Fast idle and "clunk" shifting into reverse or drive. Is this normal?

[kirnma]

In other cars I've owned, the fast idle at startup (engine cold) usually adjusts to a normal idle in 30 seconds, in just enough time to get the oil circulating. However, with the Bronco (2.3L), my fast idle seems pretty high (1300 rpm) and last 3 minutes or longer. If I shift into reverse or drive with the fast idle, there is an audible "clunk" that that comes from the transmission. When the idle is normal (800-900 rpm) it seems fine. I have a couple of questions: 1) Is my high idle normal?, and 2) Should I be concerned about shifting from park to reverse or drive when the fast idle is enabled, or do I just sit it out until the fast idle subsides? The last thing I want to do is screw up my transmission.

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[710-oil-614]

I would definitely say it is best to give your vehicle time to warm up and for the idle to settle in - that being said my FIL starts his Tacoma and within 3 seconds of turning it in already slams it in drive - it is 12 years old and has 175k miles on it and still going strong.

As to how long your bronco is idling, I think that depends on a lot of factors but 3 minutes is excessive.

My 2022 Base 2.3L/10spd would idle high for 30-45 seconds.

My 2023 Maverick 2.0/8spd idles high for about the same amount of time.

 

[PWillette]

I'm about the same...high idle, 1,200rpm and 800rpm low but high only lasts for just about one minute. Three minutes seems excessive. Wonder if high idle duration can be adjusted through Forescan?

 

[kirnma]

I'm about the same...high idle, 1,200rpm and 800rpm low but high only lasts for just about one minute. Three minutes seems excessive. Wonder if high idle duration can be adjusted through Forescan?

Yeah, I was thinking the same thing about Forescan. I'll do some searching on the site about this. Thanks.

 

[Az_Squatch_Bronco]

How cold is the ambient air temperature? On my 2.7 it high idle lasts a minute or 2 in the mornings.

 

[kirnma]

How cold is the ambient air temperature? On my 2.7 it high idle lasts a minute or 2 in the mornings.

True, the fast idle at startup is slightly shorter when the temperature is warmer (e.g. above 60 degrees fahrenheit), but not much. When it's colder (40 degrees or lower), it does go on longer. Heck, even after driving the Bronco and letting it sit (maybe while I go into a store for 10-15 minutes), the fast idle re-engages for up to a minute, and the engine is warm.

 

[BlueWaffle]

Perhaps something is amiss with your coolant temperature sensor.

 

[MileHighCitizen]

My understanding is that oil pressure is achieved within a few seconds of starting the engine, and the high idle speed is to heat up the catalytic convertor so it combusts off any unburned fuel for emissions reasons.

 

[thesocalexplorer]

At ambient temps of 65-70*F in my garage, my bronco high idles for a little over a minute. I've done a few 15*F cold starts when out camping and it high idles for way longer. The 2.3 ecoboost has one of the longest cold-start high idles of all the vehicles I've owned thus far.

 

[kirnma]

At ambient temps of 65-70*F in my garage, my bronco high idles for a little over a minute. I've done a few 15*F cold starts when out camping and it high idles for way longer. The 2.3 ecoboost has one of the longest cold-start high idles of all the vehicles I've owned thus far.

Hmm. OK. Maybe mine is just acting normally. I've had GMs and some Japanese cars and the idle drops in 30 seconds, give or take, every time. I'm not used to this extended high-idle, and it still makes me nervous about shifting into gear. I may be old school on that since today's transmissions and electronics may be able to handle it.

 

[thesocalexplorer]

Hmm. OK. Maybe mine is just acting normally. I've had GMs and some Japanese cars and the idle drops in 30 seconds, give or take, every time. I'm not used to this extended high-idle, and it still makes me nervous about shifting into gear. I may be old school on that since today's transmissions and electronics may be able to handle it.

I hear ya, I've owned a bunch of toyota/lexus products and one nissan 240sx before my bronco, and they all settled down from high idle after 30 seconds too

 

[JL8jeff]

Do you have the defroster or AC on, that might cause it to hold the high idle longer. When mine seems to be holding the high idle longer than I like, I shift it into Neutral and it usually drops down after that.

 

[kirnma]

Do you have the defroster or AC on, that might cause it to hold the high idle longer. When mine seems to be holding the high idle longer than I like, I shift it into Neutral and it usually drops down after that.

No, I turn everything off when I shut the engine down. Again, an old habit as not to overwhelm the battery when I start the car back up. You are correct in that if I shift to neutral the idle sets itself to normal, but I still get that huge clunk when I pass through the reverse gear, including the rear camera coming on for a 1/2 second. I thought there would be a slight pause in transmission engagement to accommodate passing through the gears so I could do just what you described.

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