First, I’m on old guy. Old school…….was always told not to high rev the engine when starting a cold engine, even in summer. Oil needs to circulate from the sump.

1st start of the day, RPM’s jump immediately to 1700-1800 and stay there for 15-20 seconds. Always. Then drop to 750 or so. Subsequent starts vary throughout the day. Haven’t had the car in cold temps yet, so that will be interesting. Or irritating…..

I couldn’t find any forum discussion but coincidentally saw a syndicated newspaper article a couple days ago that said don’t do that on any engine. It doesn’t help me that maybe all newer cars with high-dollar oil do the same, it’s against my nature, but I don’t control start-up.

Both my wife and I cringe and we don’t shift until RPM’s drop.

Off my soapbox……

 

At the risk of sounding like a Land Rover dealer, they all do that - at least on an initial start. Not temperature dependent either, if the engine isn’t warmed up when starting it will rev a little higher just as yours does.

 

The idle increase command upon cold start is pretty simply to warm the cats / oxygen sensors / etc .... with the sole purpose of getting emissions sorted out quickly. I believe in the past, most emissions came from cold motors. Not bad for the motor or bearings I don't think... pretty standard in new cars. I think if you stomped on it to 4000 RPM's, when cold, yes that would be bad.

 

Yep they all do that for all the reasons mentioned. There is a section in the manual specifically about this. With all that said I am with you on waiting to shift. I always make sure it finishes the cycle and the rpm’s drop before I put mine in gear.

 

well, sure enough……

 

My D250 doesn't do this, the RPM rise slightly on cold start but only to around 1,000rpm

l assume this is because it's a diesel? But l remember years ago all my old cars would sit at 1500rpm or more when cold until you pushed the "choke" control in, and it took a lot longer than 30 seconds before the vehicle would run without the "choke"

And this was back in the 1980's when engines weren't as forgiving of abuse as they are now.

 

Nope, gas.

I’ve had engines that start low but then slowly rise when cold. This is different. But, I’m over it, moving on to my next gripe…..🤔

 

If it's any consolation my GLS450 does the same thing. Winds up and hangs there for a long time until it warms enough for what I believe are the wastegates closing. After that closes the exhaust gets quiet and the idle goes down to 700.
You're doing the right thing by waiting for the idle to lower. Not great to just take off with the idle that high.

 

I would agree with that advice about waiting to take off. I also wait until the idle comes down, as I wouldn’t want to slap into drive at high idle. But if I recall, one time I was in a rush and selected Drive and there was a slight delay, as the engine electronics took charge and first brought the RPMs down before the tranny engaged. Just like smart phones, these are smart cars and are constantly thinking for you. That’s why when you try to reverse with the drivers door open, it shifts into park, as frustrating as that is. Yes, it’s a bit of a nanny state for drivers but you can find plenty of videos on YouTube of people chasing their car down their driveway when they stepped out while in gear. Stupid people+Smart car at least saves a few lives a year.

 

I don’t believe I’m a candidate for the Darwin Awards, but, as they say, I have had moments if brains were taxed I’m due a rebate…..🫣