What if I warm my car up by driving it, but the rpms never reach 1500rpms. What effect does this have on the warm up cycle?

I, for one, drive my car to warm it up. I'm not going to sit around for 20+ minutes waiting for my water temp to get to normal operating temperature. It even states in my Honda manual that 30 seconds is more than enough warm/start up time.

 

Ok, now you're not paying attention and you're twisting things around to suit yourself. Read that paragraph I wrote and tell me if that was my meaning. Idling the car also burns excessive fuel, and it's even more excessive because you're not even moving.

I contend that it reduced warmup times by a significant amount. You can verify this easily enough with a stopwatch and your own eyes, although the stock coolant temperature gauge hardly passes for a measuring device. You cannot argue the fact that applying more load to the engine increases the rate of heating, and by a great amount. You're releasing more energy from the fuel, and creating more heat. If this is not evident, it's time for high school physics again.

By saying that driving away without warming up the car adds excessive fuel to the exhaust completely ignores the fact that sitting there idling does the same thing, for a longer period of time. And it does it with less exhaust volume to heat the catalytic convertor to operating temperature. It is not uncommon for a cat to fall below it's light off temperature due to periods of idling, sometimes after just a couple minutes, and that's after it has been driven on and reached operating temperature. So being stone cold, it's not going to heat up very much at all just sitting there idling.

In addition, overheating damage to the catatlyic convertor due to excessive unburnt fuel isn't much of a problem when you're trying to heat it up. That is part of the reason why cars run rich when they're cold! To heat up the catalytic convertor faster and get the car running efficiently and burn the fuel off the cat! By sitting there and not putting heat into the system, you're just prolonging the amount of time the cat is not functioning, and introducing an excessive amount of fuel into it.

I know my O2 sensor reaches operating temperature in less than 20 seconds. You know how I know this? Because Bosch said so, and they made the sensor. In the technical specifications of the sensor, which is what the OEMs use to choose suppliers for their parts, they specify less than 20 seconds of warmup time for any time in the sensors life, in 20 degree C ambient air temperatures. I guarantee the ambient air in the exhaust is greater than 20 degrees C, and Bosch notes that lightoff time can be significantly less depending on exhaust gas temperatures.

I have already shown that it will reach operating temperature in far less than 30 seconds. Furthermore, heating a tiny section of zirconium up a few hundred degrees is nothing like heating a 30 lb piece of metal that is sinking the heat into the air as the exhaust is trying to heat it. Here's an experiment for you. Time how long you can hold your hand on the exhaust with the car idling. Then let the car cool completely, start it and drive it for half that time. Shut it off and touch the exhaust. I haven't done this, but I have a pretty good guess what will happen.


I have already shown that the O2 sensor will. The cat might not, depending on whether you're sitting there idling or not.

The EPA is stating that it doesn't operate efficiently until it's warmed up. And what do we know about warming up an engine? That it happens faster when you drive it! The faster you can warm up the engine, the more quickly you'll enter the efficient operating conditions of the engine, and the less fuel you will consume, and have consumed reaching that point. That is what you must realize.

Once again, I would like to see any evidence you can find that supports the argument that idling the car to warm it up consumes less fuel than starting it and driving away.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by goldenstreets &raquo;</TD></TR><TR><TD CLASS="quote">So if you can find an article that specifically states, that cold start up and immediate drive away is better than follow at lest manufactuers recommended warm up period, then I will yeild.</TD></TR></TABLE>

I'll read the rest of your post tommorow, as it's late and I have class early. But despite the couple pieces of evedence I have already shown you, you still see a need for more. That's not hard. A simple google search for "fuel economy warm up" yields plenty of material. Just in the first few pages alone, I found these links:

http://www.cartalk.com/content...onomy/
http://eartheasy.com/live_fuel...g.htm
http://www.dcu.org/streetwise/september2005.html
http://www.fueleconomy.gov/feg/factors.shtml
http://auto.consumerguide.com/....html
http://oee.nrcan.gc.ca/transpo...ttr=8
http://www.consumerenergycente....html
http://www.stonyfield.com/Eart...r.cfm

