14 Limited EITMS changes
I just took a 10 min ride down the road it is 83 dg out and it was dropping the rear cyl at the first light I was at my 09 flhx would be as hot as a waffle iron before it would drop the rear cylinder
Road Master
Joined: Dec 2010
Posts: 1,248
Likes: 1
From: Jacksonville, NC
What exactly is the perception of the rider when the EITMS activates and shuts down the real cylinder? I'm just curious because I have a softail which has to have the system dealer activated and I've never had it turned on. Does it sound like it's idling funny?
Tourer
Joined: Jan 2013
Posts: 354
Likes: 88
From: British Columbia, Canada
Oh, and let's get this straight. EITMS only activates when you come to a complete stop. Some guys make it sound like you can activate it while you're moving.
Tourer
Joined: Dec 2010
Posts: 250
Likes: 0
From: Mesa arizona
EITMS does not help cool the motor and when it activates it does not mean the motor is overheating, it is a strategy that is in place to try to slow down the rate that engine temp increases. On an air cooled motor running stationary, the longer it runs the hotter it's going to get. It is set at a lower activation temp on the 2014. I keep it turned on all the time on my 2014 Ultra Limited and yes it does come on at every light right now in town just like my 2009 Street Glide did when outside temps were above 80 degrees and humid. However when sitting at the light I can also reach out to the side of the lowers and feel the radiators doing their job as well. I do not feel any engine heat radiating up to me as I did with the 2009 Street Glide. Very pleased with the water cooled system so far.
Tourer
Joined: Mar 2010
Posts: 430
Likes: 2
From: Dirty City
I'll explain it further for you: It takes x amount of energy to take the engine through two full rotations at idle. Normally that energy is being provided by two cylinders, so each cylinder is providing x/2. Now shut down one cylinder. Now you have a requirement of x, but a cylinder only providing x/2. Obviously if all active cylinders combined (at this point only 1) are only providing half of the necessary energy to idle, your RPMs will drop and the engine will stall. So to compensate the front cylinder has to burn more fuel to take up the slack left by the deactivation of the rear cylinder. These are, of course, approximations since the thermal efficiency of a single cylinder is a bit higher than that of two. Remember also that the rear cylinder is still creating drag through pumping losses, since the valves still operate, so it's not an air spring but rather a load.
When more fuel is burned than is necessary to overcome the current load, you have an increase in RPMs. When less fuel is burned than is necessary to overcome the current load, you have a decrease in RPMs. Since the load doesn't change when you go into EITMS, the usable energy taken from the fuel burned must necessarily remain the same as well.
It's science.
The same amount of heat (from combustion) cannot be coming off the engine from one cylinder. Thus... it's not generating the same amount of heat and that is a loose translation for "running cooler" than if the engine was on two cylinders. Blah, Blah, Blah right? It's still killer hot.
Now will the engine be 50% cooler? No, because each cylinder generates more heat than it's fins can dissipate at stand still. Which is where everyone is pointing out that all the EITMS does is decrease the Rate in which the engine overheats.
Last edited by Ovaltine Jenkins; Sep 4, 2013 at 03:30 PM.
Tourer
Joined: Mar 2010
Posts: 427
Likes: 1
From: Hot Springs, AR
It seems odd that the sequence of operation would bring on the EITMS before attempting to control the temps with the radiator fans as the first step. And a control strategy that activates the EITMS at 80 regardless of actual head or coolant temp seems wrong too. I bet there's more to this story eventually.
Seasoned HDF Member
Joined: Jan 2006
Posts: 11,455
Likes: 2,985
From: Charleston, SC
Actually, yes, it does get more fuel and air. There is no "amount of spark" you either have it or you don't. The need for more fuel and air is because the revolutions are staying the same and the one cylinder is doing the work that two cylinders were doing.
I'll explain it further for you: It takes x amount of energy to take the engine through two full rotations at idle. Normally that energy is being provided by two cylinders, so each cylinder is providing x/2. Now shut down one cylinder. Now you have a requirement of x, but a cylinder only providing x/2. Obviously if all active cylinders combined (at this point only 1) are only providing half of the necessary energy to idle, your RPMs will drop and the engine will stall. So to compensate the front cylinder has to burn more fuel to take up the slack left by the deactivation of the rear cylinder. These are, of course, approximations since the thermal efficiency of a single cylinder is a bit higher than that of two. Remember also that the rear cylinder is still creating drag through pumping losses, since the valves still operate, so it's not an air spring but rather a load.
