Problems with ICE shutoff
#21
12-10-2006, 03:20 PM
Re: Problems with ICE shutoff
Hi John
Ray Martin was having problems going EV with his '05 FEH after he got off the freeway when it was cold out. I told Ray to try the "N" brake tap but I never got a response back. Like you said, it doesn't work everytime, but if I continue to hold a little pressure on the pedal, the RPM's will drop to ~1,000 and go EV if no other conditions are keeping the ICE running.
GaryG
Ray Martin was having problems going EV with his '05 FEH after he got off the freeway when it was cold out. I told Ray to try the "N" brake tap but I never got a response back. Like you said, it doesn't work everytime, but if I continue to hold a little pressure on the pedal, the RPM's will drop to ~1,000 and go EV if no other conditions are keeping the ICE running.
If the HV battery has been sitting in cold ( below freezing ) for a number of hours, I get very, very little regen, and the L gear trick is useless. The battery just can't take a charge.
But also, in very cold, it can't PRODUCE much charge either, so I think the computer deliberately holds back on going to EV as the battery would be needed to restart. However, using it is the best way to warm it. So it is a catch 22 condition. ( not sure where that phrase comes from? )
Leaving the HV battery low when you park is another good reason to have the small generator start a fast charge and begin warming the battery. The small generator also supplies power to the traction motor for a few blocks during this time. BTW, Jesse Jackson once said Pres. Clinton was in a catch 44 when they tested that stain on that DRESS. I guess that meant he had some splainning to do the taxpayers and Hillary!
The ONLY way to get EV is to have engine coolent above 141'F and enough minutes gone by ( 5 min ) to heat the cat. converter... THEN shift to N and use the double tap of the brakes method. This works most of the time, but not all the time.
Everything I've read and proof of the SG going closed loop a few blocks from my house says the CAT gets hot quick. Why don't you test how long it takes to go closed loop in the cold for us with your SG.
-John
But also, in very cold, it can't PRODUCE much charge either, so I think the computer deliberately holds back on going to EV as the battery would be needed to restart. However, using it is the best way to warm it. So it is a catch 22 condition. ( not sure where that phrase comes from? )
Leaving the HV battery low when you park is another good reason to have the small generator start a fast charge and begin warming the battery. The small generator also supplies power to the traction motor for a few blocks during this time. BTW, Jesse Jackson once said Pres. Clinton was in a catch 44 when they tested that stain on that DRESS. I guess that meant he had some splainning to do the taxpayers and Hillary!
The ONLY way to get EV is to have engine coolent above 141'F and enough minutes gone by ( 5 min ) to heat the cat. converter... THEN shift to N and use the double tap of the brakes method. This works most of the time, but not all the time.
Everything I've read and proof of the SG going closed loop a few blocks from my house says the CAT gets hot quick. Why don't you test how long it takes to go closed loop in the cold for us with your SG.
-John
#22
12-10-2006, 06:50 PM
Re: Problems with ICE shutoff
With the cold weather snap we just had, my MPG has dropped dramatically. About 4 or 5 MPG!
In the sub-freezing weather, I just can't get the ICE to shut down for any reasonable length of time. I was stuck in traffic for about 15 or 20 minutes, and during that entire time, the ICE ran. At least for me, it seemed like idle alone wasn't enough to keep the system very warm. It wasn't until the traffic started to move again, and I was able to drive at around 25MPH for 10 minutes, that the car was finally warm enough to allow the ICE to shut down. And even then, with a fully charge battery, I could not drive for more than a few minutes on EV, when the ICE would just start up again.
This is going to be my first winter with a hybrid. If this is typical cold weather operation, I don't think I am going to save very much gas.
In the sub-freezing weather, I just can't get the ICE to shut down for any reasonable length of time. I was stuck in traffic for about 15 or 20 minutes, and during that entire time, the ICE ran. At least for me, it seemed like idle alone wasn't enough to keep the system very warm. It wasn't until the traffic started to move again, and I was able to drive at around 25MPH for 10 minutes, that the car was finally warm enough to allow the ICE to shut down. And even then, with a fully charge battery, I could not drive for more than a few minutes on EV, when the ICE would just start up again.
This is going to be my first winter with a hybrid. If this is typical cold weather operation, I don't think I am going to save very much gas.
I find I've lost about 4-6MPG from my summer values even on the FREEWAY where the battery has very little to do with it and EV mode has nothing to do with it.
Try not to get discouraged. You are still saving gas... just not breaking records.
#23
12-11-2006, 12:51 PM
Re: Problems with ICE shutoff
I'm still getting 24 in the freezing cold.... the 6cylinder gets 17 (when its WARM) on the FREEWAY. You WILL save gas, just not as much. These vehicles have a 4 cylinder engine that has been made into an atkinson cycle. They save about 10% from what I've read just from that and that really has little to do with the hybrid. Everyone seems to think that EV mode is the ONLY way this car saves gas. It isn't. The car never goes into EV mode on the freeway and still gets 12MPG in the summer better than the 6cylinder model (at least for my 4WD). In the winter lets say it does drop 4-5MPG. Mine has... I'll bet the 6cylinder isn't getting 17MPG either.
