Riad

I think we all agree not to let you car idle until the temp rises.

My engine runs rough when it's cold, almost like it has bad gas (but not that bad) and my 2001 did the samething. As soon as the idle hits 700rpm it purrs like a kitten.

I really don't need to be anywhere 2 minutes faster, so why not?

Doug&Julie

Well now I'm very curious, too. I was told what I was told and it made sense to me when I was told...and I'm sure I was told by an "expert". I'd love for an engineer to chime in here and set us all straight...

911mz

I tried to keep the car under 3000 RPM right after I start the engine and it didn't work out very well, I didn't let the car warm up first, I just drove off, the car stalled pretty bad on 1st 2nd and 3rd gear, feels like engine is shutting off, from another article I read few days, if your car stalls then it means you need to let it warm up a little bit.

Fred R. C4S

The mixture needs to be a little rich at cold temperatures to provide enough fuel for combustion. At cold temperatures, some fuel condenses in the intake tract. This effect is similar to the use of a choke on a carbureted engine. Running a bit rich at elevated speeds also helps to heat the catalyst up faster to reduce start-up emissions.

Unless its below 0 deg, I can't see the value in sitting for 3-4 minutes to allow the engine to drop from cold high idle.

Cheers,

RJFabCab

Interesting discussion. I'm no engineer, but here's my reasoning:

Fuel has a flashpoint. On cold days, you have cold fuel... assuming that the composition of the fuel hasn't changed, the specific flashpoint should be no different, however, the amount of energy required to reach that flashpoint is increased. Running a little rich on cold startup should increase your chances of achieving combustion and thus achieve startup.

Now that I'm thinking about this, does cold weather significantly increase the fuel flashpoint due to moisture condensing within the fuel?

Engine emissions are reportedly worse on startup and at idle. Running a higher startup idle is not only the result the richer condition, but it also helps to get the cats warmed up to help further reduce emissions.

I think that the manual recommends driving right away in an attempt to reduce overall emissions, especially idling emissions, and to reduce the chances of emissions toxicity (e.g., letting your car idle in an open door garage).

Riad

I think everyone's on the right page here. Definitely the choke on my snow blower serves the same purpose, but I always wait for that engine to warm up before I start throwing snow!

Keep in mine Porsche may just reccomend something for liability reasons.

This morning I started my car and it took less than 2 minutes for the car to idle normally, so I'm sticking to that game plan.

LVDell

Hey, at least we are talking about starting the car to take it OUT of the garage. Can you imagine what this thread in the F-Car forum would sound like

Riad

1) Pull off car cover
2) Dust lightly with endangered snow owl feathers
3) Stare admirably for several minutes, turn around then back again quickly to notice any dust the owl feathers missed
4) Have a friend help push the car out of the garage as not to annoy family members with that 8 or 12 cylinder roar
5) Gently open door with kid glove on
6) The car is 4" off the ground, slowly get in to avoid back injury, close door
7) Put on racing gloves
8) Hold steering wheel and gaze out the windshield in admiration
9) Place key in ignition (it's on the right side)
10) Step on clutch, disengage transmission
11) Slowly turn the key
12) Listen closely for wearing timing belt
13) Get out and open engine lid
14) Examine timing belt
15) Write down date/time/mileage to ensure accurate timing belt change
16) Have a friend follow you in his BMW
17) Drive to dealer for maintenance
18) While driving home in your friends bimmer, tell him how stupid his iDrive is.

LVDell

Thanks Rob! I needed a good laugh before my coffee kicked in

...in a nother related note, the wife and I were watching the ALMS 12hrs of Sebring this past weekend as we are watching the starting grid head out and get introduced (type of cars) the wife says as they go through the GT class, "is that a Ferrari F430 in the field?" I pause, look at here, she has a puzzled look, then I ask her, sure why not? and her response is "I thought those cars were garage queens". I almost shat myself from laughing so hard! I should note that my wife is a track junkie herself and really knows her cars (damn I'm lucky) and when she asks the other Docs she works with at the hospital that have F-Cars, she says, "hey, you should come out to the track this weekend, our local PCA chapter is having a DE event". To which they reply, "are you kidding?....these cars are not meant for the kind of 'abuse'...." YOU HAVE TO BE KIDDING ME!!!

RJFabCab

C'mon! Didn't you ?

"START SNOWBLOWER AND IMMEDIATELY START BLOWING SNOW."

I wonder how long it takes the cats to warm up on this Bad Boy...

evo_333

LOL That's a good one...

smackboy1

Interesting. The more I think about this, the more I suspect the reason the manual states to drive off immediately instead of letting your car idle in the garage is for environmental reasons. First thing in the morning the catalytic converters are stone cold so they don't work that efficiently (that and choke = lovely smell of unburnt fuel on startup). So the quicker you drive off, the faster the main cats light up and the less pollution the car emits. Do our cars have pre-cats in addition to main cats?

wross996tt

riad you're hilarious...thanks. This is one of the thoughts as I stated earlier....the environmentalists are quite strong in German manufacturing.

djantlive

Riad, I believe the idle is higher at cold start to warm up the cats. My old RX7 has an accelerated warm up mode which revs the car to 3k upon cold starts for 10 sec or so. A blip of gas takes care of that. Cars definitely run rich at start. That's why short trips are inefficient. Engines run best at operating temp. So, as soon as oil starts to flow, I take off slowly under 3k.

You may have a foul plugs? How often do you drive your car? If it's not daily, try doing that for 3 consecutive days to see if any change in idle when cold.

Riad

I drive my car daily all-year-round. The engine just sounds a bit rough when it starts, nothing out of the ordinary and my 2001 did the same thing.

I don't think its harmful to let the car come to idle, or not, it's whatever everyone's more comfortable doing.

We ALL agree that we keep the RPM's down until the car come up to temp, about 180 degrees.

So we have that going for us, which is nice.

Rob