Ok i just got into it with the stepdad. Here it is im at my family's house in a New England state and i go outside to start the car from being off and cold all day, its snowing out and ~25 degrees. I start up the 2003 GMC Envoy XL. I put the defrosters (rear electronic, set to front minus the vent for the feet) on almost right away, and rev the engine within the first 5 minutes a few times to ~3000RPM for maybe 10 seconds. Then i put it in drive, foot on the brake (under load for about 30 seconds, to help.) Within the 5 minutes the snow is melting and it is warmed up, whereas previous was sitting as an ice box on the snowy street.
Now, of course it is not my SUV so they come outside and say "you dont need to rev it up, it will warm up in the same amount of time." Now. I am thinking that, since i put the defrosters on right away, that it WONT warm up as fast. He is talking about a pre-set idle speed, and that "it would warm up the same."
Who is right here? Did i help it warm up? I can say that, from my experience with this SUV, i appear to have helped the warmup happen in half the time (blowing hot air from vents and melting the snow on the windows) with my "revving it up."
The videos are uploading now, of the 3000 RPM rev and the oil pressure going to just under 60 before falling back to 40psi. Who is right here?
Engines under load from a cold start
- Thread starter 45ACP
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OVERKILL
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Why would you rev it up so high at such a temperature? I'm sure 1500RPM would have been plenty.
Who's car is it? That person is right.
Personally I don't idle a car for five minutes and I don't see why it would get put in drive than then revved with the other foot on the brakes, but to each their own. I have a remote start that gets used about twice a year.
Wasted your time and not necessary at all. Fuel injection/computer management will put the idle where it needs to be for a decent warm up as it sits. In the grand scheme of things it may have made a miniscule difference in how fast it warmed up.
3000 rpms is not necessary at all on a modern fuel injected car on a cold startup.
Why people feel the need to let a car sit and idle for 5 minutes just to melt snow is beyond me. There is this neat device called a scraper and brush made for that.
i wouldnt even rev it...let alone 3000 rpms on an engine that probably redlines at 5-6k.
When it is cold my car engine puts its self into a high idle around 1400rpm. I just leave it at that and don't put the car into gear until it drops to the normal idle, which can be upwards of two minutes if it is below 0F, or about when I am done scraping frost off the windscreen.
Modern cars just don't need a lot of warm up time. Now I try not to rev the engine over 2000rpm until the engine is up to operating temp but that is just a personal preference.
OVERKILL
$100 Site Donor 2021
Originally Posted By: kb9skw
When it is cold my car engine puts its self into a high idle around 1400rpm. I just leave it at that and don't put the car into gear until it drops to the normal idle, which can be upwards of two minutes if it is below 0F, or about when I am done scraping frost off the windscreen.
Modern cars just don't need a lot of warm up time. Now I try not to rev the engine over 2000rpm until the engine is up to operating temp but that is just a personal preference.
Originally Posted By: OVERK1LL
Why would you rev it up so high at such a temperature? I'm sure 1500RPM would have been plenty.
OVERKILL
$100 Site Donor 2021
Well, you can be proud that you probably damaged his engine. I'm sure "that'll teach him".
And respected? You rev'd an engine that was at -25 to 3,000RPM. Rev'ing the poo out of somebody else's vehicle while it is cold is the wrong way to go about getting respect.
Originally Posted By: OVERK1LL
Well, you can be proud that you probably damaged his engine. I'm sure "that'll teach him".
And respected? You rev'd an engine that was at -25 to 3,000RPM. Rev'ing the poo out of somebody else's vehicle while it is cold is the wrong way to go about getting respect.
Originally Posted By: OVERK1LL
Why would you rev it up so high at such a temperature? I'm sure 1500RPM would have been plenty.
OVERKILL
$100 Site Donor 2021
Originally Posted By: 45ACP
Originally Posted By: OVERK1LL
Well, you can be proud that you probably damaged his engine. I'm sure "that'll teach him".
And respected? You rev'd an engine that was at -25 to 3,000RPM. Rev'ing the poo out of somebody else's vehicle while it is cold is the wrong way to go about getting respect.
Probably didn't hurt anything (and I read it as the temp was about 25 degrees). Did it warm it up faster? Sure, a little bit. Would I be torqued off if you did that to my car? Darn right I would be - that would be the last time you'd ever see the keys from me!
OP put a tilde in, it's "about 25 degrees (F)" not "minus 25'F".
Revving doesn't make much more heat as there isn't much more load on the engine. If he had a mechanical fan that would be something. If he ran all his electric stuff like the defroster and heated seats that would also put more load on the alternator and engine.
The computer triggers the coolant temp gauge, goosing the gas may have made a burp of warmer water pass the sensor. The effective output transistor resolution for the gauge isn't that great, maybe 6-bit or so, so if you break out the magnifying glass you might see it "tick" up.
If I can stand it, I like to drive in the snow without any heat at all. It keeps the snow from sticking to the windscreen and it just blows off in the wind without any wipers. If I get stuck in traffic I don't get a melt/ refreeze situation. Also I can reach down and pick up, off the floorboards, snow that fell off my boots, and my boots don't pick up new snow to track in the house... because they're cold!
I wouldn't go to my sister's in DFW and argue the best philosophy for sunshades, fans, and AC use. Nor would I complain about the weather (until, of course, I was back home. 
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If I can stand it, I like to drive in the snow without any heat at all. It keeps the snow from sticking to the windscreen and it just blows off in the wind without any wipers. If I get stuck in traffic I don't get a melt/ refreeze situation. Also I can reach down and pick up, off the floorboards, snow that fell off my boots, and my boots don't pick up new snow to track in the house... because they're cold!
I wouldn't go to my sister's in DFW and argue the best philosophy for sunshades, fans, and AC use. Nor would I complain about the weather (until, of course, I was back home. )If your goal was only to warm it up fast then you accomplished that. It will definitely warm up faster if revved.
Warming up faster is the problem though. It can cause metal to warp and crack. You also need to remember the oil is not up to temp so it won't flow as quickly to the bearings that are now being forced to spin faster.
This is also hard on the transmission. Putting it in gear and basically doing a brake stand with cold transmission fluid is an excellent way to burn up the torque converter or bands.
as for 3000 rpm in park with no load on the engine, i dont think it should be a regular practice but im sure it was fine. my Pontiac vibe's 1.8L revs to 2600 on its own when its super cold.
He said he was doing it to warm up the cab asap for a family member (who may be elderly or something) and if i was in that position i would do close to the same. its not like he could have built up oil pressure then driven slowly which is normally what people say to do to warm up. my jeep goes to normal idle RPM very quickly even when cold and at that point ill rev it a little to get it warm if im waiting for someone, otherwise i just drive slowly to get it warmed up.
I don't think it was a big deal under the circumstances.
Probably, the engine is fine. But I wouldn't do it. My cruze has a special high flow mode for the oil pump for cold starts, but even so, I wouldn't rev it too much. I agree, the ECM will idle where it needs to. In the case of my cruze that is usually about 1,500RPM for a few minutes, depending on how cold it is.
My explorer when really cold,the idle will jump to 2000rpm,and eventually it does settle down.Never had any issues,but I dont really like it either. 
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