Prius (Gen 3) :: Why Does Warming Up Use So Much Gas
Nov 15, 2012
I'm relatively new to owning a Prius (just over a month now) and am loving it so far. I've also been lurking these forums for a while and love reading over the technical explanations of how the Prius works and all that stuff. There something that I've been curious about recently
As we all know, unless it's already been running/warmed up recently the ICE has to start up around 7 seconds after turning on the ignition (unless in EV mode). When it does, fuel consumption figures go through the roof (10-15L/100km - which equates to around 20mpg) which is obviously very high.
Now, I leave my Prius in the underground garage of my apartment complex which is basically about 20 degrees celsius (70 fahrenheit) year round, which is pretty warm. So I'm curious about a few things:
1) Why the engine has to warm up when it is stored in a warm environment anyway (a regular ICE car doesn't need to warm up - you can turn it on a drive off).
2) Why fuel consumption is so high when the engine presumably isn't actually doing anything other than idling (or is it??)
3) To improve fuel consumption, would it be better to start off in EV mode, and only switch to normal/ECO when I know I'm actually going to need the ICE such as when I enter the actual roadway (so the engine is never in use when it is not actually powering the car)? I know fuel consumption will still be higher than normal as with any car when it is first started, but wouldn't this at least save it turning on unnecessarily?
4) If it is better to do this, why does it need to 'warm up' at all?
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I've had my PiP a month now. When ave temps were in the 30's EV range read 12.4 and I usually got an extra mile on my drives. With warming temps I was getting a read of 12.8 lately and 13.0 for the first time this morning. Thats with daytime temps of 60 but overnight it was still just upper 30's.
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Just got a new 2010 Prius III with 78,000 miles. I recently have had the car out when its been warming up outside and I noticed that when the AC is on every now and then it will make (in my opinion) a very loud electrical noise. I took it to the Toyota dealership and they said that the noise is normal (I even showed the person that checked my car in this exact video) however I question if they really heard the noise I was complaining about because it doesn't always do it (which is another reason I wonder if it isn't normal). Keep in mind my phone is close to the source of the noise so with the hood closed its not as loud but its still VERY noticeable.
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When I'm leaving the house and I pull out onto the street, I have to go close up a very annoying gate which takes a good few minutes to do. The car is still in it's warm up mode so the ICE is running the whole time. I know just turning it off would save gas, but would it be bad for the engine, to turn it off with the key before it shuts itself off?
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Basically, when driving shortly after turning on the car (when the engine is still warming up) I often experience a 'shot' of acceleration despite not further depressing the accelerator. In other words, I'll be driving along smoothly and suddenly the car will speed up slightly by itself without me having done anything. This only occurs when the HSI is past the middle (i.e. when the engine is powering the car) and when the car has recently been switched on. It's almost as if the sensor that detects my acceleration is re-calibrating itself while I'm driving, increasing the input to the engine.
The first time it happened it was a bit of a shock and I was a little scared, however I'm used to it by now and can anticipate it happening (however it doesn't happen 100% of the time). It's nothing too serious - it probably only accelerates a couple of KMs above what I'm actually doing but still is a bit of a worry. I'll be taking it in for a service shortly and seeing what they say about.
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I noticed that if I turn on the car and just drive with the AC on, depending on the outside temperature, the battery goes down to 2-3 bars from 6 bars within a mile a so. As it has been discussed in this forum extensively, the higher the battery charge swing, the lower the battery life. I noticed something yesterday, I warmed up the car till the engine stops with the AC on, and then the drive off. The battery stayed at 6 bars for all my commute and I believe this is healthy for the battery. Suggest/observe similar behavior or am I just burning gas for nothing. I have a scan gauge and definitely you get worse fuel economy for the first few miles if you warm up the car.
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I have purchased a 2010 III Prius with 73K miles last week after my 2006, everything is fine for me but I have a scary problem , the engine sound is very high while driving even after enough warming up, specially when the ECO meter reaches the PWR area or when accelerating hardly, I tried changing the engine oil with synthetic 0W-20 and the filter and the sound still the same.
