High Transmission Temperature

[plus 3 golfer]

I find the grade assist doesesnt work that well. Often times it wont do anything whatsoever when traveling down an extremely steep hill, and it will run the engine at nearly redline when traveling down a shallower hill. I think it's programed poorly. Both of our CMAXes do it.

Grade assist doesn't "run" the engine.   It allows the engine to spin (no fuel) to regulate speed when sufficient regenerative braking is not available. Grade assist will not slow you down. The engine may rev very high it the HVB is "full" (sufficient regenerative braking not available).  IMO grade assist is not programmed "poorly."

 

When I travel in the mountains of AZ, it maintains speeds very well going down grades whether steep or moderate.  If you are familiar with US 60 between Superior and Show Low, there are significant grades especially the descent to the Salt River from both directions.  I can use a combination of grade assist, Low gear, and neutral to regulate speed and virtually never have to apply the friction brakes.  So, going into a hairpin curve with a speed limit of say 15 miles per hour and one is doing 50 mph using grade assist to hold speed, I shift to low to allow the engine to reduce speed.  Assuming no traffic, I am able to time the slow down without using friction brakes,  Coming out of the turn, I can shift to neutral to pick up speed and then back to drive to allow grade assist to again maintain speed. IMO, grade assist does what is quoted in Bill-N post very well.

[hybridbear]

I discovered something interesting regarding the TFT pump in the Workshop Manual yesterday.

• This transmission has one simple planetary gear set. The planetary gear set is used to match the vehicle speed to the desired engine speed for maximum efficiency.
• The ring gear is connected to the transmission final drive though the middle gear on the transfer shaft. The ring gear rotates when the vehicle is moving.
• The planetary carrier is splined to the transmission input shaft and is connected to the engine. The carrier rotates with the engine crankshaft. The planetary carrier is also used to drive the hydraulic fluid pump.
• The sun gear is splined to the generator/starter.

[obob]

I discovered something interesting regarding the TFT pump in the Workshop Manual yesterday.

 

So I think this might be saying that when the engine is used to slow down the car, the transmission is being cooled.  Is that how you see it ?  I assume this would be for the hybrid.  

[plus 3 golfer]

Any time the engine turns the internal TF pump runs.  During regenerative braking ICE is not turning and TFT rises quickly in the Hybrid due to the heat generated by MG1 motor losses.  You can see the rise just in normal braking.  The hybrid and Energi have the same transmission except for the final drive and the external electric TF auxiliary pump on the Energi.

 

So, how much might the TF rise in temperature when ICE is not turning?  If one assume 90% efficiency of MG1 and say 0.4 kWh of regeneration during normal braking (or going down hill) to the HVB, MG2 heat losses are 0.044 kWh or 44 Wh.  Assume the TF has a specific heat value of 0.44 BTU/Pound^oF and assume the 5.71 quarts of TF weighs about 10 pounds.  Then, (3412 BTU / kWh) * (0.044 kWh) / (0.44 BTU/Pound) / 10 pounds = ^oF (Change in Temperature) =  34.12 ^oF .  There will be some dissipation of heat during the time of regenerative braking so TFT likely won't rise 34 ^oF, but one can see that TFT can rise considerably due to regenerative braking.  

 

Now assume the Energi is going down a step hill and regenerates 10 times the Hybrid example (obviously over a longer time period), Even though there would be some heat dissipation over the longer time period, one can see why the Energi needs an auxiliary electric TF pump. There's a lot of heat losses to dissipate and TFT likely would rise too high without the auxiliary pump.

 

The same logic would apply to MG1. (I think my math is OK) :)

 

Edit:  inadvertently reversed MG1 and MG2.  MG1 is the generator and MG2 is the traction motor used during regenerative braking.