I find I've lost about 4-6MPG from my summer values even on the FREEWAY where the battery has very little to do with it and EV mode has nothing to do with it.
Try not to get discouraged. You are still saving gas... just not breaking records.
I find I've lost about 4-6MPG from my summer values even on the FREEWAY where the battery has very little to do with it and EV mode has nothing to do with it.
Try not to get discouraged. You are still saving gas... just not breaking records.
If there is a strong headwind, I maybe better off taking I-95 behind a semi, which you can always find during a weekday. Playing around in EV on slower roads with no protecting may only give me ~42mpg in a strong headwind. I may be able to get that or better on I-95 drafting.
The intake of cold air has poorer efficiency burning fuel in the cylinders than hot or warm air entering the intake. Partial throttle and low RPM's are needed to give the most time for heating up the air in the intake system for a better combustion of the fuel. So I would avoid high RPM's in cold or even warm climates for the best FE. Lets face it, low RPM's is best all the time for FE.
GaryG
#24
12-12-2006, 04:20 AM
Re: Problems with ICE shutoff
Are you sure about that?
Most cars today, try to get colder air for their intake, and why they now suck in air from in front of the radiator instead of behind it. And with HP sports cars, one uses a scoop to try to catch as much cold air as possible.
Cold air is denser, and therefore, holds more oxygen.
#25
12-12-2006, 05:35 AM
Re: Problems with ICE shutoff
Are you sure about that?
Most cars today, try to get colder air for their intake, and why they now suck in air from in front of the radiator instead of behind it. And with HP sports cars, one uses a scoop to try to catch as much cold air as possible.
Cold air is denser, and therefore, holds more oxygen.
Most cars today, try to get colder air for their intake, and why they now suck in air from in front of the radiator instead of behind it. And with HP sports cars, one uses a scoop to try to catch as much cold air as possible.
Cold air is denser, and therefore, holds more oxygen.
Cold air isn't more fuel effiecient, but it can produce more horsepower with more fuel consumed--mainly due to density differences I believe hence the reason for superchargers and turbochargers.
#26
12-12-2006, 05:40 AM
Re: Problems with ICE shutoff
Thats true... but you are talking a sports car.... its not exactly designed for fuel efficiency. Cooler/denser air will allow you to produce more torque and horsepower, but you shoot in more fuel to keep the fuel/air ratio the same and your gas mileage goes south.
Cold air isn't more fuel effiecient, but it can produce more horsepower with more fuel consumed--mainly due to density differences I believe hence the reason for superchargers and turbochargers.
Cold air isn't more fuel effiecient, but it can produce more horsepower with more fuel consumed--mainly due to density differences I believe hence the reason for superchargers and turbochargers.
Couldn't have said it any better!
GaryG
#27
12-12-2006, 09:34 AM
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Join Date: Sep 2006
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Re: Problems with ICE shutoff
Thats true... but you are talking a sports car.... its not exactly designed for fuel efficiency. Cooler/denser air will allow you to produce more torque and horsepower, but you shoot in more fuel to keep the fuel/air ratio the same and your gas mileage goes south.
Cold air isn't more fuel effiecient, but it can produce more horsepower with more fuel consumed--mainly due to density differences I believe hence the reason for superchargers and turbochargers.
Cold air isn't more fuel effiecient, but it can produce more horsepower with more fuel consumed--mainly due to density differences I believe hence the reason for superchargers and turbochargers.
Cold, dense intake airflow, along with the "appropriate" level of fuel mixed in, allows the engine to operate at a lower RPM to produce a given level of HP, reduced frictional losses..
Much the same effect as switching to a higher octane fuel.
If your statements were correct then FE should improve with altitute, and we all know that it doesn't.
That being said I'm sure that there is a point wherein the incoming airflow would be too cold for efficient combustion but I'm not sure any of us will experience that level outside of Prudhole Bay.
#28
12-12-2006, 09:57 AM
Re: Problems with ICE shutoff
If you maintain the same compression ratio and spark timing and go to a high octane fuel, you will not gain power. You may lose power due to the higher octane's resistance to ignite vs. the lower octane.
#29
12-12-2006, 10:04 AM
Re: Problems with ICE shutoff
Sorry, this is just WRONG...
Cold, dense intake airflow, along with the "appropriate" level of fuel mixed in, allows the engine to operate at a lower RPM to produce a given level of HP, reduced frictional losses..
Much the same effect as switching to a higher octane fuel.
If your statements were correct then FE should improve with altitute, and we all know that it doesn't.
That being said I'm sure that there is a point wherein the incoming airflow would be too cold for efficient combustion but I'm not sure any of us will experience that level outside of Prudhole Bay.
