Couldn't find this on the forum.

After a cold start, do you wait for the "noisy" idle to settle before driving off or do you drive off straight away?

 

What makes it idle like that anyway?

 

Question also is "why". With my other cars the automatic choke makes the idle revs higher but with Porsche is seems more noisy than high

 

I think partially depends on how long the car has been sitting. One time I hadn't started my 996 Turbo for about 6 weeks (in winter) and awful clatter for half a minute or so until the oil got recirculated through the engine. Oil will drain downward if car sits too long.

I always give my cars at least a few seconds after starting before I drive off.

 

Why does it rattle on start up? All Boxer engine configurations do (my BMW twin motorcycles do it as well). The cylinders are laying in a horizontal plane and the oil has to pump up to the lifters. Once it does, the value train quiets down as it has some lubrication. Its also very common for all boxers engines to emit a puff of smoke on startup from oil pooling in the cylinders.

Now, want to have some fun? When do you think you engine is warmed up enough to give it a full power run? Most people will say its warmed up with the coolant gauge is in the middle. but its really not warmed up until the oil temperature is up to normal. You can see both in your instruments, and you will see also that your oil temp is still not up to temp until about 8 to 10 minutes after engine start.

 

I thought it had something to do with exhaust valves opening up on cold starts.

I'm not asking when you should start driving hard. I know you have to wait for the oil temp/pressure to be up for this.

My question remains do you drive off casually straightaway or wait for it to quieten.

 

Porsche says drive it immediately. If you do it will settle into normal idle pretty fast. Just don't hotfoot it til the oil is warm- per drcollie above.

Mine doesn't really "clatter" on start up, just sounds like me waking up. I think it may have something to do with the high pressure direct injection mechanism....

 

I don't have any noisy idle. I let the engine run until the oil and water temps have risen a bit before driving away. I warm up the engine because I hit high RPMs as soon as I exit my neighborhood and turn unto the public roads. I don't feel comfortable driving that aggressively with a cold engine.

 

The cold start has nothing to do with boxer engines per se. Macan V6 engines do it to. PAG is doing everything it can do get the lowest possible emissions. One thing is to get cats hot as fast as possible. Its more than just opening valves, and its not specific to flat 6 engines.

Its all about EU emissions. Yes, drive aways ... put it in sport + . Do not exceed 4K until your oil is above 175. Then you are golden.

 

I always wait for the idle to level off/drop before driving off... I thought that was advised in the manual somewhere but perhaps I made that up. I do also wait (best as possible) for the oil to warm to normal temps before giving it hell.

 

SAI, secondary air injection, injects air into exhaust ports to heat up the cats faster. This typically coincides with the higher idle RPM and the louder exhaust. You'll hear it when it shuts off.

I used to wait for this to shut off, but its about 90 seconds, and there is no point to idling for that long, so I typically give it about 20 seconds and then drive off.

 

Hmm, mine is definitely not 90 seconds... I'd say on a normal fall day it is 30-45 seconds or so. It is a bit longer during really cold days in mid-winter though.

 

The Mezger engines sound like someone is inside smashing the engine with a hammer on start up. The 9A1 doesn't have clatter as far as I've heard in my car.

I would drive the car immediately after the cold start. These engines are designed to get rolling on start up. I just don't go above 2000 RPM until the coolant is up to temp. The oil viscosity is essentially (not exactly) the same at 100F and 200F. So oil temps don't matter much.

In my GT3 I have to additionally wait for the transmission oil to warm up before pushing the car - 15 minutes.

 

By the time I settle in and buckle up, the idle has usually returned to normal. Like others, I don't get on the car hard until the engine has warmed up a bit.

 

Like others, I wait for the initial idle to settle down, then drive calmly until all temps are up to normal.