Edited August 20, 2015 by Plus 3 Golfer

[obob]

I couple weeks ago I took a 250 x 2 mile trip.  Very hilly for half of it.  On the way out I used Forscan.  To the best of my memory, and it is not that great - I should have just wrote the numbers down, the trans temperature was mostly around 148 and went up to 152 on a big long hill. (as I recall the radiator temp was around 183.) 

Edited August 29, 2015 by obob

[hybridbear]

So I think this might be saying that when the engine is used to slow down the car, the transmission is being cooled.  Is that how you see it ?  I assume this would be for the hybrid.  

Correct. The planetary carrier is connected to the ICE. Anytime the ICE turns the planetary carrier turns.

 

Any time the engine turns the internal TF pump runs.  During regenerative braking ICE is not turning and TFT rises quickly in the Hybrid due to the heat generated by MG1 motor losses.  You can see the rise just in normal braking.  The hybrid and Energi have the same transmission except for the final drive and the external electric TF auxiliary pump on the Energi.

What kind of rise do you see in the hybrid during regen braking? Does the TFT rise every time you brake & stop with the ICE off? Most of the rise I observe in the Energi is when driving freeway speeds in EV mode. I will need to log some more data, though. Are you able to log your TFT using Torque Pro? I think I'll log MPH & TFT in the Energi. Any other PIDs that would relate to TFT temp that I should track?

[ptjones]

I watch my TFT pretty close and it doesn't change very quickly up or down. WT is a different story, it changes very quickly. ;)

 

Paul

[plus 3 golfer]

What kind of rise do you see in the hybrid during regen braking? Does the TFT rise every time you brake & stop with the ICE off? Most of the rise I observe in the Energi is when driving freeway speeds in EV mode. I will need to log some more data, though. Are you able to log your TFT using Torque Pro? I think I'll log MPH & TFT in the Energi. Any other PIDs that would relate to TFT temp that I should track?

I reported some observations in March in a post of testing I did  (my example above was illustrative not what I ever observed).  When I applied the brakes to increase regen braking, ICE is off and motor coil temperature began to increase immediately up about 10+ F at stop depending on initial speed (more heat losses to dissipate coming to a stop from higher speed).  TFT lagged coil temperature rise by several seconds and increased maybe up to 7 F.  IIRC, ECT increased also likely because there would be less air flow through the radiator when slowing and the heat still stored in ICE was being dissipated.  

 

Knowing what I know now about grille shutter operations , the shutters in my testing were likely opening more as speed was decreasing to allow more air flow to maintain ECT and limit its rise.   

 

I don't use Torque Pro any more.  I use FORScan.  When (if) FORScan allows recording PIDs from more than one module at a time, we can get a better picture of what is happening under normal operating conditions (no grille covers).  I don't know the PIDs to input into Torque Pro for grille shutter operation (and perhaps other relevant data),

Edited August 20, 2015 by Plus 3 Golfer

[ptjones]

On the FWY when ICE stops I believe coolant heats up at the top of ICE because of lack of circulation and the cylinder heads are the hottest part. I see about a 2*F increase in WT, after about 30 seconds temps start going down with a usual drop of 4-15*F depending how long you are in EV Mode.  Also temps go down a few degrees when the ICE starts because of circulating cooler coolant with hotter at the top of ICE. Changes in TFT are very slow, on FWY around one degree per minute with temps going up. :) 

 

Paul  

[hybridbear]

I reported some observations in March in a post of testing I did  (my example above was illustrative not what I ever observed).  When I applied the brakes to increase regen braking, ICE is off and motor coil temperature began to increase immediately up about 10+ F at stop depending on initial speed (more heat losses to dissipate coming to a stop from higher speed).  TFT lagged coil temperature rise by several seconds and increased maybe up to 7 F.  IIRC, ECT increased also likely because there would be less air flow through the radiator when slowing and the heat still stored in ICE was being dissipated.  

 

Knowing what I know now about grille shutter operations , the shutters in my testing were likely opening more as speed was decreasing to allow more air flow to maintain ECT and limit its rise.

