Would a malfunctioning O2 sensor affect MPG?

[dsteele713]

I purchased an insight with a faulty secondary sensor. I haven't done anything to improve MPG, and it is running non-OEM tires (175/60R14 Pirellis), but I'm getting less than 50MPG with fairly gentle driving, most of which is city.

I was planning on compiling a list of things I should do to improve MPG.

- Raise tire pressure to 43 Front / 40 Rear
- Replace Air Filter if it could use it
- Replace O2 sensor if it actually is affecting things

What else would you recommend? I'm surprised there isn't a sticky thread listing all of the things that can have a detrimental effect on mileage.

[AClewell]

The second O2 sensor won't effect your mpg. The number one thing to do is get the proper tires. Number two pump your tires up to at least the sidewall max pressure. I had some Futura tires on mine once, and had to run the sidewall max 52 psi to get my car to act like I wasn't driving in sand! Wow, what a difference thr RE92's make! I will never make that mistake again. I was young and uneducated in the ways of the Insight forums back then. I now run the RE92's over the sidewall max at at least 50 psi with no problems and much better mpg's! Also make sure you are running the proper 0w-20 motor oil by changing it with Honda or Mobil One 0W-20 and make sure you don't overfill it. It only holds 2.6 quarts! The air filter would be next on my list. Plan ahead on this one they can be a little hard to find.

[Balboa]

Originally Posted by dsteele713

I purchased an insight with a faulty secondary sensor. I haven't done anything to improve MPG, and it is running non-OEM tires (175/60R14 Pirellis), but I'm getting less than 50MPG with fairly gentle driving, most of which is city.

I was planning on compiling a list of things I should do to improve MPG.

- Raise tire pressure to 43 Front / 40 Rear
- Replace Air Filter if it could use it
- Replace O2 sensor if it actually is affecting things

What else would you recommend? I'm surprised there isn't a sticky thread listing all of the things that can have a detrimental effect on mileage.

Everybody here always tells me, tires tires tires! Must be RE92! Problem is a set of four will cost me $400 mounted and balanced unfortunately, so I'll just accept the 55mpg for now. I actually got it to 57mpg with a bit more highway driving. I did notice that one of my rear underbody panels are kind of dangling and bent weird, so that might be causing some wind resistance as well. Check your underbody.

You can't do too much as well if you live in a place with rolling hills that requires the use of assist. I know I'd be getting over 60mpg if I traveled on perfectly flat roads even with the aftermarket tires.

[Eli]

Secondary O2 shouldn't affect MPG. First will though.

Originally Posted by Balboa

Everybody here always tells me, tires tires tires! Must be RE92!

You can't do too much as well if you live in a place with rolling hills that requires the use of assist.

And there is a reason for this. Like I said, you haven't experienced the Insight as it was meant to be if you haven't felt what RE92s feel like.

When we bought Insight #2 it had some crappy 175mm tires on it. It felt like crap, just didn't want to roll. It still managed 64MPG on the 800 mile drive home, but that's in contrast to my 80MPG in Insight #1.

When we replaced the tires with the RE92s, even my fiancee commented that it felt like a totally different car, and she's not a car person. No longer was trying to keep the battery full a problem. It really changed everything about the car.. MPG, assist profile, regen profile, and just the overall feeling of the car.

As for the rolling hills.. the Insight actually does very well in rolling hills out on the highway. It's the next most perfect environment to completely flat. There is ample opportunity to regen; the key is avoiding the use of assist.. which can be hard to do if you have the wrong tires, lol.

[Willie Williford]

It all boils own to the "Nut on the steering wheel" for mileage or performance. Even with a turbo I can still manage decent mileage. The only thing I cant do is increase my LMPG. I would have to drive like a "granny" for many many many miles.
I think I am the only (original owner) Insighter that has reported a drop in LMPG, at 283,000 miles.

Willie

[AbCaRed00]

Just to note the indicated LMPG value can be reset [Owners Manual: pg.53. Gauges. ref'd] to reflect a new owners driving habits.
or inadvertently lost by incorrectly attempting resetting the Maint. Req'd light

If the LMPG has been reset, the newly indicated mileage could shift around even at high odometer readings until a pattern is established.

Pros and cons of resetting LMPG are seen discussed here.

[dsteele713]

Good to know. I'll check on the Air Filter and such and report back

[mynameissteve]

Originally Posted by AClewell

It only holds 2.6 quarts!

Interesting. I called my Honda dealership and they told me it holds 3.2 quarts.

[AClewell]

Your dealership is mistaken. It holds 2.6 quarts of oil with filter. I have been changing oil on this car for 11 years. You can put 3.2 quarts in if you want but it will be way over full.

[mynameissteve]

Just to be clear, I did not call them because I thought you were wrong or anything like that, I was just saying I at one point in time (about 1.5 years ago now) had that question and that was the answer I got. I always find it interesting when user anything has such a large difference from manufacturer specifications.