All these sites are about improving fuel economy. And they all mention reducing idle time, especially when first starting a car. That last one is my favorite, because even a yogurt company knows:

""Warming up" is not necessary for most cars today and in most cases is a waste of fuel and time. In fact, according to a study by the Healthy City Office in Toronto, any more than ten seconds of idling uses more fuel than shutting off and restarting the engine. The study also showed that cars are best warmed up by starting out slowly when driving, which cuts engine warm-up times in half and saves fuel."

"Warming up" is a waste of fuel... Cars are best warmed up by starting out slowly when driving, which saves fuel. I don't know what more you want.

Note that for most of those sites, whenever they mention idling before driving away during a cold start, they mention it with "winter" and "extremely cold" and things like that. And even then, they specify to idle for the least amount of time possible.

If you really want to get nitty gritty, I found an article for the SAE, which right away should tell you it's nerdy. But it really breaks it down:

http://www.ctts.nrel.gov/analy...9.pdf

Page 14 tells it all: "Energy Cost of Having a Pre-Cycle Warm-Up (while stationary)"

Note that the longer the vehicle is stationary, the lower the cumulative fuel economy over the span of the test.

If you want any more evidence, you don't have to look hard to find it, although honestly I don't see what else you would want to see.

I looked at the articles you posted, and in none of them do I see anything about improving fuel economy, cold starts, or driving the car before it's warmed up. Once again the question is not about the catalytic convertor, but fuel consumption.

You can do whatever you like with your car, but at least realize what is really happening. After everything I've shown you, do you still really believe that sitting with the engine running is a good use of fuel?

 

If you only knew how much cylinder wash you get by driving in a cold air configuration, you would realize that your rings will last a lot longer if you allow the engien to warm up to running temp before driving off.

The key words there are "Running" and "Temperature." If running temperature was ambient air temperature, there would never be a need to define it as "Running temperature." Know what I mean?

But one good thing about living in Texas... In the summer with a black hood, I am almost at running temperature before I turn the key... LOL!


However, I remember when I was in the service and was stationed in Alaska, we used to plug in our cars just about everywhere. This was, of course to warm the engine oil prior to start-up to reduce damage to the bearings, etc....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cuda70 &raquo;</TD></TR><TR><TD CLASS="quote">If you only knew how much cylinder wash you get by driving in a cold air configuration, you would realize that your rings will last a lot longer if you allow the engien to warm up to running temp before driving off</TD></TR></TABLE>

Do YOU know? I have a widband in my car, and it runs no richer on a cold start than it does getting on the highway, and it takes 2 minutes of driving to get from the 13:1 AF ratio it starts with to the 14.7:1 we all know and love. So I do know what is happening in my engine, I don't think others know.

You asked for evidence, and when provided, you refute it. I have still seen no evidence to support your point, so I don't even have anything to argue with, only your circular arguments and the red herring of cataytic convertor damage you keep waving for some reason. Your self-righteous attitude is blinding you, and I see that no amount of argument can convince you. I will leave this thread now, as it is a waste of my time and energy to engage in this idle conversation. Goodbye, sir.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote">

Do YOU know? I have a widband in my car, and it runs no richer on a cold start than it does getting on the highway, and it takes 2 minutes of driving to get from the 13:1 AF ratio it starts with to the 14.7:1 we all know and love. So I do know what is happening in my engine, I don't think others know.
</TD></TR></TABLE>

Unfortunately it isn't that simple. Cylinder wash is large quantities of fuel that didn't burn because it didn't atomize. If it doesn't burn it doesn't use up any oxygen, and if it didn't use up any oxygen it won't reduce the oxygen content of your exhaust. Just because your wideband tells you that the mixture is stoichiometric you can't guarantee that there isn't extra gasoline on the still-cold engine parts. An O2 sensor only tells you about the air and fuel that TOOK PART in the combustion event. That much unburned fuel is essentially outside the control volume that is your combustion chamber, especially when it washes down past the rings.

