Idle when netural coasting

Platinumcloud

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i recently i got a new job and i travel 90+ miles round trip. i have to go up and down some hills that are pretty long. so i have been shifting into neutral to save some gas. i know that the standard idle for a d16y7 is 650-700 when all your stuff is off and whatnot. when i coast even with all of my lights and radio off (going 65 mph) my idle stays at about 1000rpms. is this normal?
 

Gunner

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Yes, when your coasting the car can't be at a standstill, you still use the steering wheel and what not which draws power...when you sitting still and nothing at all is running then your idle drops that low.

however In neutral, the engine is at idle speed, meaning the throttle is OPEN. Leaving the tranny in the proper gear according to steepness of the grade means the throttle is CLOSED if your foot is completely off the gas pedal. That saves gas and is also a lot safer when the engine is doing some braking.

if you allow your car to slow you down, you do 2 things, first you are not wasting energy by using your brakes, and when the engine slows you it goes into a super lean mode (usually air fuel ratios above 17:1, sometimes far higher). this does no damage your engine, so don’t worry. However, if you put the car into neutral, the engine must maintain itself so it usually goes into a 14.7:1 air fuel ratio, therefore using more fuel while idling to a stop then [than] while engine breaking.”[braking].

There are many debates wether or not nuetral saves you gas but i find more that lean toward it consuming more. Just my two cents.
 


RonJ

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What is the idle speed when the engine is warm without load? Is it the same when neutral coasting? Spec idle speed for your engine is 670 rpm. Note that your dash tach is very inaccurate in the idle speed range, so hooking up an external tach or scan tool would be needed to gather precise information.

If you leave the transmission in gear going downhill with the car decelerating, you will use zero gas because the ECU goes into fuel cut off mode under these conditions. By neutral coasting, the engine goes into idle mode, which uses gas. So if you wish to save gas, decelerate with your transmission in gear.

With that said, what is your average gas mileage? Probably the best way to improve gas mileage is to do an ignition system tune up - plugs, wires, cap, rotor, ignition timing.
 

Platinumcloud

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im getting 37 miles highway and 32 miles round town. its was rather cold last time i checked. my normal idle speed is about 670. so just to clarify, you use less gas leaving the car in gear and coasting down hills? also i have no power steering or ac engaged when im coasting and my dash tach reads 1000 rpms
 


RonJ

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im getting 37 miles highway and 32 miles round town.
Gas mileage is good -- same for my 97 DX.

its was rather cold last time i checked.
Checked what?

so just to clarify, you use less gas leaving the car in gear and coasting down hills?
Decelerating with the transmission in gear uses ZERO gas until the engine rpms get near idle speed.

my normal idle speed is about 670...also i have no power steering or ac engaged when im coasting and my dash tach reads 1000 rpms
You might want to start by cleaning the throttle body and adjusting the throttle cable to have about 1/2" of slack.
 

billjenkins

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I have read that engine off coasting can harm manual transmissions due to lack of lubrication. 1990 Civic DX. I've been doing it for years occasionally. No problem,but? Any thoughts?
 

XpL0d3r

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12 year old account bumping a 13 year-old thread with a first post. Truly impressed.
 

nd4sped

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12 year old account bumping a 13 year-old thread with a first post. Truly impressed.
Its wild these old accounts coming out of the wood work. Makes me wonder if they are literally 99% compromised logins that are using bot LLM's to produce and test AI.....I hate it.

Or somehow they are able to manipulate registration through an exploit? @Jay Jay Is there an easier way to verify registration date other that what is publicly viewable?
 

nd4sped

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On another note when did RONJ get banned?
 

davidbravo

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Yes, it’s normal for your RPMs to stay around 1000 when coasting at higher speeds, even in neutral. The engine management system adjusts the RPM to keep the engine stable during coasting. Shifting to neutral doesn’t always save much fuel and can affect control.
 


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