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Letting car warm up-questions

Chadgervais

Chadgervais

Former GP Owner
I wasnt quite sure how to phrase the title of this thread, but this is what Im wondering.

I know when its cold out and the engine is cold, its bad to start it up and immediately drive aggressively. I also know there is much debate as to whether its necessary to "warm up" the car before even leaving the driveway. According to the CarTalk guys, the engine really only needs 30 seconds to run before driving it.

I want to know at what engine temperature is it safe to drive a little more aggressively? Lets use 3000RPM as a benchmark, 3000 gives me a pretty good pickup. I know the Android "Torque" app defines operating temperature as 158F, and warns me if I exceed 3k when im below 158.

Thanks
 


IIRC our knock sensors come online at around 160* or so, so I would think that jumping in and dogging a completely cold motor would not be a great idea. I did this once leaving the house and had to get on it hard to avoid getting hit (driveway is kinda blind and someone came up quick, and the speed limit is 35 on my road) and in the process of doing so I heard it ping like a mofo. Just a GT, but still can't be good on it. If it's cold out I usually give it a minute or 2 to warm up and then head out. I've done this to all my cars and have yet to have an issue. Just my .02
 
I let mine warm up 10 min or a little more if below 0^F. About 5 min 0 to 32F and maybe 2 min in summer. I like a warm car in winter and maybe let it warm up too much. These aren't exact times just a guess. I generally take it easy for the first few miles of driving, especially in winter to warm up transmission oil.
 
Generally below freezing i let it warm until I have heat (engine temp 100-120) when its been sitting in the sun, the interior warms up nice (love having a black car), once i get much above 50 outside, i let it sit for a few seconds.

Madness- you made a good point about the transmission, that warms up much slower than the engine, and yes i do avoid reefing on it when its cold (and warm for that matter) During the summer when its 80+ I dont worry about it too much because it takes a long time for the trans to cool all the way down.

On the real cold days, I get all the way to work and the trans has not made it to 100 yet. IIRC one day the high was 3F, the trans got to 59F and that was it, of course work is only 3 miles away, and i did let it warm up.
 
Usually on warm days I just get in and go,but when its cold a 5 min warm up helps.Except my trans wasn't shifting into overdrive during the cold spell very well,so that made me raise an eye brow.Now since its been warm no problems with trans.
 


GP Guy- Are you sure it wasn't shifting into OD like it should? I know when it's stupid cold out my GT will shift into OD just fine, but it seems the TC will not lock until the trans warms up a bit. Then I notice the RPM's drop a little more and everything is fine. Seems normal to me.
 
FordMan77 said:
GP Guy- Are you sure it wasn't shifting into OD like it should? I know when it's stupid cold out my GT will shift into OD just fine, but it seems the TC will not lock until the trans warms up a bit. Then I notice the RPM's drop a little more and everything is fine. Seems normal to me.
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The way you described it is exactly the way it happens and I never paid attention to it before.Glad to know all is good and thanks for the info.
 
FordMan77 said:
IIRC our knock sensors come online at around 160* or so
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I have never had knock issues though. I track Knock Retard in Torque, and I dont get the slightest bit of knock, even on no-name 87 gasoline. When its less than 15F outside, my lifters tick for a few seconds but thats about it.
 
Great topic, bc most people really dont know whether to do it or not. Now your average technician today will tell you that newer cars really dont require it(bc thats all they're being taught now of days). Now a lot of old school mechanics will tell you that you probably dont have to either(most likely bc they dealt with carbuerated motors all their life and now are comfortable with fuel injected motors which dont nearly take as half the time to warm up).

Now this is what I would tell you "hot or cold weather, on COLD starts give your car at least 1-3 min of run time before driving it". For people that dont know they would ask why. Let me start with the most imp, Your oil temp. Not allowing your oil to reach operating temp could be critical especially if your motor is already high in miles. Coolant temp could be critical as well. These temps allow proper combustion, proper cooling, proper heating as well, proper distribution of lubrication, even the fuel has to be at a certain temp to work correctly and also to help burn off carbon deposits.

I could go on and on of why these operating temps are so important. Yeah, you have closed loop and open loop in which our cars could be operated in both but that doesnt mean you could go racing in open loop in the middle of the blistering cold weather. Now our cars work best in closed loop, hint...thats when most fluids are up to operating temperature. You strecth before you excercise, you dress up before you leave out the house, so treat your car the same way before you drive it.

Long idling is not good for your motor, but regardless of what anybody says...on cold starts allow your car to warm up for at least 1-3 min and of course it will reach full operating temp a few minutes after you drive off.

Later, Dee....
 


Dee23 said:
Long idling is not good for your motor
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I have heard many people say this, why is idling not good for the motor? There are plenty of fleet cars on the road that idle for extended periods every day such as police cars and taxis, and they still run 400,000+ miles.

Also, closed vs open loop, I believe that happens at about 80F on our engines, at least thats what ive heard here at GPF. Im not disputing anything youre saying, its good advice, Im just trying to understand how this stuff works.
 