Check the video attached and also note that
- Its winter here and temp is 50F.
- The car was imported from the US,
- The speed in the video in KM/h.
- I am using clean OCTANE 95 fuel.
- The video was after driving 20 Miles.
- I have latest version of Techstream with original Mongoose MFC...
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Last night during the East Coast's snow storm, I left my 2004 Prius warming for 10 minutes in park. I have a newborn and wanted the car warm for her. When I got back outside to leave, the Prius had died. The check engine light was on, but that was on before because I need to get the oil changed.
I went to jump start it, but when I opened the hood, I could hear that the engine seemed to still be running - it sounded like the belts were still going. So I was nervous to jump start it with the engine still seemingly on. I waited 30 minutes and that noise stopped.
When I tried to jump start it, I couldn't get the fuse box cover off after an hour of trying at 10PM, in the snow and rain. So I gave up and will try again later today.
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Car was working just fine. i changed the oil. after this, i have this problem:
Engine cold or go at freeway speeds = no problems
Engine hot and stop and go traffic = sometimes the engine will not rev above 1000rpm. when stepping on the gas, i will get a rough idle but engine would not go over 1000rpm.
I can shut off the car and wait some time, then the car will work again for a while.
No check engine light, no error codes, nothing .....
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A couple weeks ago, I noticed the a/c air warming up while I was in traffic. Later the car started overheating while the a/c was on in traffic, but cooled back to normal as the a/c was switched to econ. As of a few days ago my a/c air is not cold at all anymore, in traffic or moving. And now today, my car overheated in traffic without the a/c on, but returned to normal after I waited out the freeway blockage and drove home when the traffic speed was higher.
I've been reading threads on here for about three hours now and going out to run tests. It appears that neither fan runs on low or high speed. I want to check the fuses, but the fusecard is like reading hieroglyphics. It appears that slot 25 (with a picture of a fan) might be the right one, and after checking it appears intact. Questions:
- Is there a fan fuse? Is it #25? Are there more than one?
- If the fuses aren't the issue, is there something else to rule out before removing the fans for inspection and cleaning or replacement? (controller module, thermostat, relays, etc.?)
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91 Mirage starts and runs ok but usually will not start again after warming up. What are the possible causes and how do I check to eliminate dead end cures.
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Bought a 2011 Santa Fe in May. When I'm warming up the car, there is a banging or knocking sound coming from the passenger side wheel area (I think). The colder the outside temp, the louder the sound.
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I have a 2006 Audi A4 with about 90,000 miles on it. Recently, the engine has been making a clicking noise when it is warming up. Once the engine is warm it stops. No, performance problems, just the sound. It got an oil change recently (I always use synthetic oil), but the sound was occuring before and after the oil change. What it could be?
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I have an 03 civic which has recently exhibiting rather inconvenient power loss during warm up.
It seems to be worse when it's below 35 F out... The car starts just fine and I can generally drive several blocks just fine as well. Then for no apparent reason, the engine loses basically all power. It doesn't stall, but there is basically no power. When I pull over, the idle falls to ~400-500 RPM. Pumping the gas increases the RPM slightly, but again, there is no power.
Then as quickly as it began, the problem disappears; the engine returns to normal idle/power. This never reoccurs if the engine is kept warm. However, if the car sits for a few hours, the problem happens again. I would estimate the power loss occurs for ~30 seconds. The check engine light does not turn on before, during or after these episodes. It's almost like the choke is sticking.
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This is after a few minutes of the car warming up.. I'm concerned do to the fact that I've only owned the car for two weeks .
[URL] ...
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We have a 2005 toyota matrix with 152k miles. In the heat of the afternoon, or after driving 25-30 min the car begins to shutter. Slight hiccups when at speed, then stalls if idling, like at a stop light of the exit ramp. It starts right up, then dies when put in drive. We have taken it to toyota, TWICE. On the second trip, the car died on them and they still found nothing. The check engine light is not on. There are no fault codes. Toyota said replace the spark plugs, which I did. Still has same issue. The ECM was replaced under warranty a couple years ago.
