Warm-Up
#1
06-23-2007, 02:13 PM
Warm-Up
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
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
#2
06-23-2007, 08:37 PM
Hybrid and Ethanol Expert
Join Date: Mar 2005
Location: All over the Central U.S.
Posts: 3,616
Re: Warm-Up
I agree with everything posted so far, except the very last line is mis-leading.
"Who would have ever thought keeping the RPM's down would heat up the engine faster!"
The first 30 seconds of burning fuel puts the most pollution out the tailpipe. By keeping RPM down during this initial start up time, you are keeping fuel use down during this time, and you are putting less "fumes" though a cold catalytic converter. So yes, taking it easy, and letting the electric motor do the work during the first 30 seconds is a big plus.
The engine will warm up slowly at low RPM, but it will warm up more cleanly at lower RPM. No doubt, flooring it to 5900 RPM will heat the engine faster... but you'll dump a lot of crap out the back in the process.
I'm confident you knew this Gary.
You were just testing me, weren't you!
-John
"Who would have ever thought keeping the RPM's down would heat up the engine faster!"
The first 30 seconds of burning fuel puts the most pollution out the tailpipe. By keeping RPM down during this initial start up time, you are keeping fuel use down during this time, and you are putting less "fumes" though a cold catalytic converter. So yes, taking it easy, and letting the electric motor do the work during the first 30 seconds is a big plus.
The engine will warm up slowly at low RPM, but it will warm up more cleanly at lower RPM. No doubt, flooring it to 5900 RPM will heat the engine faster... but you'll dump a lot of crap out the back in the process.
I'm confident you knew this Gary.
You were just testing me, weren't you!
-John
#3
06-23-2007, 09:40 PM
Re: Warm-Up
I agree with everything posted so far, except the very last line is mis-leading.
"Who would have ever thought keeping the RPM's down would heat up the engine faster!"
The first 30 seconds of burning fuel puts the most pollution out the tailpipe. By keeping RPM down during this initial start up time, you are keeping fuel use down during this time, and you are putting less "fumes" though a cold catalytic converter. So yes, taking it easy, and letting the electric motor do the work during the first 30 seconds is a big plus.
The engine will warm up slowly at low RPM, but it will warm up more cleanly at lower RPM. No doubt, flooring it to 5900 RPM will heat the engine faster... but you'll dump a lot of crap out the back in the process.
I'm confident you knew this Gary.
You were just testing me, weren't you!
-John
"Who would have ever thought keeping the RPM's down would heat up the engine faster!"
The first 30 seconds of burning fuel puts the most pollution out the tailpipe. By keeping RPM down during this initial start up time, you are keeping fuel use down during this time, and you are putting less "fumes" though a cold catalytic converter. So yes, taking it easy, and letting the electric motor do the work during the first 30 seconds is a big plus.
The engine will warm up slowly at low RPM, but it will warm up more cleanly at lower RPM. No doubt, flooring it to 5900 RPM will heat the engine faster... but you'll dump a lot of crap out the back in the process.
I'm confident you knew this Gary.
You were just testing me, weren't you!
-John"Another method of controlling exhaust emissions is to provide a mechanism for quickly heating the catalyst to reduce the amount of time it takes the catalyst to reach its activation temperature. One way to quickly heat the catalyst is to retard the spark timing of the engine. This causes the catalyst to be heated more quickly, but results in a loss of engine power. Thus, if a driver demands an increase in engine power, the spark retard must be reduced, which causes the catalyst to be heated more slowly, and results in more exhaust emissions being introduced into the atmosphere."
My intent was to address the reason why the electric motors provide torque during warm-up in the FEH/MMH. The key is to let the strategy proceed by not demanding more torque (acceleration) from the ICE during this warm-up period. This is not a GaryG technique, this is Ford engineers at their best. What I'm hoping readers will understand is why the ICE remains at a predetermined idle during acceleration and warm-up. Those that accelerate harder are causing the catalyst to heat up slower and therefore increasing the time to go EV.
GaryG
#4
06-23-2007, 10:04 PM
Hybrid and Ethanol Expert
Join Date: Mar 2005
Location: All over the Central U.S.
Posts: 3,616
Re: Warm-Up
What I said was ( and still is ) correct.
I did not miss FORD's point at all.
What you meant in your first post was correct.
What you said was wrong.
You said:
"Who would have ever thought keeping the RPM's down would heat up the engine faster!"
What you meant is, and finally posted in your second post (from Ford):
"One way to quickly heat the catalyst is to retard the spark timing of the engine."
The two bold statements above are not the same.
And notice the phrase "one way".
Hold your hand over a lit candle and your hand will get hot fast.
Will the whole room get hot fast?
I was being nice in clarifying your misleading post.
I did not miss FORD's point at all.
What you meant in your first post was correct.
What you said was wrong.
You said:
"Who would have ever thought keeping the RPM's down would heat up the engine faster!"
What you meant is, and finally posted in your second post (from Ford):
"One way to quickly heat the catalyst is to retard the spark timing of the engine."
The two bold statements above are not the same.
And notice the phrase "one way".
Hold your hand over a lit candle and your hand will get hot fast.
Will the whole room get hot fast?
I was being nice in clarifying your misleading post.
Last edited by gpsman1; 06-25-2007 at 12:33 PM.
#5
06-23-2007, 11:15 PM
Re: Warm-Up
What I said was ( and still is ) correct.
I did not miss FORD's point at all.
What you meant in your first post was correct.
What you said was wrong.