The grille shutters will open when the ICE temp exceeds 210-215 F. This can happen when stopped or even when driving at freeway speeds in EV mode. I believe this is because the hot coolant naturally floats to the top & the sensor is at the top.

 

I recorded TFT on a ~13 mile trip last night. Most of the drive is on the freeway at speeds of 55-60. The TFT rose slowly in city driving before reaching the freeway. The TFT rose at a pretty steady pace while driving on the freeway. A couple times I had to brake for cloverleaf ramps. There was a decrease in the slope of the TFT increase with the regen & acceleration. Once I exited the freeway and drove the last 1.5 miles on city streets to home the TFT stayed steady at 103 F and then began to fall, stopping at 101 F when arriving home. The TFT started at 72 F and the ambient temp was in the low 60s with rain.

[ptjones]

Another note is that TFT goes down with OT, pretty much a direct correlation, one for one degree OT. :) 

 

Paul 

[SPL Tech]

I In my suburban and urban driving, there are a lot of hills I can really take advantage of this method. 

That's great, drive in an urban environment in neutral to save a fraction of a cent in fuel costs. For those who do not know, it's illegal to drive in neutral, and if you get in an accident, your PCM will record that the vehicle was in neutral at the time of airbag deployment. That information can in turn be used to file criminal (felony even) charges against you and civil charges. Don’t think it's ever happened? It happens almost daily actually. Police download infomation from vehicles' PCMs all the time when a serious injury is involved. Someone in my local area was sent to prison for 20 years after killing someone from doing exactly what you are trying to accomplish.

 

This whole concept of extreme MPG hypermiling at the cost of potentially causing tens of thousands in damage to your vehicle (taping the shutters close) or killing someone (driving in neutral) is outright absurd. If you want to save fuel that much, stop driving and get a bike. That's a pretty good way to conserve fuel, you think?

Edited August 29, 2015 by SPL Tech

[obob]

That's great, drive in an urban environment in neutral to save a fraction of a cent in fuel costs. For those who do not know, it's illegal to drive in neutral, and if you get in an accident, your PCM will record that the vehicle was in neutral at the time of airbag deployment. That information can in turn be used to file criminal (felony even) charges against you and civil charges. Don’t think it's ever happened? It happens almost daily actually. Police download infomation from vehicles' PCMs all the time when a serious injury is involved. Someone in my local area was sent to prison for 20 years after killing someone from doing exactly what you are trying to accomplish.

 

This whole concept of extreme MPG hypermiling at the cost of potentially causing tens of thousands in damage to your vehicle (taping the shutters close) or killing someone (driving in neutral) is outright absurd. If you want to save fuel that much, stop driving and get a bike. That's a pretty good way to conserve fuel, you think?

 It is not clear to me that driving in neutral is illegal in all states.

 

https://answers.yahoo.com/question/index?qid=20130515042608AAvRyeP

[revanoff2]

It occurs to me that TFT being high is what we are considering to be the main issue, with TF flow (read: lubrication) as second.

 

In this instance, I would expect that adding an Aux pump such as the Energi has would virtually eliminate the possibility of the TF getting too hot. How difficult/expensive would it be to fashion an Aux pump to this system to keep the TFT temp low? IF someone were really creative, I doubt it would cost that much.

 

SInce the Hybrid is already designed for no effective fluid cooling at times when the ICE is off, we'd only need the AUX pump to operate when the ICE is off. If you wanted to take it a step further, you could even perhaps set up a thermocouple designed to run a relay to keep the fluid temperature in check automatically, which would also aid in keeping the fluid at a decent temperature (not too low, not too high).

 

Part of the reason I mention this is because I don't know if the original warranty on mine (Built March 2013) is applicable, as I am the second owner.

 

Thoughts?

