Curious why "high" RPMs when coasting in neutral?

[RichardCranium]

I am not a flat tow expert either, but the way the mechanic I worked for explained it is that at high rates of speed, the pressure created by the wheels spinning can overwhelm the pump that is spinning slower and can still cause damage.

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[RLmesc]

Where I live it is law that you do not take your vehicle out of a drive mode and "coast" in neutral. There are two reasons why, one - BECAUSE THEY (the law guys) TOLD YOU NOT TO, (and you have no clue why) and TWO, because the people who designed the Maverick, ALSO TOLD YOU NOT TO. 4FKsake, Y will U not listen?.... Sorry I blew up! Nevermind,

 

[Automan21]

I'm not sure if this is the situation, but I know some tunes will increase RPMs to match speed at higher speeds so you don't slam the transmission and damage it putting it back into D. Ford may have programmed that in here for that purpose.

Could be on to something......

 

[MakinDoForNow]

Modern cars shut off all fuel flow when coasting in gear. When you coast in neutral, the [electronic control unit] then has to inject fuel and burn it to keep the engine at idle. When you coast in gear, the momentum of the car keeps the engine spinning rather than the fuel in the tank.

 

[RR - All the way]

Where I live it is law that you do not take your vehicle out of a drive mode and "coast" in neutral. There are two reasons why, one - BECAUSE THEY (the law guys) TOLD YOU NOT TO, (and you have no clue why) and TWO, because the people who designed the Maverick, ALSO TOLD YOU NOT TO. 4FKsake, Y will U not listen?.... Sorry I blew up! Nevermind,

So is Iowa the only state stupid enough to pass a law that cannot be enforced??? Hey, it's my driveway and I will coast if I want. Even if the opinion on this forum is that I am getting lower gas milage for 3/4 of a mile at 800 rpms instead of 12 to 1500 rpms!

Oh, by the way, I love Dubuque and am a Loras grad... Stay Safe!!

 

[RR - All the way]

Modern cars shut off all fuel flow when coasting in gear. When you coast in neutral, the [electronic control unit] then has to inject fuel and burn it to keep the engine at idle. When you coast in gear, the momentum of the car keeps the engine spinning rather than the fuel in the tank.

How do you coast in gear???? The definition of "COAST" as I perceive it precludes having the vehicle in gear. I guess you mean not having your foot on the gas pedal? I guess I am just curious, but at what "spin rate" or rpms does the electronic control unit give the engine gas before you come to a complete stop if you are coasting out of gear?. Sorry, but it really is hard to teach an old dog, new tricks!!!!

 

[RLmesc]

I went to Loras College (grew up in DBQ) as well and the University of Iowa and Crawford University in Atlanta and now, in my advanced age, I teach high performance driver's education for the Porsche Club of America and yes, we are stupid. Wishing to be enlightened, we now wait for your most eloquent illumination of our educational failures. ANDDDDD, Go.... or wait, please, research the WHY, we say what, we said and then reply. If you must, contact the Iowa Hwy patrol office for their input. YOU, of the "Hold my beer AND the watch how many MPGs I can GETS" ilk.... tell us why MPG matters more than SAFETY. I spent 40 years cleaning up after those that drove when they should have been parked. I was an insurance accident reconstructor, my dad was a county sheriff and the mayhem the unknowledgeable left for us to decipher was... well dare I say? INTERTESTING. But, go on, we may have missed something...

 

[Thundercougarfalconbird]

How do you coast in gear???? The definition of "COAST" as I perceive it precludes having the vehicle in gear. I guess you mean not having your foot on the gas pedal? I guess I am just curious, but at what "spin rate" or rpms does the electronic control unit give the engine gas before you come to a complete stop if you are coasting out of gear?. Sorry, but it really is hard to teach an old dog, new tricks!!!!

When you have 8 gears to choose from, there's very little resistance in the top gears. It's basically coasting without having to shift gears, therefore reducing wear on the transmission components. Also means that when braking, the car can shift to an appropriate gear where engine braking can assist and potentially 1) help stop you quicker and 2) reduce brake wear.

Not sure of the RPM range. In my current car, it's anything above 1600rpm for a few seconds after you let off the accelerator, cuts off fuel, then fuel comes back at just above idle (1200rpm) or whenever you touch the accelerator. In 6th gear (manual transmission), you can coast quite a way before cruise control needs to touch the accelerator, then goes right back to coasting.

 

[RR - All the way]

I went to Loras College (grew up in DBQ) as well and the University of Iowa and Crawford University in Atlanta and now, in my advanced age, I teach high performance driver's education for the Porsche Club of America and yes, we are stupid. Wishing to be enlightened, we now wait for your most eloquent illumination of our educational failures. ANDDDDD, Go.... or wait, please, research the WHY, we say what, we said and then reply. If you must, contact the Iowa Hwy patrol office for their input. YOU, of the "Hold my beer AND the watch how many MPGs I can GETS" ilk.... tell us why MPG matters more than SAFETY. I spent 40 years cleaning up after those that drove when they should have been parked. I was an insurance accident reconstructor, my dad was a county sheriff and the mayhem the unknowledgeable left for us to decipher was... well dare I say? INTERTESTING. But, go on, we may have missed something...

Hmm, you do not presume or ASSume much about a person from three or four sentences, do you?? Your failure to recognize sarcasm about the level of Iowa intelligence is really not my problem. The law as described by you is unenforceable. Does that mean I flaunt it. No. I taught defensive driving for about 25 years but to just people without a Porsche. Seems like it should be similar??

I was at Loras from 1962 through 1966. When did you attend. Peace!

 

[MakinDoForNow]

How do you coast in gear???? The definition of "COAST" as I perceive it precludes having the vehicle in gear. I guess you mean not having your foot on the gas pedal? I guess I am just curious, but at what "spin rate" or rpms does the electronic control unit give the engine gas before you come to a complete stop if you are coasting out of gear?. Sorry, but it really is hard to teach an old dog, new tricks!!!!

Coast in gear is no foot on gas ice still turns all ecu needs to do is inject fuel to turn power on. If coasting in neutral ice burning fuel at whatever rpm ECU determines is necessary if you want to put in drive. I do not know how the auto trans acts differently in the coasting in different drive modes, presumably will be more economic in eco than in standard drive. I have only put 500 miles on my Tremor and haven't paid attention if it costs further from 50-0 in eco than std.

 

[RLmesc]

Hmm, you do not presume or ASSume much about a person from three or four sentences, do you?? Your failure to recognize sarcasm about the level of Iowa intelligence is really not my problem. The law as described by you is unenforceable. Does that mean I flaunt it. No. I taught defensive driving for about 25 years but to just people without a Porsche. Seems like it should be similar??

I was at Loras from 1962 through 1966. When did you attend. Peace!

Ohh I got the sarcasm and I like poking back as well. I went to LC from ‘71-‘73, then UofI ‘74-‘78. I delivered newspapers to the campus at LC from ‘65-‘70, we may have crossed paths. My dad was a County sheriff back then. Did he cross your path as well? People didn’t obsess about mpg back when it cost $0.25 a gallon. LOL

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