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Hi All

Has anyone noticed how fast the FEH/MMH warms up? How much sooner you can heat the cabin than many of the vehicle you've owned in the past? Well, your about to find out why and how to even speed up the warm-up process.

All this time I thought the strategy to use the electric motors during warm-up was to allow the oil to circulate before putting the ICE under a load. That may help the ICE last longer, but it's not the real reason Ford developed this strategy.

One of the reasons I get good gas mileage is I work hard at understanding how things work. Sometimes, or most of the time I have a hard time communicating things to everyone like saving energy by not running the heater pump. So bear with me while I try to explain what I've learned about warm-up.

It is very important to slowly accelerate from a cold start or any starts after the engine has been shutdown for over 5-10 minutes. There are a number of reasons for this which include torque demand from the ICE and conserving the battery SoC. The strategy of using the battery and electric motors for torque is to allow the PCM to retard the timing and keep the ICE running at a predetermined speed. This is to advance heating of the engine and CAT converter to go "lights-OFF" ASAP. Lights-Off is a state of the converter where the temperature is hot enough (~550 F) for the chemical breakdown of bad pollutants. Ford developed this strategy for emission reasons, not to prolong the life of the ICE as some of us first thought. The strategy also includes special battery limits to maintain the warm-up procedure. Who would have ever thought keeping the RPM's down would heat up the engine faster!

Cheers!

GaryG

I, too, have learned to be very easy on the accelerator after a cold-start. The Prius does exactly the same thing, running the engine at a set load and RPM while the battery moves the car. Too much acceleration will deplete the pack in a heartbeat, and even more will result in the ICE spinning up but the battery will keep on running down in parallel. Some of my best segments this week were after learning to do two things: 1) Don't try to creep out of the parking lot in EV mode in an attempt to delay ICE start until it is "needed." 2) Start moving immediately after the ICE has lit, but watch the energy monitor to make sure that I'm only using the little bit of power that the ICE provides in this initial warmup state. It works perfectly, as I can crawl around the parking lots at roughly 10mph without touching the battery and the ICE is totally ready to go by the time I get to the street and need to accelerate. In this case I think it works to my advantage that I have some parking lot crawling to do on both ends of my commute.

This may also explain the Japanese Prius drivers' peferred tactic of allowing initial warmup to occur while the car is stationary and then entering a warmup P&G once it is fully on-line (after roughly a minute of idling.) It could be that they don't have the "luxury" of an initial crawl and so would wind up stressing the pack with a premature run up to speed. I understand that some have had a lot of success running the Escape almost like a serial hybrid, but the Prius performs horribly in that mode relative to what it can achieve with minimal energy transfer through the battery.

One of the reasons I get good gas mileage is I work hard at understanding how things work.

And I, for one, really appreciate your efforts. Most of what I learned about driving my FEH beyond EPA expectations was by how it *felt*, without really understanding the technical *why*. Without the information I've found here, provided by you & others, my FE would have hit a permanent plateau long ago. I still may not completely understand the technical side, but from the information on what to do, I'm still seeing increases in those mpg's :)

Sometimes, or most of the time I have a hard time communicating things to everyone like saving energy by not running the heater pump. So bear with me while I try to explain what I've learned about warm-up.

... ... ...

Who would have ever thought keeping the RPM's down would heat up the engine faster!

And it works! Gary, I had been accelerating a little harder when I first started the engine, thinking I was taking advantage of those first 30 seconds, then putting a big charge into the HV battery. But the first time I took it easy right out of the garage, my ICE shut down 2 blocks from my driveway :eek: :) (I do still plug in my block heater overnight, so it was already a little warm, but before this, it would take at least 1/2mi. before the ICE shut off.) I was pleasantly amazed :):)

By starting out this way, my AM commute is coming in at 49-51mpg :):):)

And I, for one, really appreciate your efforts. Most of what I learned about driving my FEH beyond EPA expectations was by how it *felt*, without really understanding the technical *why*. Without the information I've found here, provided by you & others, my FE would have hit a permanent plateau long ago. I still may not completely understand the technical side, but from the information on what to do, I'm still seeing increases in those mpg's :)

And it works! Gary, I had been accelerating a little harder when I first started the engine, thinking I was taking advantage of those first 30 seconds, then putting a big charge into the HV battery. But the first time I took it easy right out of the garage, my ICE shut down 2 blocks from my driveway :eek: :) (I do still plug in my block heater overnight, so it was already a little warm, but before this, it would take at least 1/2mi. before the ICE shut off.) I was pleasantly amazed :):)

By starting out this way, my AM commute is coming in at 49-51mpg :):):)

That's great Debbie!

One day I was reading Ford Hybrid patents and stumbled on that one. It floored me as I was reading it. You got a real advantage if you just know how things work and make them work better in your daily drive. I don't want anyone to use my techniques with FAS if they don't want to, but you can really use FAS to a big advantage during warm-up with this Ford strategy.

So happy you confirmed the information so others can wake-up to better mileage!

GaryG

I've noticed that all modern vehicles warm up really rapidly - they tend to take roughly only half the time to reach operating temperature as the Mustangs my Dad and I have restored did. Cabin heat came on way, way faster too.

I have ordered a new 08 FEH and curently driving a 2006 VW Jetta TDI (Diesel)..some VW technology may help the warmup...VW uses two glowplugs (300 Watts total) in their coolant lines to warm up their motor faster.. Maybe Ford should do something similar to get the ICE to shut down sooner...plugging in the block heater seems like a good idea but a bit of a stretch to be pluggin it in and out each day during the summer.

I think a few of us P-II drivers have come up with a term for this... "S1 limp". (S1 is the Prius's mandatory cat converter warmup/horrible MPG/constant ICE RPM/minimized ICE draw state in the "5 stages of hybrid operation" (http://www.techno-fandom.org/~hobbit/cars/five-stages.txt)). It's better to be moving than not (otherwise you get 0 MPG instead of 10-15), but you "limp" along, like a really low speed DWL, until you know by instrumentation (ignition timing normalizes, the FCD shows a green arrow to the battery, and IMPG jumps by like 50%), or by engine noise that you are out of S1.