Cold engines typically want a rich (more fuel) mixture to run well, with electronic fuel injection, if your car’s engine is cold, sensors relay that information to a computer, which signals the fuel injectors to stay open longer, allowing more fuel into the engine to help it run while cold. As the engine warms up, the computer signals the injectors to let in less fuel and everything returns to normal, the faster your engine warms up, the quicker it reaches its most efficient level of operation.

Letting your car sit and idle is the slowest way to bring it up to operating temperature because it’s sitting at just above idle speed, this method of warming up also invites other problems. Modern cars are equipped with a multitude of devices to help them run clean and efficiently, including a catalytic converter (sometimes three of them), an O2 sensor that works to oxidize unburned hydrocarbons and reduce carbon monoxide and nitrogen oxide levels in the exhaust stream. A cold engine emits higher percentage of unburned hydrocarbons and much higher carbon monoxide levels than a warm engine.

The average catalytic converter can’t process 100 percent of unburned hydrocarbons even in the best of times it needs high exhaust temperatures a minimum of 400 to 600 degrees Fahrenheit — just to start functioning. Because of the catalytic reaction, the higher the pollutant input, the higher the operating temperature of the catalytic converter after it starts working, typically about 1,200 to 1,600 degrees. Because a cold engine emits high levels of unburned hydrocarbons, it can cause the converter to run hotter than desired. If this occurs too often, these high temperatures can cause the converter to physically collapse internally, or plug. This doesn’t happen at once, but over time giving poor mileage and dirtier exhaust and can keep a car from running all together

Hope I helped, warming a car up was good to do in the old carburetor days with no EI (Electronic Ignition)


​
 
Logan-

I partially solved that problem. I noticed that the car was taking an inordinate amount of time to warm up, about 25 minutes to reach 195. Turns out the old thermostat was faulty. It was stamped 195 but at speed it would not go past 186. I thought perhaps it was a mismarked 180*. With the correct 195 in there, it idles for 10 minutes and i have good heat.

Sidebar: It that why the exhaust smells different when the car is cold? Its nearly undetectable at operating temp, but when I fire it up it smells like an old Chevy. (With the Buick motor, I guess it kinda is...)
 
Good info Logan...And ima add that any motor would rather be driven than idling. To clearify my lil theory a lil better, I let my motor run for 1-3 min on cold starts to simply to get my oil flowing the way it needs to(of course this 1-3 min helps reaching operating temp also) but getting that oil all over operating parts(gotta get that crankshaft lubricated real nice LOL) is my major concern bc the operating temp will come as you drive. Starting your car on cold starts(especially in the real cold mornings) and pulling right off immediately could fuucckk some shhiitt up and if not now, eventually. I've known a few people that this has happen to(particularly a Suburban that I remember) but you have to allow that oil to cycle a few times at least.

Theres times when our cars sit overnight, for days, and sometimes weeks depending on your situation so our motor/oil deserves a few cycles before we go beating on it or doing 75mph on the highway. Preventive maintenence is key to a car/motors life so add this to your preventive maintenence list and allow your car to have at least 1 minute to cycle things.

Dee...
 
I usually give it around 30 seconds on cold days (0*) and then drive nice and gentle untill i hit minimum 160*..... im tuned so i can see kr at 40* coolant temp. I never bother waiting for the trannie.... that takes like an hour to get to temp. Scanguage is your friend
 


I felt like Logan contradicted himself with the cat info. In the first couple of minutes, the cat isn't up to temp and can't run hotter to burn off the higher amounts of fuel, pretty sure it was said that it would. At least that's how I read it. ??

You don't want to beat on the car until the knock sensors are active. That's the only thing I follo.... wait, I'm a bad owner. :)

In reality you want the engine/trans up to normal operating temps before getting on it. Beyond that the engine/trans was designed to be started cold and driven nearly immediately. Is it ideal, I'd say that depends on the temps. If you live at the north pole, likely you want to give it a few seconds.

The reality is older motors didn't need to be warmed up to be driven, the motor typically woudln't run very well under load until it was warmed up. Many drivers didn't work a choke very well and therefore they didn't have the ability to drive reasonably w/o warming it up. Right, I had a manual choke, high mileage 350 that lived outside and even that could be driven if you knew how to drive it.
 
Ive gotten better about my warm up time with the remote start auto shutoff around 10 mins on my gxp. I like warmth at 4am omw to work, with the gtp when i had to walk out to start it in the morning itd run 20 mins or so. Really wish spring would get on track!
 
Yeah that scan gauge is one thing on my list that i havent managed to get. Im assuming the AeroForce would be the best, been looking for a used one but cant find one so I may have to cough the money up to ZZP or some vender that sells it
 
Thanks guys and I just want to claify some thing, I typcally start my car, then puton my seatbelt, check mirrors the slowly pull out of my drieway the road to the highway has a speed limit of 45mph which I do obey (because Barney is always hiding on it somewhere) and is 4 miles long, by the time I get there the temp guage is reading where it shouldbe then it is hit the hwy I would never jump on the car until temp gauge s at normmal Temp
 
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