When more fuel is burned than is necessary to overcome the current load, you have an increase in RPMs. When less fuel is burned than is necessary to overcome the current load, you have a decrease in RPMs. Since the load doesn't change when you go into EITMS, the usable energy taken from the fuel burned must necessarily remain the same as well.
It's science.
Sure it can. If a cylinder burns twice as much fuel at the same fuel:air ratio and with the same thermal efficiency, twice as much heat will be generated.
Again, it decreases the rate at which the rear cylinder overheats, not the engine as a whole. The same work is being done, so the same fuel is being burned. If you want, I can explain the interactions between force, work, and energy to help clarify.
I'll explain it further for you: It takes x amount of energy to take the engine through two full rotations at idle. Normally that energy is being provided by two cylinders, so each cylinder is providing x/2. Now shut down one cylinder. Now you have a requirement of x, but a cylinder only providing x/2. Obviously if all active cylinders combined (at this point only 1) are only providing half of the necessary energy to idle, your RPMs will drop and the engine will stall. So to compensate the front cylinder has to burn more fuel to take up the slack left by the deactivation of the rear cylinder. These are, of course, approximations since the thermal efficiency of a single cylinder is a bit higher than that of two. Remember also that the rear cylinder is still creating drag through pumping losses, since the valves still operate, so it's not an air spring but rather a load.
When more fuel is burned than is necessary to overcome the current load, you have an increase in RPMs. When less fuel is burned than is necessary to overcome the current load, you have a decrease in RPMs. Since the load doesn't change when you go into EITMS, the usable energy taken from the fuel burned must necessarily remain the same as well.
It's science.
Sure it can. If a cylinder burns twice as much fuel at the same fuel:air ratio and with the same thermal efficiency, twice as much heat will be generated.
Again, it decreases the rate at which the rear cylinder overheats, not the engine as a whole. The same work is being done, so the same fuel is being burned. If you want, I can explain the interactions between force, work, and energy to help clarify.
If you looked at the fuel tables you'd see that the front cylinder is not getting twice the fuel. It's getting more air.
Simply put, at idle the engine increases the efficiency (output) of the front cylinder by allowing it more air.
lp
Last edited by lp; May 6, 2015 at 01:49 PM.
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
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From: Phoenix '53, '88, '09 Big Twins
the air moving through the cylinder removes heat
mike
Club Member
Joined: Jan 2011
Posts: 937
Likes: 22
From: Ontario, Canada
Actually Harley marketed it as a way to help "Cool" the motor as well for rider comfort. You can find that in the marketing info like below.
"During hot idle, or when the motorcycle is off-throttle and running at hot temperatures, EITMS shuts off fuel to the engine’s rear cylinder, leaving it to idle on the front cylinder only. Without combustion, the rear cylinder and exhaust header will begin to cool, bringing relief to the rider (and passenger) soon after. Once the rear cylinder cools to a predetermined temperature, or as soon as the rider accelerates, both cylinders resume operation. And by maintaining constant rpm during rear cylinder “shutdown,” transitions between one and two cylinder operation are nearly seamless.
EITMS is purely for rider comfort. When it activates and “shuts off” the rear cylinder, it’s not because the motor is overheating. It’s designed to reduce the heat radiating from the rear cylinder to the rider."
http://www.harley-davidson.com/en_US...conditions.pdf
lp
"During hot idle, or when the motorcycle is off-throttle and running at hot temperatures, EITMS shuts off fuel to the engine’s rear cylinder, leaving it to idle on the front cylinder only. Without combustion, the rear cylinder and exhaust header will begin to cool, bringing relief to the rider (and passenger) soon after. Once the rear cylinder cools to a predetermined temperature, or as soon as the rider accelerates, both cylinders resume operation. And by maintaining constant rpm during rear cylinder “shutdown,” transitions between one and two cylinder operation are nearly seamless.
EITMS is purely for rider comfort. When it activates and “shuts off” the rear cylinder, it’s not because the motor is overheating. It’s designed to reduce the heat radiating from the rear cylinder to the rider."
http://www.harley-davidson.com/en_US...conditions.pdf
lp
