Do I need to wait for idle to drop before driving?

[MDH]

My understanding is that modern cars don’t need to wait for the idle to drop before driving. If that’s true, does anyone really know why the idle revs higher on the Broncos for the first two or three minutes or so and then drops? Maybe I’m old school; I just feel it’s safer to wait for it to drop.

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[Feral1]

Normal for 3 reasons. Cold oil is more viscous and needs to circulate, warms up internals to reduce wear, faster operating temps reduce emissions as the ECU leans out your air/fuel ratios.

 

[SwiftMountain]

This is just anecdotal but I always wait for it to idle down as well. The few times I have been in a hurry and not waited I feel like the shift into drive is a little more rough.

 

[TXBronco1313]

I personally let it idle until it drops below 1. I think not doing it won’t break the vehicle but I like to treat mine well

 

[Area51BS]

I just drive off gently. Tranny is noisy when cold anyways and prefer not to hear that under load. CarPlay not connecting helps since I sometimes wait for that to connect. Imaging how much gas would be saved not waiting on CarPlay!

 

[The Pope]

Short answer: You don't have to wait.

Long Answer: You don't have to wait, as the ECM is Only looking at the Upstream O2 Sensor(s) for the A/F Ratio. The Downstream O2 Sensor(s) is also going through the Warming Up Process. Once the Downstream O2 is up to temperature, the ECM will start looking at it, along with the Upstream O2 for A/F adjustments. also at the same time, the ECM will allow the idle to lower to it's normal RPM.

 

[CarGuy]

You don’t have to wait. I wait for it to drop in the winter on cold days. In summer I start it and drive. In all cases, I wait for the engine/trans to warm up before any “spirited” driving (high rpm, etc.).

 

[battering ram]

I’ve never waited for anything. Just get in and drive

I’ve had multiple cars go over 200,000 miles and went further after I sold them

what I find funny. Is guys who baby their car to last forever. Eat fast food and drink a case of soda weekly. They care more about their car lasting for ever vs themselves!!

 

[bassist]

It’s fine - you just need to be sure to rev the engine hard when shifting into reverse or gear.

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Don’t do this

 

[JL8jeff]

With my 2.7, I put it into neutral shortly after starting it and it will usually drop down to 800 rpm's much quicker. I hate the high rpm startup on the modern cars but I assume it's to warm up the cats faster to lower emissions.

 

[bassist]

With my 2.7, I put it into neutral shortly after starting it and it will usually drop down to 800 rpm's much quicker. I hate the high rpm startup on the modern cars but I assume it's to warm up the cats faster to lower emissions.

Have you used a manual choke (or enrichment) before?

They also cause RPMs to rise.

Depending on the air temp, you may have to leave the choke out for just a split second or potentially for a few minutes.

With my mower, generally it’s out only long enough for it to crank. With snowblowers, it’s a bit longer.

On an air cooled motorcycle, like older Harleys, you might even leave the enrichment running until the cylinder head feels warm.

 

[UncleBrad]

It’s fine - you just need to be sure to rev the engine hard when shifting into reverse or gear.

Spoiler

Don’t do this

Yes! 7000 RPM should do it.

 

[Mako]

My understanding is that modern cars don’t need to wait for the idle to drop before driving. If that’s true, does anyone really know why the idle revs higher on the Broncos for the first two or three minutes or so and then drops? Maybe I’m old school; I just feel it’s safer to wait for it to drop.

Drive it like you stole it!

 

[JL8jeff]

Have you used a manual choke (or enrichment) before?

They also cause RPMs to rise.

Depending on the air temp, you may have to leave the choke out for just a split second or potentially for a few minutes.

With my mower, generally it’s out only long enough for it to crank. With snowblowers, it’s a bit longer.

On an air cooled motorcycle, like older Harleys, you might even leave the enrichment running until the cylinder head feels warm.

Yes, I've had plenty of older cars with manual chokes and spring activated chokes. Outboard motors are the hardest to start and keep running for the first minute. But computer controlled cars can keep the engine running without the high rpm so it's mainly for heating up the cats and emissions.

 

[65CarryAll]

Excessive idling at start up to "warm it up" is not doing anything good for your engine, it actually causes more wear. If you really want your vehicle to last longer you'll be best to follow manufacture recomendations and start driving gently within the first minute or so. Vehicles warm quicker while driving.

I also found my 2.7 idle rpm at cold start will usually drop down if I shift to neutral for a few seconds prior to hitting drive or reverse. Doing this will soften the transmission engagement.

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