 

~Revanoff~

Edited September 4, 2015 by revanoff2

[Automate]

It occurs to me that TFT being high is what we are considering to be the main issue, with TF flow (read: lubrication) as second.

 

In this instance, I would expect that adding an Aux pump such as the Energi has would virtually eliminate the possibility of the TF getting too hot. How difficult/expensive would it be to fashion an Aux pump to this system to keep the TFT temp low? IF someone were really creative, I doubt it would cost that much.

 

SInce the Hybrid is already designed for no effective fluid cooling at times when the ICE is off, we'd only need the AUX pump to operate when the ICE is off. If you wanted to take it a step further, you could even perhaps set up a thermocouple designed to run a relay to keep the fluid temperature in check automatically, which would also aid in keeping the fluid at a decent temperature (not too low, not too high).

 

Part of the reason I mention this is because I don't know if the original warranty on mine (Built March 2013) is applicable, as I am the second owner.

 

Thoughts?

 

~Revanoff~

 

If you look at this topic http://fordcmaxhybridforum.com/topic/5288-build-date-for-ecvt-that-have-failed/  you will see I've found 3 Energi that have failed.  I think the root problem is a manufacturing defect in the transmission.  The aux pump and keeping the transmission cooler should help long term transmission life, but the defect is the main problem on the early failures.

Edited September 6, 2015 by Automate

[obob]

If you look at this topic http://fordcmaxhybridforum.com/topic/5288-build-date-for-ecvt-that-have-failed/  you will see I've found 2 Energi that have failed.  I think the root problem is a manufacturing defect in the transmission.  The aux pump and keeping the transmission cooler should help long term transmission life, but the defect is the main problem on the early failures.

 

I think this pretty much sums it up.

 

I actually wonder whether the problem can be heard long before the problem sounds like a problem.  I have noticed that my engine when regenerating is noisier that when I first bought the car. (I noticed this quite a while ago.)  I used to think it was because of some of the software upgrades, like the software makes it regenerate more, but now I am wondering if it is the transmission design problem.

 

It is not significant enough for the dealer to say, new transmission but it might be the start of the walk to the gallows, so to speak, for the transmission.

[ptjones]

"Post 76" 

 

 I have been monitoring my Trans Fluid temp since 90Kmi and it has been above 150*F on the FWY.  Most members seam to be 150*F or below.  I complained to my Dealer, but he said he couldn't do anything until it put out a code or made noise.  7kmi later it started to make a noise and 400mi after that I stopped at Rich FORD in Albuquerque, NM  and they verified it was the Trans going bad. I was on my way to AZ and decided to continue on another 350mi to Williams,AZ.  Five days later I started to go back home to GA, but decided to stop at Rich FORD again, because the noise had gotten much louder and I was afraid I couldn't make it home. I had 1100mi on the Trans since it started to make noise and I didn't want to get stranded out in the middle of no-ware.  Another benefit was Rich FORD had recently replaced a Trans in FFH so they had some experience which is very good.  FORD is paying for an Explorer Rental until the car is fixed. I will have to drive back to Rich FORD to get it.

 

What I have learned from this is:

 

1. Make sure you don't let your car get out of Warranty.

 

2. If you do mostly City driving you may never have this problem, Trans gets warmer after extended high speed driving.  I have 82% HWY driving.

 

3. The only thing that makes scents to me is that the trans pump impeller fails so Trans Fluid doesn't circulate thru cooler causing TFT to go up. I believe eventually debris ware teeth and bearings.

 

4. You can test your Trans cooler lines to see if you might have a problem by reaching down from the top of ICE compartment in front of Trans to the two cooling lines coming out of Trans.  If one line is noticeably warmer than the other you are probably OK. If they are the same temp you probably have a problem.  You also can use Digital IR Thermometer to do the same thing.

 

5. It may take upto 20Kmi to start to manifest symptoms for this problem  It is covered by 8yr/100Kmi Hybrid parts Warranty .   ;)

 

Paul