Re: Cold Weather Effects on the FEH/MMH
 

I have also experienced increased consumption. I have a question about EV mode. As everyone has noticed, the FEH does not go into EV mode as much or at all inthe cold. Is this due to the cold engine, or a rapidly cooling catalytic converter?

Cheers,

rcomeau

Re: Cold Weather Effects on the FEH/MMH
 

So far as we know there are no temperature sensors on the cat. EV mode is difficult (not impossible...I've seen it down to 0F for a minute or so at a time) if the HV battery is cold or the engine temperature (measured by the water temp) is cold.

The water temp can be used to kind of infer the CAT temp..... However there is the question of if the designers also want to keep the engine warm in and of itself for restarts. It is harder (and less efficient) to start a cold engine than a warm one. Also a colder engine idles higher, and runs richer increasing emmisions. Whether a water temp below 140F qualifies as a cold engine, I really don't know.... but I did want to point out that it MIGHT not just be the catalytic converter temperature that the designers were thinkng about when they set the parameters.

Re: Cold Weather Effects on the FEH/MMH
 

Based on what we've seen on our two Mariners, the idle
speed does stay on beyond the EV range much of the time
until the engine warms up. Then a short time later and
sometimes even when the "quick idle" is still on we can
"hybirdize" (spelled this way on purpose) or coast up to a
stop in EV mode from a fair distance behind allowing for
a long and gradual deacceleration. I have yet to get either
car to start out from a stopped position at an intersection
and start out and stay in EV mode whether the idle is on
or not. Even after a 60 mile highway jaunt I cannot stay
in EV mode starting out from a stop and don't expect to.
I can do it up until I put my foot on the gas peddle and
start to accelerate.

I agree about having ample air pressure in the tires. We
have both cars at 42 psi in front and 44 psi in the rear tires.
When we bumped up the tire pressure from what was in the
tires after they had left from the showroom (Bird2) and the
car lot (Bird1) with some driving around for a couple of
months on them, we no longer had as much of the low range
miles per gallon fluctuation that we had been getting at times.
We got a stabilized low mpg that the cars no longer went under
and built back up in miles per gallon from there. Until we had
two weeks of cold for us and we went back down again but our
low then was not as low as what we had prior to the added air
in the tires.

Jim

Re: Cold Weather Effects on the FEH/MMH
 

Yea, I hear that. I have been getting around 23 mpg also, I rarely look at the mpg average anymore because it only annoys me & there isn't much I can do about it anyway(I was getting over 30 in warm weather, but it's been 5º here lately)

I recently dumped the POS factory NAV system in favor of an aftermarket Eclipse setup so I lost the hybrid screens(which to me where just a gimmick anyway)with the constant mpg readout. I have my Scangauge calibrated to where it reads almost exactly the same mpg as the NAV setup did so I don't miss the displays anyway.

We had one warm day a few weeks ago(right before we had 20" of snow)& on that day I got 31 mpg so I will pretty much ignore my mpg until it warms up again.

~John

Re: Cold Weather Effects on the FEH/MMH
 

John, I know you're not interested in some of the Hypermiler techniques and many here think some of them are dangerous. For those who are interested, I've found that my mileage is improving on days the temperature is getting down in the 30-40F this winter. Of course, most of you would agree that this temperature would be considered a warm front from where your located, but this is about as cold as it gets here.

There are two reasons I feel is causing the record mileage in colder weather. First, the outside air is cooling the HV battery under heavy use of EV driving and does not require the A/C compressor to run. Second, the use of KEY-OFF FAS (forced auto stop) during warm-up. It almost seems the FEH was designed for KEY-OFF FAS because of how well it works. Normally, it takes me ~20miles to get my average in the 50mpg range from a cold start in the morning, but I hit a record for myself and did it in ~10 miles yesterday morning. Was also floored when I reached a stoplight 1.3 miles away from my house above 37mpg average from that cold start. Of course, when the light turned green, my mileage started dropping fast, as I restarted the ICE till I was at a good speed for FAS again with a great glide in "N". Soon the battery was full, had a great MPG average during the cold start and the ICE was warm enough for EV driving at that point.

Not sure at what temperature my mileage would start dropping instead of climbing in cold weather, it may be just below 32F.

GaryG

Re: Cold Weather Effects on the FEH/MMH
 

Can someone explain the physics of why running the cabin heat reduces EV mode and runs the ICE more often and for longer periods of time? I suppose I don't understand the actual "setup" of the heating system, where the heat is drawn from, and why using it has such an impact. I would think that several hundred pounds of metal and a gallon or so of coolant should retain sufficient heat that running the cabin heat shouldn't be triggering ICE startup to maintain engine temps....but I suppose my experiences are telling me I am wrong....

I ask because with the recent cold, snow, and ice, "we" (not me) have been running the heat alot....and my around town mileage has dropped from the mid twenties to about 20mpg.

Re: Cold Weather Effects on the FEH/MMH
 

Tim, there is a small heater core (radiator type element) in the duct work of your climate control system. If you place the climate control dial in any position other than off, a coolant circulating pump comes on and heat is exchanged with the cabin or outside air depending on your setting. This is why you may want to set the dial on recirculate for less cooling of coolant fluid to keep the ICE warmer. I keep the switch off, but I don't have ice or fog on the windows as much as you people in colder weather.

If the engine temperature is being cooled by both the radiator and the heater core, it's going to get cooler faster. The higher the fan setting on the climate control system, the faster the coolant is being cooled also. Some here use a radiator block in very cold weather to assist in keeping the coolant hot, but I have no need for that in my weather.

Hope this helps.

GaryG

Re: Cold Weather Effects on the FEH/MMH
 

Me too.

Once I dropped below 26MPG, I even got so disillusioned, that I stopped driving it "hybrid" style. Hey, if I can't get more than 23 MPG when the temp is in the teens, why even try? I might as well have some fun, and get some aggression out. ;)

So, some of the drop in MPG might be due to my driving too. When the outside temp raises over 40 deg again (come on global warming!), I will go back to "hybrid" style driving again.

Re: Cold Weather Effects on the FEH/MMH
 

LOL, same here. I figured if the mpg was going to suck anyway I might as well enjoy the performance it's capable of.......(these things are pretty snappy when you jump hard on the gas)

~John

Re: Cold Weather Effects on the FEH/MMH
 

Ha! Me too! We had like three weeks of temps below 32, with most of that below 10. No matter what I tried to do my tanks went down and down. 29, 28, 27, 26. So I went back to driving like an average leadfoot for a while. Today was finally warm enough that I saw my average creep up again! Woohoo! Now I'll have to re-hybridize.