Warming your car up in cold weather

[ps2fixer]

Just my 2 cents

My yard buggie is a 1985 GMC S-15, it is really cold blooded, problably needs a good carb tuned. Once it is warm, it runs fine.

Both my cars I drive (92 camry and 97 corolla) both start and are ready to go any time except they won't shift into OD until the temp gauge just starts to move. That is 130*F with my scangauge on the 97.

Having a scangauge and a mother that is aginst getting in a cold car, I can see the huge differences in my average MPG for the trip with warming up vs just taking off. Somewhere in the lines of 32mpg vs 39mpg on ~30 min drive.

[MetroMPG]

That's a really interesting specific case (with the transmission being held in a lower gear, or preventing torque converter lockup, below a certain coolant temp). If your drive takes you out onto the highway soon after starting, it seems possible.

It'd be interesting to see this tested.

Of course, a coolant heater is still the best option!

[ps2fixer]

Originally Posted by MetroMPG

That's a really interesting specific case (with the transmission being held in a lower gear, or preventing torque converter lockup, below a certain coolant temp). If your drive takes you out onto the highway soon after starting, it seems possible.

It'd be interesting to see this tested.

Of course, a coolant heater is still the best option!

What is it that you would like to see tested? I have two Toyotas that do it of my own, and my parents both own Toyota Camrys, they all do the same thing for holding 3rd gear till the temp gauge just starts to move.

On my corolla... right when the temp on my scan gauge says 130, it instantly shifts, this has been done several times, and when i'm running late, it will R around 3k rpm for 60mph and still won't shift till it heats up. I'm not sure what temp the Camrys require since they are older than 96 and I can't scan them with my scangauge.

I did a quick search and answers seem to say it is either to prevent engine damage or for emission control. I would guess emissions since reving the engine when it is cold I would think would be more damaging than having it work harder at a lower speed in overdrive.

[gone-ot]

...the Pontiac Vibe (nee' Toyota Matrix) engine/transmissions do the samething, hold-gear when cold...even states so in the Owners Manual.

[roosterk0031]

I recall the stratus holding drive when cold, but since only 2 drivers in the house, I'm parked inside. When at work if in single digits F, I can't let it get that cold. One of the belts, I think PS, will slip so I can't take the chance of letting it get to ambient temp when below the teen's F. I'll take it for a drive over lunch, otherwise it may smoke the belt at 5.

If above teens, hit the key and drop it in gear regardless of what car I'm driving, after 250k on malibu and 216k on stratus I think it's working OK.

Edit: I guess I should add my attached garage with radiant floor heat is only 4 years old, the car's endured cold starts most of their lives. I do also have a detacted garage so they never got warm up while scraping, start and go.

[Frank Lee]

Tighten that belt.

[SentraSE-R]

First generation Scion xB ATs are also lumped into the Toyota AT cold temperature no-top gear shift programming (137 F is the magic number for them). I suspect it may be true of several Toyota transmissions.

[MetroMPG]

Originally Posted by ps2fixer

What is it that you would like to see tested?

I just thought it would be interesting to know where the "break even" point is.

EG: how much distance do you have to cover in 4th gear lockup (at relatively high MPG) to offset the fuel burned sitting in the driveway (at zero MPG)?

I suspect the math works for longer trips, but less so for short ones.

[Frank Lee]

I thought the cold trans top gear lock-out was common if not across the board on electronically controlled a/ts? My '94 F150 locks out until warm too; always has.

[ps2fixer]

I understand now, with starting temps mid 30s to low 40s, I have to drive around 2 miles before it hits 130F and it goes into lockup. While driving I get around 30mpg according to my scangauge at around 40mph and somewhere around 2000-2100 rpm. Once it shifts into OD MPG jumps up to about 35mpg and I have to speed up to about 47mph to get lockup to kick in and the mpg goes to 38-40ish at 45mph steady speed. When the car is fully warmed up it gets about 43-45 mpg at 45mph.

I would say taking off right away is much more efficient, idling while warming up it is over 2 gal / hour with the 1.8L and RPM is between 1200-1400 depending on the day, the computer in the car is kind of strange I guess.

Also, 95% of my trips are 20 miles + so letting it warm up would just eat more fuel. Super short trips it might help the engine to be warmed up, but I don't think there would be a savings since every other sunday I leave the car warm up about 5 mins to make my mom happy and the mpg average is hard to get over 30 going 50mph (38-40mpg at steady speed) for a 20 mile trip.

Now a figure I would be interested in would be to force it to over ride the temp requirement to shift into OD/lockup and see how much MPG increases.

Last nights trip to work had a trip log of max speed 47mph, max rev around 2400, distance of 36 miles, and I think the average was 43mph and average MPG was 41.5. There are 3 stops and 4 turns counting turning into the parking lot. Oh and EPA rating is 26 average, 31 highway. Only mods are 55psi in tires, upper grill block, and sealed front and sides of hood with foam tape.