Towing With C-Max Hybrid

[stratosurfer]

All,

I just started my adventure of towing with the C-Max Hybrid, I towed one of my '13 model Yamaha FX HO's around San Angelo on a 98F day and recorded temps via Bluedriver Scanner. Ski was nearly full of fuel so around 950 lbs plus the 200 lbs of the trailer so roughly 1,150 lbs. Towed up some decent hills on cruise control on freeway at 65 mph, all scanned parameters showed basically similar numbers as though I had no trailer. It is interesting how much hotter the h2o temp gets when on EV mode at a stop sign. I suppose this is the keep the stilled ICE warm and efficient. When towing I don't think I saw anything over 187F on the freeway uphill at 65mph.

I will be towing to the coast this weekend up significant grades at higher speeds (80 mph speed limits here in Texas in some areas) and I will

monitor and report back.

 

[fbov]

... It is interesting how much hotter the h2o temp gets when on EV mode at a stop sign. ...

It's heat soak. You stopped the engine, and so coolant flow. Without bulk movement, hot coolant in the cylinder head rises to the sensor. On startup, temps ought to dip a little, as it draws in coolant that cold-soaked in the radiator. 

Frank

[stratosurfer]

It's heat soak. You stopped the engine, and so coolant flow. Without bulk movement, hot coolant in the cylinder head rises to the sensor. On startup, temps ought to dip a little, as it draws in coolant that cold-soaked in the radiator. 

 

If these vehicles have electric water pumps, then coolant should still be flowing as needed irrespective of whether the engine is running or not, no? I was thinking the ECU wants to keep the engine as warm as possible after shutdown to keep it as efficient as possible when it restarts?

[plus 3 golfer]

I assume you were running A/C?  The algorithms will factor in variables such as ambient temp, ICE load, A/C load and speed (airflow through coolers) to maintain ECT between about 185 - 189 F by operating the grille shutters.  Now with A/C off, grille shutters will remain closed until ECT is around 192-195F and will fully open IIRC around 212F.  Also, IIRC thermostat is full open at 205 F.  Thus, you will normally see lower ECT with A/C on all other things being equal.  I have several posts with recorded data explaining how the grille shutters work.  

 

So, with the towing load, 75-85 mph, uphill, and 100F+, you might get ECT near 212 F based on my observations.

 

When stopped even though grille shutters are open 100%, the cooling fan is likely not providing as much air flow as driving does through the coolers and hence, even though coolant is being circulated, the heat being removed via the coolers in now less than the heat being added by the hot engine. One other point, I've never monitored the electric coolant pump (I'll record some data next time out).  For all we know, the algorithms may shut it down or reduce its speed when car is stopped to conserve energy since ECT is OK and ICE is not running. 

 

The coolant fan is generally running to remove heat from the A/C refrigerant loop not necessarily to cool ICE at low speeds as the compressor demand unlike ICE at low speeds is fairly constant.  There's no reason to "waste" energy by speeding up the fan when the ECT is normal.  Also, as fbov says, the temperature in the cylinder head (likely the hottest part of the engine) where the CHT sensor is located will likely increase. There is no ECT sensor.  ECT is an inferred value based on the CHT sensor.  

 

A lot of the data I recorded was driving through TX with cruise set at 85 mph and 100F+.  

[fbov]

... maintain ECT

... until ECT

... lower ECT

...might get ECT

... since ECT

...when the ECT

 

... There is no ECT sensor.

:lol2:

 

I never use these things, but I know of no words that express it better. Well put, Plus!

Frank

Edited June 11, 2019 by fbov

[stratosurfer]

Yes running AC.

[stratosurfer]

Update,

I towed this Waverunner 500 miles from San Angelo TX to Galveston TX via San Antonio with no problems. 97 F most of the way, 70 mph set on CC. I was light loaded inside the car, so I don’t think I went over GVRW. Trailer and Waverunner around 1,100 lbs. 80PSI as prescribed in the trailer tires, 42 in C-Max. All good.

[allen349]

keep you eye on engine heat level, it may damage you engine and transmission, I have a dodge Ram truck which i use for 24/7 towing companies near me, in truck there are some extra cooling parts who keep engine less host cause they are used for specially towing purpose and in towing engine consume more power and get hot so be care full about it.

Edited September 11, 2019 by allen349