Cold, dense intake airflow, along with the "appropriate" level of fuel mixed in, allows the engine to operate at a lower RPM to produce a given level of HP, reduced frictional losses..
Much the same effect as switching to a higher octane fuel.
If your statements were correct then FE should improve with altitute, and we all know that it doesn't.
That being said I'm sure that there is a point wherein the incoming airflow would be too cold for efficient combustion but I'm not sure any of us will experience that level outside of Prudhole Bay.
For power, you want cold dense air because are pouring in so much gasoline the engine is oxygen starved unless you and increase the density by compressing the air (turbo, supercharger) and sometimes cool it with an intercooler (to allow even higher density) to get more air in there. This has little to do with increasing MPG and more to do with getting maximum HP for a specific engine.
NOW it CAN and IS used to help MPG by putting an engine in that is too small to produce the HP a car needs and then adding a turbocharger compressing the air and boosting the HP of that small engine. This is done on some of the VWs for example.
But we are talking our FEH engine which is a fixed size... I can't shrink it on the fly and get denser air into it... get the same HP with less fuel. I'm going to suck more fuel because the engine size/fuel ratio/etc isn't optimized to drive my vehicle at cold temps... its optimized at "normal" temps.
At high altitude you are oxygen starved all the time. So the car runs poorly and gets poor MPG. However you can certainly build a car that runs better up there than one designed for "sea level" will... and it will probably run like crap at sea level and get bad MPG at sea level and "better" at high altitude.
The extremes are rarely ever good in real life unless you optmize for those rare cases.
#30
12-12-2006, 10:06 AM
Ridiculously Active Enthusiast
Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: Problems with ICE shutoff
Superchargers and Turbochargers....
Let's correct a serious misconception...
The Maxda Millennia S used a Supercharger, but not in the traditional "sports car" sense.
It was used to improve FE by ~23%......!!
The Maxda engine started out "life" as an Atkinson Cycle engine, a longer power/combustion stroke, virtually, than the compression stroke.
Remember that "wasted" energy that would be best used to turn a turbocharger?
The atkinson cycle uses it before it reaches the exhaust.
The longer power/combustion stroke allows a more complete "burn" of the A/F mixture.
The actual/physical compression ratio of the Mazda engine is 13:1 but is reduced to ~10:1 by releasing some of the A/F mixture back into the intake chamber during the compression stroke.
The net result from the use of the Atkinson cycle is about 20-30% improvement in FE while at the same time reducing the output of a given size/displacement engine by 20-30%So Mazda used a Supercharger to bring the (now Miller Cycle) engine output back up to the HP rating of a standard Otto engine of equivalent displacement.
Yes, Superchargers and Turbochargers can and are used to boost HP ratings in the racing venue.
But they, at least the SC, can also be used to allow good FE for cruising along while at the same time providing STELLAR performance out of that otherwise smallish engine when/if you put your foot into it.
I'm awaiting the day that someone produces a Miller Cycle engine using a positive displacement variable speed SC is to replace the throttle valve. The SC would be indirectly driven by the engine, but speed independent of the engine, via a CVT arrangement much like the CVT in your FEH/MMH today.
While cruising along at a relatively constant speed the SC would supply only enough air flow for a given engine speed/load. But above 2/3 "throttle" it would begin supplying a constant, controlled, level of BOOST.
Let's correct a serious misconception...
The Maxda Millennia S used a Supercharger, but not in the traditional "sports car" sense.
It was used to improve FE by ~23%......!!
The Maxda engine started out "life" as an Atkinson Cycle engine, a longer power/combustion stroke, virtually, than the compression stroke.
Remember that "wasted" energy that would be best used to turn a turbocharger?
The atkinson cycle uses it before it reaches the exhaust.
The longer power/combustion stroke allows a more complete "burn" of the A/F mixture.
The actual/physical compression ratio of the Mazda engine is 13:1 but is reduced to ~10:1 by releasing some of the A/F mixture back into the intake chamber during the compression stroke.
The net result from the use of the Atkinson cycle is about 20-30% improvement in FE while at the same time reducing the output of a given size/displacement engine by 20-30%So Mazda used a Supercharger to bring the (now Miller Cycle) engine output back up to the HP rating of a standard Otto engine of equivalent displacement.
Yes, Superchargers and Turbochargers can and are used to boost HP ratings in the racing venue.
But they, at least the SC, can also be used to allow good FE for cruising along while at the same time providing STELLAR performance out of that otherwise smallish engine when/if you put your foot into it.
I'm awaiting the day that someone produces a Miller Cycle engine using a positive displacement variable speed SC is to replace the throttle valve. The SC would be indirectly driven by the engine, but speed independent of the engine, via a CVT arrangement much like the CVT in your FEH/MMH today.
While cruising along at a relatively constant speed the SC would supply only enough air flow for a given engine speed/load. But above 2/3 "throttle" it would begin supplying a constant, controlled, level of BOOST.