Here's an experiment for you, since the ONLY WAY this will be resolved is with actual data. If you just start and drive like I had been doing before this week, go take a whif of your oil. Smell the gas? It had to come from somewhere and it's NOT supposed to be there. Personally, I'll be keeping an eye (or nose) on it from this point forward.

 

What is normal operating temp?

 

And while you are waiting for the engine to come up to temp, you can do something constructive like meditate. Or totally annoy your hated neighbors by blasting your system. (One of my favorites early in the morning!) LOL

 

In an attempt to find real information to answer this question I did a quick google search on "oxygen sensor warmup time and found this article:

http://www.picotech.com/auto/lambda_sensor.html

Here's a key excerpt for those who don't care to read the whole thing:
"To reduce the warm-up time of the Lambda sensor, an internal heating element may be used. Heated O2 sensors can reach an operating temperature of as high as 500 degrees C in as little as eight seconds! Shorter warm-up time means the system can go into closed loop fuel control sooner, which reduces emissions and improves fuel economy. Heating the sensor also means it can be located further downstream from the exhaust manifold."

8 seconds? That's fast! This suggests that those of us who drive cars with modern heated oxygen sensors don't really need to worry about this piece of the puzzle. Waiting just a few seconds, which most of us probably do, brings the O2 sensor into full operation.

Now, this still doesn't mean that you aren't going to dump extra fuel into a cold engine. There are plenty of other factors to worry about, which have been beaten to death. I just thought some of you might like to see that.

I'm approaching 1/2 tank with roughly 190mi driven, which is more or less what I would expect. The first 80 miles of the tank were on the highway so I have half a mind to fill up soon regardless of mileage so that I can do a week of purely around-town driving with consistent warmups.

**EDIT**
Found some more information.

http://www.kemparts.com/TechTalk/tt07.asp

...the computer is programmed not to go into closed loop operation until the coolant temperature sensor tells the computer the engine is warmed up. If the system tries to go into closed loop too early in the warm-up period, the leaning effect of the system would cause driveability problems and pollutants.

So this basically says that it doesn't matter if the O2 sensor is warmed up in 8 seconds because the computer won't pay attention to it until the engine is warm. The "leaning effect" is the formation of gasoline film on cold metal parts, which prevents fuel from participating in combustion. That's why the engine has to run rich while cold. Again, already been beaten to death. Just trying to provide credible information!




Modified by exbrick at 11:01 AM 10/20/2005

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by exbrick &raquo;</TD></TR><TR><TD CLASS="quote">
**EDIT**
Found some more information.

http://www.kemparts.com/TechTalk/tt07.asp

...the computer is programmed not to go into closed loop operation until the coolant temperature sensor tells the computer the engine is warmed up. If the system tries to go into closed loop too early in the warm-up period, the leaning effect of the system would cause driveability problems and pollutants.

So this basically says that it doesn't matter if the O2 sensor is warmed up in 8 seconds because the computer won't pay attention to it until the engine is warm. The "leaning effect" is the formation of gasoline film on cold metal parts, which prevents fuel from participating in combustion. That's why the engine has to run rich while cold. Again, already been beaten to death. Just trying to provide credible information!
</TD></TR></TABLE>


Sounds like it's more efficient to get the engine up to normal operating temps as quick as possible.

 

My dick's bigger than yours. Sorry, had to do it.

 

can someone break that all down lol thats a lot of reading

 

Who cares when I go to pump I just close my eyes and pump.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by VTHONDABOY &raquo;</TD></TR><TR><TD CLASS="quote">Who cares when I go to pump I just close my eyes and pump. </TD></TR></TABLE>LOL... I have to try that