Cold weather warm up procedure

[masscommuter]

engine coolant will heat up sooner if you do NOT "turn on heat" until TEMP gauge indicates warmed-up, 6 bars or so

Originally Posted by biododge1

what I do is start car, turn on heat (auto), clear glass if needed, and wait for the "buzz" from the heater indicating that there is now "just enough" heat to warm the cab (kind of like a timer). It only takes a few minutes,. . .

[eq1]

I've been trying the heater-off method and it really does make quite a difference. Ambient temp's been around 40-50F, heater off warms up the engine within a mile or so city streets, under 40mph, up to 185F; at 185F or so you can turn the heater on and it will cool the engine temp down to about 170F, leaving lean burn enabled. With heater on under similar conditions, sometimes the engine doesn't warm up for several miles, like 7 miles... Not sure of the mpg difference, but the potential is clearly there. If all you do is short drives, a short commute, I'd say it could be up to 10, 15 mpgs... I mean, you could do the rough math if, say, lean burn saves you 20-25 mpgs, your trip is such and such length, with heater off at start lean burn's enabled so many miles sooner, etc...

[aisbell]

Seems to be a lot of effort expended and some discomfort experienced in order to minimize fuel consumption when beginning to drive in cold weather. All of this could be avoided by merely using an engine block heater wisely (assuming that one has a 120 v. outlet available).

[eq1]

A lot of effort? Turn the heater dial fully counter-clockwise; turn it back a mile or so later. The discomfort is minimal in the 40F+ weather I've endured; I can see it might become a problem at temps colder than that... Block heater: find it, buy it, install it, plug it in, plug it out - seems a lot more effort to me...

[RedJellyBean]

Originally Posted by eq1

A lot of effort? Turn the heater dial fully counter-clockwise; turn it back a mile or so later. The discomfort is minimal in the 40F+ weather I've endured; I can see it might become a problem at temps colder than that... Block heater: find it, buy it, install it, plug it in, plug it out - seems a lot more effort to me...

I'd do the cold thermo dial except I get in when the weather is 20 degrees or below, and if I turn it cold and hit the recirc button, the windows fog up pretty badly. Be glad you get to live in quite balmy, hot weather, I'd love to bask in some 40 degree glory right now

[eq1]

I suppose turning down the heat on start wouldn't be necessary with a radiator block, right? I've been meaning to install one... What's the approximate impact of a radiator block at operating engine temps - for example, are there any issues with the water cooling fan running too much once the car gets up to operating temps? I know no one probably has exact figures; just roughly, does one need to be exact when deciding how much to block to prevent the cooling fan from running too much at, say, highway speeds in 50F ambient temps?

[Eli]

I'm trying to wrap my head around how sitting and idling could ever net you better fuel economy than driving away(gently). You're getting 0MPG when sitting and idling. Anything - even 5mpg - is better than 0mpg.

Originally Posted by eq1

I suppose turning down the heat on start wouldn't be necessary with a radiator block, right? I've been meaning to install one... What's the approximate impact of a radiator block at operating engine temps - for example, are there any issues with the water cooling fan running too much once the car gets up to operating temps? I know no one probably has exact figures; just roughly, does one need to be exact when deciding how much to block to prevent the cooling fan from running too much at, say, highway speeds in 50F ambient temps?

It's still necessary. I have a 3/4 radiator block in. I'd have to look at the cooling circuit, but just based on behavior I'm guessing that coolant circulates through the heater core all the time. The radiator is only involved when the thermostat opens.

It's not a concern, especially at highway speeds. The radiator fan never comes on. I leave my block in until ambient temps get into the 70s. Even with only a couple inches of radiator available for cooling, temps stay at the normal 196 - 199F unless you're climbing a decent hill at relatively slow speeds or something. Good time to test the OBDIIC&C's coolant temperature alarm for functionality.

Coolant fan comes on at 206F. OBDIIC&C coolant temperature alarm is 217F.

[biododge1]

"I'm trying to wrap my head around how sitting and idling could ever net you better fuel economy than driving away(gently). You're getting 0MPG when sitting and idling. Anything - even 5mpg - is better than 0mpg."

your correct, in my case, the only reason I do it is what i said in my last post.

"I'd have to look at the cooling circuit, but just based on behavior I'm guessing that coolant circulates through the heater core all the time"

well yes and no. If set to "60" it shuts the water valve off. any other time its open and coolant flows

[cactus]

Eli,

My only theory is that the smaller amount of fuel used idling at the worst case situation allows you to drive off using less gas than if you had just taken off when the car is pumping in the most fuel for the coldest warm-up condition. So even if you burned a bit of gas, perhaps you drove off at 15 mpg rather than the 5 mpg, but your idling only used up some teaspoons? amount of fuel, first.

Without actually drawing a sample graph, I picture a fuel consumption vs. time chart, with the total fuel used over the test being the area under the curve. So you have a pounds per minute vs. minutes graph. If your "waste" warm up time allows the drive off to keep the total usage at a total lower volume, you made better use of the fuel. There would be some break even point where you waited too long, certainly.

If the usage of the drive off IS identical, you have simply burned the exact same amount of fuel but some extra warm-up volume added before you drove off. I think people should agree that a drive off profile when warm will use less fuel than cold, but how much difference is there after only two minutes of idling?

I just wonder if the drive-off while stone cold just uses a lot more fuel than just waiting a minute or two so the warm-up cycle has progressed further and the engine is already requiring less fuel.

Perhaps even someone that can datalog the fuel used may be able to tell more. I assume the mpg calculations monitor the rpm and pulse-width, and distance traveled. I don't know if just watching the pulsewidth by itself would tell you enough without combining with the duty cycle or RPM? Does any of the OBD info provide a fuel flow rate? Watching the pulsewidth might help if you can see obvious differences during the two drive off scenarios.

If I hadn't seen it a couple times myself, I certainly wouldn't have tried it either, but even with my daily irregularities, waiting maybe 2 minutes before driving off has given me better than average trip mileage. I am not patient enough to do it every day, but I have tried several times since I started the thread, and still think it does help. Whether actually measurable by others, was the question.

I kind of gave up on this thread because it wandered so much from my initial topic and nobody seemed interested in giving a test.

I'm surprised at how many try the grill block without even believing it would work, and they didn't even have a good way to monitor the coolant temperature. I read enough about that, and agreed that I wasn't going to test that until I had a better measurement of the temp beyond the dash gauge. And that project requires making and installing something. All my concept requires is to reset the mileage, start the car, wait maybe 2 minutes, and then do their standard commute. I've only tried this when the morning temps are somewhere from the 30 to maybe 45 degrees F. range. Colder might even be easier to confirm?

John

[biododge1]

"Does any of the OBD info provide a fuel flow rate"

short answer is no, OBD dose not have any function to measure flow. What it does do is base "flow rate" via pulse, rpm, assumed fuel psi, and oxygen content from the o2 sensors. (thats the simplified explanation. the complex way involves ecm program, st, lt fuel trim etc etc)