2 Questions; both Subarus

General Discussion
1

  1. My husband’s 2013 Impreza has been getting rather poor mileage. It used to get around 29-31 mpg, now it’s down around 23. The weather here in IN is getting colder, down around and below freezing, and we’ve been using Marathon gas, among others. Any ideas as to what could be going on?

  2. Nothing wrong with my 2019 Crosstrek, but I notice that the RPMs when I first start the car are often above 2K, which then drops below 2 as I drive along. Is this because of the engine warming up?

2
  1. Yes to the cold weather and possible driving pattern changes .
  2. You have a warranty so use it and ask the dealer but I think you are looking for problem that does not exist.

I guess you had to buy a different color that you previously wanted ?

3
  1. This is likely the result of cold winter temps, but it is also possible that the cooling system thermostat is “stuck” in the open position, thereby causing the engine to take longer to get to its proper operating temperature.
  2. Is this Crosstrek your first car? I have to ask that question simply because it is completely normal–for cars of all makes–to run at a higher idle speed until warm-up.

Here is a little tip, however:
If you lightly “blip” the accelerator before you pull out of the garage, the idle speed will drop by a few hundred RPMs. It will still be higher than when the engine is fully warmed-up, but if the high idle speed bothers you, this will lower the speed to a small extent.

3 Likes
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Is your tire pressure correct? If you haven’t added air to compensate for the drop in temperature over the past few months, it could be quite low.

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I don’t see any problems here . . .

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I bought red. Content.

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Yes, actually, we are always checking tire pressure, good thought though.

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For the Imprezza, there are a lot of things that could cause the drop in fuel mileage. A different brand of tire or winter tires can lower the mpgs. Id, check for stuck brakes, sometimes the caliper pins stick as they get older and hold the outer pad against the rotor.

Could be time for new spark plugs. You could have a leaky injector. The thermostat or the temp sensor could be off causing the engine to think it is cold. I have also found that the CVT is very reluctant to shift into the highest range when the air temperature is below 45 degrees F, it will remain in around the 5th gear range until the engine and ATF in the transmission is fully warmed up and that can take awhile.

I would check the transmission as well by driving it for at least 10 minutes and then getting out on the highway, on a flat section going 60 mph, the tachometer should be very close to 1800 rpm. If it is running around 2000+, it is not getting into its highest range. If unsure, put it in manual and shift up until the 6 appears and check the rpms then.

About the Crosstrek, yes that is normal and blipping the throttle won’t make it go down either. It is fuel injected, that works on carbureted engines. It goes down on its own as the engine warms up. By the time the blue light goes out, it should idle around 750 or so.

1 Like
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Very useful info, thanks much!

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It also works on fuel-injected engines, or at least it has always worked on my three fuel-injected Subarus. A light “blip” of the gas pedal brings the idle speed down slightly, and then upon being fully warmed-up, it goes down to its normal idle speed.

*Just to clarify, yesterday I tried this with my friend’s Rav-4, and it didn’t bring down the idle speed. So, while this trick clearly does work on Subarus, it may not work on all other makes.

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The computer injects more gasoline when the coolant temperature is cold. The effect of cold weather on average mpg depends on how long your typical drive is. If you drove 8 hours on the freeway the mpg reduction would be considerably less than if you drove short 15 minutes trips. The coolant is cold a higher % of the time on short trips, especially true when the ambient temperature is low.

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Thanks-- I will make sure hubby gets this info.

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Doesn’t work on my 2014 Legacy 2.5

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Well, it works on my 2011 Outback 3.6R, and it also worked on my '02 3.0, and my '97 2.5.

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It work’s with my 90 F150

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Works on my Lincolns and Sonoma truck.

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I’m sure you are all waiting breathlessly to know whether my Crosstrek responds to this. It doesn’t. :grin:

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crosstek idles at 2k at start? and lowers as you drive along? after 3 min, when you are stopped, what is idle? how about 15 min? i dont own a subbie but if it above 1k after 15min then i would be surprised