Help!! Past 4 days nothing but gas engine use

Cold weather + short drives = more engine running and lower MPG.

For a couple weeks here it was pretty cold and I did nothing but short (<1mile) drives, and my MPG was down to ~38! Warmer temps and longer drives always help. If you have errands to do, drive to the farthest place first. If you're driving by yourself to some place that's reasonably close and you don't have to carry a lot, ride a bike and your fuel economy will improve

 

If you haven't read about the warm-up cycles, read this. It sounds like to me, that you are not getting to stage 4 like you used to.

 

The engine running is normal when it's cold out. *Don't* block the radiator unless you have some way (scangauge, etc.) to monitor engine temperature.

 

Two things, yes it runs more in cold weather like the others have said, and if you're taking short trips and trying to use the battery it could also be that your battery SOC is low, so it needs to recharge the battery, making it more likely to run the engine even when warm.

Which brings me to the second point - I'm not sure if I'm reading your post right, but you shouldn't be trying to use electric power exclusively. Electric power comes from the battery which comes from the regenerative brakes which comes from forward movement which comes from the gas engine. (The battery can also be charged from the generator directly from the engine, but it's not a lot better). Each step loses some efficiency, so it's more economical to use the gas engine directly for normal acceleration. Save the electric power for extending a glide with a warm engine or when heavier acceleration is needed. Your MPG will go up.

A recent trick I've read about and experimenting with a bit since my commute is so short, is to put the car in neutral whenever coasting during the first mile of driving. You can't recharge the battery while in neutral, so it's certainly not effective to use full-time, but the MPG does improve for the first 5-minute bar, which is about all I have on my commute. I'm still getting 45 mpg on this tank, but that includes occasional longer trips. Last year I was getting maybe 42 mpg in weather like this and that was on a longer commute. (My Prius lifetime average is 49.6 => 50's in the summer).

 

I think that's fine. It's only when the temperatures get into the 50's (Fahrenheit) that you need to monitor how much is being blocked, particularly on trips longer than a half hour. Read efusco's warning in that regard.

If it's below freezing, you should be able to block the whole thing safely. I block the top and 3/5ths the lower, and leave it for the winter. But then there's the risk of forgetting about it when it finally does warm up.

 

Yes, it's the cold affecting your mileage. Btw, 20 degrees is not even close to really cold. We go to the beach when it hits 20!

Tom

 

It could be in the cold batteries lose efficeiency.Bad idea blocking the radiator.

 

I think gaining a few MPGs while incurring some risk of burning the valves is a poor tradeoff. But that's just me :_>

 

block it all. your avatar is two cars buried in snow... its more than cold enough that you have practically, next to barely anything at all to be concerned with.

i block everything up to 50ºF...have been doing it for more than 2 years...

 

I went all last summer with everything but the bottom two slots stuffed with pipe insulation. According to the Scanguage, the temp never rose above 195F. Most of the cooling effects come from the lower slots in the grill.

By using nerfer's coast-in-neutral technique I have gotten 50 mpg for my first 5-minute bar on numerous occasions.

The colder it is, it seems that it takes less pedal pressure to kick in the engine on take off.

 

I run with the top blocked all year. I have one open "slot" in the bottom now. I have yet to hear the fan turn on and have the utmost confidence in Tony S., E. Fusco, and others. With the grill blocked this chilly month I now have 49.0mpg & 49.3mpg tanks which are below my 51.1mpg lifetime average. I don't expect the blocking to improve the lifetime average but I do expect to maintain it. I'll leave the temp set at 73 and turn the fan on low after 5 minutes or so to get heat from the left vent. The batteries aren't as efficient if they are too cold.

 

A lot of people are telling you to do it, one established person is recommending only doing it with a scangauge or CANview attached, and one unknown person (first post) is saying it's a bad idea but doesn't elaborate.
As long as you don't fully block or if you unblock when the temperature gets in the 40's and above, you have nothing to worry about. Assuming you don't make 5-mile uphill climbs with a heavily loaded car with the front wheels spinning in the snow. Then the engine could get pretty warm no matter the outside temperature.

 

Why is it a bad idea? Support your statement.
Numerous folks here block their grills with good results.
Why do you disagree?

 

+1.