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2004 Hyundai Accent has is misfiring, after warming up, only in idle. This only happens after about 30 seconds in idle. Could it not be getting enough gas? This being said I was getting misfire on 3 as well but that would happen all the time and cause the entire car to shake. This problem is now fixed and only #4 is causing me problems.
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2002 Jetta 1.8t, auto tranny, 90K miles. Recently took it in and had all coilpacks replaced under VW's recall.
Sometimes when it's been sitting out in cool air for a long time (in Texas summers, this is nights-only), about 3 miles in it suddenly starts misfiring- BAD. Check Engine light comes on. Lasts about 30 sec, then goes away and doesn't come back for the rest of the drive. WTF?? I can't make it happen on queue.
I heard about the all-too-common grounding problem on the engine harness. I did find a significant resistance between the ring terminal on the head and the battery (-). I tied the 3 ground posts under the battery together with 12ga wire and crimped terminals, and ran another 12 ga wire up to the engine block ground right under the ring terminal that grounds the coils, which should have shorted past any weak spot on the harness. PROBLEM STILL OCCURS!
Scans showed:
17766 Cylinder 2 Ignition Circuit: Open Circuit
16682 Cylinder 2 Misfire Detected
16684 Random/Multiple Cylinder Misfire Detected
17658 Low Fuel light (only ~3 miles after lighting the Low Fuel warning, I don't think the fuel pump's running dry just yet here)
Seems to focus on Coil 2. But last time I did this I got these errors for Coil 3 and swapped it for a new replacement I had in the trunk in case one went out unexpected. Well now it just says Cylinder 2. Just did it again tonight after clearing codes and got these same Cylinder 2 errors again.
Actually I started to wonder... I've been running the tank close to the "low fuel" light to check my actual mpg usage (no display for it in my MK IV), but fill back up a few miles after it lights. I can think of a couple of spots on the late-night drive back that I see this, one's after a hill which might cause a fuel pump to run dry temporarily, but another's a light downhill then up a light offramp. I don't think the tank's been low every time this happened but I'm not sure. Well, a couple of times it's been mostly level in the parking lot anyhow and misfired a bit right off the bat when starting, so probably not.
Wouldn't there be some sort of "low fuel pressure" code if fuel starvation was actually the issue going on? Hmm, I went looking and I'm not sure there is one for a MkIV, there's errors for fuel trim but I don't think you get those in short-term. This is kinda scary how it just goes out while driving, and I can't do much to reproduce it or test out fixes.
So looking further, other people report what may be intermittent fuel pump issues when the tank goes low. But could that result in "Cylinder 2 Ignition Circuit: Open Circuit"? I mean the coils will still electrically read as firing. Of course if the system gets all glitch-y, the software may be making a mistake somewhere and report this wrongly.
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My car has developed a strange engine/transmission shudder that occurs only between the temps of 32-50F. It happens when the car is still warming up, when I pull up to a red light and put my foot on the brake pedal the front end makes a vibrating/shuddering noise. You can only hear it from the inside, it sounds like something under the hood or maybe dash is vibrating.
If I shift into neutral or park it goes away. It looks like the RPM drops in drive, but it won't happen when the car is warmed up or if its colder (20F) or warmer out (50F). I recently installed a front strut bar, but I'm not sure it's responsible for causing the vibration I'm hearing.
I checked the oil level this morning, it's right at the full mark. I might try some injector cleaner but it's worth noting Hyundai recommends frequent spark plug replacement in these engines. I believe the manual states to change the spark plugs at 45K, more frequently if the car idles or is driven at slow speeds. I've also seen the 2011 manual indicate to change the plugs out at 22.5K.
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I have a 2006 Ford F-150 with a 5.4 liter engine. After it warms up past the operating temperature, it dies abruptly upon coming to a halt with no acceleration. The RPMs have to stay up to keep it running. No codes are registered.
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Every morning 1.8T idles high when warming up usually takes a minute or two to idle down. When your running late kind of annoying when I drive before idle goes down to normal brakes seem way to responsive and jerky...
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