Bad Gas Km-rage.

"AdverseMartyr" (ewilliamson) 08/24/2019 at 06:39 • Filed to: None

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Ok, not really rage, but a 2nd Gen Honda Fit G that is averaging 8kpl ( according to the computer) is not good. The range indicator thinks I should get around 500km on a tank, and I think the actual i s somewhere below 250 as well.

Since we were gone for two months it has taken me until now to put a few tanks of gas through the (new to us) car to be certain. So today I started trying to eliminate culprits. Since a new air filter is easy, and this was the old one:

(That’s after vacuuming a bunch of debris off it); I replaced the air filter. 2800¥ isn’t exactly cheap though.

I also picked up a 299¥ fuel system treatment to see if it will help when I fill up tomorrow.

Next weekend if I have time I will consider pulling the plugs since it is at 111K km ( Though from what I’ve read the plugs should be good for 100K miles).

Looking around the engine though, I start to wonder how worthwhile a cold air intake would be...

pip bip - choose Corrour > AdverseMartyr 08/24/2019 at 07:03

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do the spark plugs.

air filter was clearly a part of the problem

Snuze: Needs another Swede > AdverseMartyr 08/24/2019 at 07:30

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Another culprit is often the PCV valve. That should be a relatively cheap and easy fix.

ETA: do a little homework on Fit spark plugs.  As I recall they are indexed, meaning the gap has to point a certain way in the cylinder.

SiennaMan > AdverseMartyr 08/24/2019 at 08:20

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Yeah, according to the sites I have access to you should be able to get 11-14 kpl from a Fit (28-32 mpg, assuming the engine isn’t different from NA market models). Given that the air filter looked like that, you did change the oil and filter already, right? From my admittedly limited knowledge, the plugs sound like a relatively easy and with knowledge & tools cheap next step. (Unless I’m mistaken it looks like I could buy plugs for this online for less than 25 usd..)

AdverseMartyr > SiennaMan 08/24/2019 at 08:33

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I haven’t, but that’s because the oil looked very clean when I checked it.
The only thing is that from what I’ve read the easiest way to get to the plugs is to take off a decent amount of stuff directly above them (wipers, the metal plate there, and a couple other things). From what I’ve read it takes about 20 minutes or so, which isn’t long, but yet it is in Okinawa sun and heat.  

Captain of the Enterprise > AdverseMartyr 08/24/2019 at 08:37

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On my cars I got some improvement from all new air filters and spark plugs. My cars both had 121,000 miles on them when I got them. I got a couple extra  mpg I think after that. I also run full synthetic oil. 

Dogsatemypants > AdverseMartyr 08/24/2019 at 09:05

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You can use 0w20 or 0w16 to decrease internal friction and possibly boost mileage. The culprit was likely your air filter.

You nay want to try using some foaming intake cleaner to help scrub your throttle of carbon buildup. Check tire pressure too. Also try cleaning your mass airflow sensor.

If you do it right and can find a good spot outside the engine bay to route it, or modify the existing air baffling to isolate it fro. The rest of the bay, a cold air intake can help, if the ecu can accommodate the additional air flow.

someoneatacura > Captain of the Enterprise 08/24/2019 at 12:46

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If the plugs are iridium they’re good for around 160,000kms. Platinums are 110-120k, and copper is around 48k.

For fuel economy, always start with anything that causes drag. Tires and alignment are the biggest factors. Try running the tires 3-5 psi more than recommended. Check the alignment as well, it should be checked every time you get a new car, and once a year after that (unless you hit a lot of potholes, then I would do it more often).

Then after that you do the basics, like keep the car light, Practice  proper driving (easy starts, lots of following space, etc).

wafflesnfalafel > AdverseMartyr 08/24/2019 at 16:33

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dang - that could be the original air filter... changing that alone will probably provide the biggest improvement.

AdverseMartyr > wafflesnfalafel 08/24/2019 at 19:32

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Supposedly it was changed 2 years ago, according to the sticker on the airbox. I just don’t know what kind of air it had been sucking in.

gmporschenut also a fan of hondas > AdverseMartyr 08/24/2019 at 21:27

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I second Mass airflow sensor. when mine started going on my old car, miliage went to shit.

Random other thought, has the transmission fluid ever been changed? 

AdverseMartyr > someoneatacura 08/25/2019 at 02:55

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So with getting a new car and taking along trip soon afterwards, I didn’t move the tire gauge to Fit, and just did that now. So it turns out the front tires are well below the correct psi (27 psi is where they are at now.) So I’ll be fixing that tomorrow when I fill up.
Proper driving doesn’t really suit me; so I don’t expect miracles. ( Easy starts I mean, not proper following distances.)

AdverseMartyr > gmporschenut also a fan of hondas 08/25/2019 at 02:58

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I’m probably going to clean it if I don’t see any change from the air filter, or correcting the tire pressure (really a bit funny/sad that I never thought to move the tire gauge down to the new car after taking it out of the old car.)

someoneatacura > AdverseMartyr 08/25/2019 at 19:44

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Proper following distance means you don’t have to accelerate as much during merges. If make a big difference for fuel economy, especially when you gear down (fuel injectors shut off when the wheels are spinning the crank).

AdverseMartyr > someoneatacura 08/26/2019 at 05:07

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Yeah, that’s why I clarified that I meant easy starts don’t suit me. I enjoy having room to accelerate and get up to speed while having room to slow down or maneuver if needed.