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Discussion Starter #1
I did a search of threads, but I could not find anything related to how much fuel consumption for the FJ at idle (I'm geeting old, and my computer skills seem to be getting less by the year). I was hoping someone has some experience in this area. Was looking for a baseline with nothing running, then also with the A/C running. Let me know if you have any experience or could point to a thread with this discussion. Thanks.
 

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0 mpg would be my guess. :lol:

I know we had a discussion on this once and we came to the conclusion that an FJ could idle for well over 24 hours from a full tank of gas. Of course this would not be good for the engine. But it would do it.
 

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@ 700 rpm with a hot engine, it ranges from about 1.4L to 2.0L per hour

Don't remember with the AC on...
 

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In a survival situation - eg stuck in a blizzard - knowing the fuel consumption rate would be a life saver

True a dead idle would be very bad for the motor.

Companies like Kussmaul make Idle Up boxes for diesel and gas motor engines from Ford and GM. Primary application is ambulance or fire where the vehicle is powering emergency lights for long periods.

The batteries would go dead if at flat idle, but at 1,200 RPM the alternator can keep up
 

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Discussion Starter #5
In a survival situation - eg stuck in a blizzard - knowing the fuel consumption rate would be a life saver

True a dead idle would be very bad for the motor.

Companies like Kussmaul make Idle Up boxes for diesel and gas motor engines from Ford and GM. Primary application is ambulance or fire where the vehicle is powering emergency lights for long periods.

The batteries would go dead if at flat idle, but at 1,200 RPM the alternator can keep up

Why is it bad to idle for a long period of time at a lower RPM?
 

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Why is it bad to idle for a long period of time at a lower RPM?
Good or bad, I don't know. However I always notice that police cars in me town rarely turns off the engine. I can understand K-9 squad car with a police dog, poor dog would roast on a hot summer day. I don't understand when they go to lunch and let the car idle for 45 minutes while the sit in the restaurant and have lunch.
 

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Why is it bad to idle for a long period of time at a lower RPM?
With emergency equipment, running all those accessories (Emergency lights, other equipment, etc) the alternator is putting out a fraction of its output at dead idle. Doesn't take long for the battery to go dead

Kussmaul Electronics Co., Inc. Auto Throttle 1 Data Sheet

A lot of heavy duty equipment, including 1 ton and 3/4 ton pickups also come with this feature from the factory

A dead idle cold will cause incomplete combustion, loading the crankcase with unburned fuel. This is a huge problem with diesel engines with DPF's. With gas motors, spark plugs will foul

A dead idle in very hot conditions will cause overheat problems as the water pump isn't running fast enough to effectively cool. With most thermostatically controlled cooling fans, using a hydraulic hub clutch like our FJ's, the fan isn't turning fast enough to be effective either, especially with A/C on

An electric cooling fan is much more effective while stationary, as it runs at full speed. However, it has large amp draw, and a dead idle results in the dead battery problem again

Most medium duty and almost all heavy duty equipment use cooling fans run by compressed air, which the vehicle will use for the brakes anyway. This sort of cooling fan also runs at full speed at idle.
 

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Discussion Starter #8
With emergency equipment, running all those accessories (Emergency lights, other equipment, etc) the alternator is putting out a fraction of its output at dead idle. Doesn't take long for the battery to go dead

Kussmaul Electronics Co., Inc. Auto Throttle 1 Data Sheet

A lot of heavy duty equipment, including 1 ton and 3/4 ton pickups also come with this feature from the factory

A dead idle cold will cause incomplete combustion, loading the crankcase with unburned fuel. This is a huge problem with diesel engines with DPF's. With gas motors, spark plugs will foul

A dead idle in very hot conditions will cause overheat problems as the water pump isn't running fast enough to effectively cool. With most thermostatically controlled cooling fans, using a hydraulic hub clutch like our FJ's, the fan isn't turning fast enough to be effective either, especially with A/C on

An electric cooling fan is much more effective while stationary, as it runs at full speed. However, it has large amp draw, and a dead idle results in the dead battery problem again

Most medium duty and almost all heavy duty equipment use cooling fans run by compressed air, which the vehicle will use for the brakes anyway. This sort of cooling fan also runs at full speed at idle.
Thanks for the information. I do not think I will be idling for long periods of time unless in an emergency situation. Do you have any idea what it might cost to do the upgrade like the emergency equipment vehicles? I could see it being usefull in quite a number if different situations.
 

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Do you have any idea what it might cost to do the upgrade like the emergency equipment vehicles?
Around 8 years ago when I was a volunteer firefighter it cost us around $900 parts and labor to install an up idle system from Kussmaul into a one ton pickup

Most HD and MD chassis now offer an up idle switch as standard or factory option. Even the new diesel 3/4 and 1 ton pickup trucks from Ford, Dodge, and Chevy offer it

IIRC the Kussmaul can use engine vacuum to pull on the throttle cable. There is the catch, there is no throttle cable in the FJ

Not sure how one would achieve up idle in an FJ, unless one fiddled around with the pedal itself
 

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I have no details besides operational experience.

I've idled the engine with the heat on during a very cold night more than once. I know that I burned fuel, but the amount was insignificant. Heat and A/C are different draws on the electrical system - but I haven't had problems doing it.
 

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Its nice. If you just pull it out, you can raise the idle to about 1500RPM. However, you can also press the gas pedal down as far as you want to raise the rpm higher, then pull out the lever, and then it holds that rpm. Kind of a poor mans cruise control on vehicles lacking cruise control as well. It also works great for when you are winching to keep the the batteries more charged.
 

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ok, that's it... i know this is a very old post... but i just have to say it.

I have an FJ sitting right out side... of which i know every square inch of it's build... and i'd like to make a few things very clear...

*the FJ doesn't have a throttle cable* - actually... yes it does, it's quite apparent right on the side of the throttle along with the idle air control and cruise control.

*the manual FJ doesn't have linkage and is fully electronic past the shifter* - pretty sure that's dog leg links going from the bottum of the shifter assembly going to the top of the transmission...

*the manual FJ transfercase is still electronic like the auto* - ... -sigh- no it's not... it's linkage controled and does not use the outrageously expensive electronic actuator that likes to stick in the auto version.



again, sorry for bringing up such an old post. but i'm tired of seeing people put stuff on here like they know something when they don't. if you don't know, don't say anything...

i will go back to my cave now.
 

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*the FJ doesn't have a throttle cable* - actually... yes it does, it's quite apparent right on the side of the throttle along with the idle air control and cruise control.
No it does not

I have attached the appropriate sections of the shop manual.

A lot of folks also don't believe the FJ has electric assist power brakes. Yes it does
 

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