You said:
"Who would have ever thought keeping the RPM's down would heat up the engine faster!"
What you meant is, and finally posted in your second post (from Ford):
"One way to quickly heat the catalyst is to retard the spark timing of the engine."
The two bold statements above are not the same.
And notice the phrase "one way".
Hold your hand over a lit candle and your hand will get hot fast.
Will the whole room get hot fast?
I was being nice in clarifying your misleading post.
You started off well in post #1 but are starting to get snooty again.
THINK before making a rushed response.
I did not miss FORD's point at all.
What you meant in your first post was correct.
What you said was wrong.
You said:
"Who would have ever thought keeping the RPM's down would heat up the engine faster!"
What you meant is, and finally posted in your second post (from Ford):
"One way to quickly heat the catalyst is to retard the spark timing of the engine."
The two bold statements above are not the same.
And notice the phrase "one way".
Hold your hand over a lit candle and your hand will get hot fast.
Will the whole room get hot fast?
I was being nice in clarifying your misleading post.
You started off well in post #1 but are starting to get snooty again.
THINK before making a rushed response.
GaryG
#6
06-24-2007, 04:41 AM
Re: Warm-Up
You two crack me up. I am new here. It seems to me that this goes on in every post you both make.
If you two ever worked TOGETHER, the whole site would benefit greatly.
But for now the information is great and the entertainment value is right up there too LOL.
show some respect for each other geesh....
08FEH
If you two ever worked TOGETHER, the whole site would benefit greatly.
But for now the information is great and the entertainment value is right up there too LOL.
show some respect for each other geesh....
08FEH
#7
06-24-2007, 04:11 PM
Re: Warm-Up
Do you think maybe both phenomena are at play here? Low rpm means lower emissions while the CAT warms up and the PCM is able to alter the timing which, as Gary describes it, heats the engine faster?
Cheers,
rcomeau
Cheers,
rcomeau
#8
06-24-2007, 06:15 PM
Re: Warm-Up
I'm still annoyed that Ford went with the "ICE-on for every start" in the first place. Toyota hybrids will start up and run in EV from the get-go with enough battery power. I know that Ford's "reason" was because they felt that consumers would expect the engine to start when they turn the key and might be confused when it doesn't. Toyota's customers figured it out, but I am stuck having to waste gas when my battery has plenty of juice to get me going. As for heating the CAT....well, it could wait and run the same "program" when the ICE came on to recharge the battery a few minutes down the road. Besides, "the average consumer" isn't buying FEH's and MMH's anyway!
#9
06-24-2007, 07:01 PM
Hybrid and Ethanol Expert
Join Date: Mar 2005
Location: All over the Central U.S.
Posts: 3,616
Re: Warm-Up
It is technically illegal for a Toyota to drive away from a cold start on battery alone. Toyotas sold in the U.S. do not come with the option to pull away from a cold start in EV mode. This is a DIY ( Do it yourself ) modification that some poeple made, since cars sold in foreign markets are capable of using EV from a cold start. Search for "Prius EV button" for more details.
Ford did not really choose to make the engine start mandatory.
Ford is following U.S. Law. ( EPA law IIRC )
Ford did not include an "EV button" option, probably because Ford sells so few cars overseas.
Ford did not really choose to make the engine start mandatory.
Ford is following U.S. Law. ( EPA law IIRC )
Ford did not include an "EV button" option, probably because Ford sells so few cars overseas.
#10
06-24-2007, 07:11 PM
Re: Warm-Up
Note: The term is "converter light-off", not converter lights off. Yes, I'm nit picking. As mentioned above, the catalyst must get hot to work. The generally accepted (meaning the SAE uses it) term for that state is "catalytic converter light off". It gets lit, like a fire. Once the catalyst lights-off, it works.
All modern cars (including the FEH) will run at 1500+ RPM for about 2 minutes when cold to hasten converter light-off. This unloaded fast idle is not good for the engine, but is necessary to get the converter hot during the "emissions challenge period" (as some engineers call it), which is the first 100 seconds after a cold start. Once the converter reaches operating temperature, the idle will drop to normal.
To test this, cold start your FEH and watch the tach. Initial idle will be high. Wait a few minutes and the idle drops, either all at once or in stages. The drop to normal idle means your converter is operational. It's lit, so to speak.
Interestingly, both the Prius and the FEH delay ICE engagement until higher road speeds during this period. I first noticed this on my old Prius back in late '03, and attributed it to a designed-in strategy to control emissions by delaying putting the ICE under load until light-off had occurred.
Is this the phenomenon we are talking about? If so, you're correct that the FEH does this. I admit I did not read all these posts, just the first one.
All modern cars (including the FEH) will run at 1500+ RPM for about 2 minutes when cold to hasten converter light-off. This unloaded fast idle is not good for the engine, but is necessary to get the converter hot during the "emissions challenge period" (as some engineers call it), which is the first 100 seconds after a cold start. Once the converter reaches operating temperature, the idle will drop to normal.
To test this, cold start your FEH and watch the tach. Initial idle will be high. Wait a few minutes and the idle drops, either all at once or in stages. The drop to normal idle means your converter is operational. It's lit, so to speak.
Interestingly, both the Prius and the FEH delay ICE engagement until higher road speeds during this period. I first noticed this on my old Prius back in late '03, and attributed it to a designed-in strategy to control emissions by delaying putting the ICE under load until light-off had occurred.
Is this the phenomenon we are talking about? If so, you're correct that the FEH does this. I admit I did not read all these posts, just the first one.
