothness of idle.

[iain cooper]

[quote=Richard Crofts;3176722]Its good practice to allow any vehicle engine to "warm" before driving hard. My personal one is;

1. Pop out to the car and fire it up and pop back to the house for all my bits and bobs and put the dog in his kennel etc. (I live in the middle of no-where up a gated private lane)

one of the worst things you can do to your engine is to start it from cold and leave it to tick over.

this causes massive premature engine wear, and you should always drive off asap to allow the oil to circulate around the engine and reach a reasonable temperature asap.

[Suj999]

In my last Audi A3 the instruction said "drive the car away and don't wait after starting the car" or something like that... and it said don't rev it over 3K until the engine has warmed up.

So I am thinking its not a good idea to leave it ticking over in the cold..

[Bhozar]

Quote: Originally Posted by Suj999 (original)

In my last Audi A3 the instruction said "drive the car away and don't wait after starting the car" or something like that... and it said don't rev it over 3K until the engine has warmed up.

So I am thinking its not a good idea to leave it ticking over in the cold..

MINI manual says the same thing.

[Richard Crofts]

Why would it being on tickover not push oil around same as driving it. I can see any reason that being sat on tickover for 2-3 mins does anything different in terms of getting the oil up to temp and round the engine any less or more than driving it off? If the oil is moving round the engine then the oil is moving round the engine, be it when driving at 3k rpm down the road, or at 1200rpm sitting on the drive the oil is still being pumped round by the fact the engine is running (surely the pressure in the system just builds a touch slower than if your driving, but if the revs are lower anyway the slightly slower increase in oil pressure will be offset by the lower engine speed causing less wear anyhow??? Wont it???).

I don't know enough to argue the point. All I know is its bad to rev above 3k until the oil is nice and warm/fluid. My choice for ease of things is to pop 30 feet away and leave the car ticking over for a minute or 2 to let the revs settlle down and the fueling to sort itself out before setting off at a nice gentle pace and revs before nailing it a few miles later.

I have done this in every car i have owned and I have had none that have suffered major engine/gearbox (if it has shared oil like on the classic mini) failures at low milages. Having taken many classic engines apart and several others like Rover V8s I have never seen any sign of premature wear on the engine.

I will post 1 thing up that might make a difference if the whole start from cold idle/don't idle arguement. I don't leave my cars out in the winter. They are stored in an insulated garage, so that could make a big difference in the initial thickness/temp of the oil in the car before start-up, thus meaning its at a consistency thats fluid enough to get round the engine fast enough when idling?!