There has been a lot of confusion/consternation and general head scratching about the use of auxiliary fans and the need for them. I have a 2017 Twin-cooled M8-engined Tri Glide Ultra and decided to put Love Jug Cool-Master auxiliary fans on the engine. Many think that this is a solution looking for a problem. However, mother Harley acknowledges in their own company literature that heat robs engines of power and can affect longevity of their engines.


This brings me to a conundrum experienced recently where the EITMS was kicking in even with the aux fans running and so this morning, with nothing better to do in the dark, I began a search of what is going on. The following was also shared on another website with trike owners.


"Geez fellow trike owners. I report what I find and then you ask me to technically back up what I have found???

Fair request but not one that presents with an easy answer when it comes to the EITMS on the 2017 M8-engined TGU. I signed up this early morning for the H-D Service Information Portal and was unable to buy access for any period of time to H-D service/functional information. There is a limited amount of data that can be gleaned for free. Also went to my 2017 Touring and Trike Model Service Manual and Service Manual Supplement and there was no information to be gleaned about the EITMS.

I am frankly stumped at the moment as to where to get reliable information on how, why and where the EITMS on the new M8-engine Twin-Cooled engine operates. I had read a brief anecdotal report from Kevin at DK Customs where he opined that the EITMS may not be operating on ambient temperatures. However, experientially the other day, when the temps were in the low 70's, the EITMS did not kick in with the Cool-Master fans running. However, when the ambient temperature hit about 80+ degrees with the Cool-Master fans running continuously, the EITMS was kicking on at long lights.

I am frankly as baffled at this point about what controls the EITMS and what conditions trigger its activation? A Google search did not offer the latest information on 2017 EITMS function. Then... I had this light bulb come on and after searching all of these more technical resources, I pulled out the frickin' 2017 Harley-Davidson Owner's Manual for Trike Models. In this very small manual I find the following:

"Operation

When engine temperature reaches a predetermined point, the EITMS turns off the rear cylinder fuel injector. The rear cylinder becomes an air pump which works to cool the engine.

EITMS activate (rear cylinder turns off) when all of the following conditions are met:

Ambient temperature or engine temperature exceeds temperature threshold.

Throttle control is at idle.

Vehicle speed under 1 mph (2km/h).

Engine Speed under 1200 rpm.

Note

EITMS does not activate within the first four minutes after starting the vehicle.

EITMS disables (rear cylinder begins firing again) if any one of the following occurs:

Ambient temperature or engine temperature falls below temperature threshold.

Throttle control is above idle.

Vehicle speed exceeds 2 mph (3km/h).

Engine speed exceed 1350 rpm.

Clutch is released with vehicle in gear.

Engaging reverse.

When the engine is in EITMS operation, you may notice a difference in idle cadence. Additionally, there may be a unique exhaust odor. Both are normal conditions". Information copied from Page 111 of Operation from the Trike Models, 2017 Harley-Davidson Owner's Manual Copyright 2016"


Well, there you have it. The MOCO engineers acknowledge that engine heat is not a good thing despite what anecdotal experiences and/or theories we all come up with. Hope this clears up a little bit of the confusion that seems to swirl around (pun intended) engine temperature management issues. BTW, I am not an engineer and so have to rely on people that know a lot more about these issues than I will ever hope or need to know.

 

While not familiar with the 17 setup, it's my understanding, EITMS is for rider/ passenger comfort, not engine durability. If it were for the engine, you wouldn't be as to disable it.Also,for the 17s, Harley now has a pretty slick setup that replaces the right side midframe air deflector with a deflector/ fan setup that pulls air down and behind the transmission to help with comfort.

 

In Harley's 2017 Owner's Manual, in the section related to the EITMS, it states, "The rear cylinder becomes an air pump which works to cool the engine." It has often been considered a rider comfort feature but apparently in 2017 with the M8 engines at least, Harley is acknowledging that the air pump feature works to cool the engine which in turn can be at least inferred that it will coincidentally improve engine durability.

 

All that to tell us that engine heat is bad...

 

Actually, I went back to the 2009 Tri Glide operator's manual and Harley stated "For those riders who frequently find themselves in riding conditions where the vehicle is subjected to prolonged idle conditions or traffic congestion, the motorcycle is equipped with an Engine Idle Temperature Management System (EITMS) to provide limited cooling of the rear cylinder."


Big Papa in hot AZ, what I am coming to realize after having owned maybe 12+ Harleys is that engine temperature management seems to be becoming more critical as the MOCO increased cubes and has been grappling with cooling strategies. My reason for the thread is that it has been interesting that some of my friends who have large motor Harleys are expressing to me that they think that being concerned about engine temperature management and considering auxiliary fans is like looking for a solution to a non-existent problem which does not seem to be the case.

 

you're making assumptions. eitms has always been promoted for rider comfort. of course it is going to cool the engine. you can't lower the ambient heat without lowering the engine temp....

 

If I may I'd like to put in 2 cents here. I am as far from a technical person as can be possible (Note that our LJ inventor Dave Sandel is a technical genius and he put over 4 years of focused research & development, testing, and common sense into making Love Jugs the extremely effective product that they are. So my answer is not about the science, it's about my customers personal experience. I speak to a ton of customers every day. However they picked it up there is widespread experience that the EITMS is now set to turn off the rear cylinder when the motorcycle is idle and the ambient temperature is I've heard 80, 81, and 82 degrees - so let's call it the low 80s. I am confident that some of this comes from published materials (maybe instruction manuals?) but I'm positive that this is what happens because so many have reported this to me.

Now there can be some confusion because it doesn't happen to everybody. This is because there are two versions out there. I'm not sure how to know which is witch but I can speculate that the older versions didn't have this feature and it was a later "improvement". In any case, that's all I can add - I hope it helps. I imagine that someone will come up with the documentation reference on this but I'm confident that the above is accurate.

 

Are they required for normal riding can't hurt

 

Given an engine's mass, as horsepower(i.e.. heat) is increased, the engine itself acts as a heat sink. Get to a "threshold" power level, and you get a "threshold" heat absorption level. Go past this level? Overheating occurs.
"High" compression is a large contributor to engine heat. Probably one of the biggest.

 

When I got my '13 CVO 110, the first things that I had done (at the 1,000 mile service) was to replace the OEM (catalytic converter exhaust system) with a true dual, no cat system and installing a tuner with a dyna tune.

Later that year I installed a set of the Ward's fans with the thermostatically controlled switch and my bike has never went it the "limp" mode.

When I go to the Tri-Glide (not too far away) I will have the exhaust replaced to eliminate the catalytic converter and will also do the tuner and dyno tune again but unless I have proof that the M8 requires additional cooling assistance I'll wait until I'm sure that it does.

Here in the mid-west the temps here are not as severe as they are in the south and southwest but perhaps in those areas auxiliary cooling is needed and the EITMS activating is an indication that it is.