Yeah se you talk about my inability to accept criticism and use the search button, but see, that's the thing, if you bothered to even read the original post, or any of my posts, you'd quickly see that neither of those are true. Now I drive it normally, just like anyone else on the road, I hear people talking about redlining it and being on it hard, and still returning 37mpg, I drive at most 20 miles in either direction on the highway, occasionally taking the back roads, and where ever I am going is right off the highway. Which has already been said. As well as the fact that I bought the car used, with 48k on it, now what used car has a break in period is beyond me. Your argument for the power band being different is only valid if you think i've only driven a 4.6 my whole life, which is just a joke. Now my lack of information is due to the fact that this is a ongoing problem that I am trying to correct, it's a gas mileage problem, it takes time to try new things, and see the results. Of course I don't have a vacuum leak, i check for those kinds of things when I buy a car. The plugs were one of my next thoughts, but as I said, this is a try and fail process, not just throw a bunch of things at it at once and hope it helps. The whole reason I started a new thread is because I searched and hadn't seen anything with this poor of gas mileage. Now everyone has been very helpful up until you decided to come in and start making assumptions without even reading. So please, if you don't have anything legitimate to add to this conversation, kindly leave, so my thread, that I started to seek help, doesn't get locked because of back and forth squabble.

 

Now I did have a thought today that had not crossed my mind, My battery was dead when I bought the car, not uncommon. They didn't have one on hand so they just gave me the 150 off. I didn't have any problems with it until 2 days ago, when it was just dead on startup. If auto zone is open tomorrow i'll have the battery checked, but could the alternator, even if it was running at double capacity to try to keep the battery charged, be responsible for this kind of loss?

 

There is multiple sweet spots and with out the right octane for the engine you will not find them. It has nothing to do with what Honda says about using 87. They say 87 or higher and its up to you to find what works. My experience tells me that premium is better than regular as far as mpg and power. You can have a new car that gets great mpg with regular and 15000 miles later you need premium. Some cars can run regular with no problems the whole cars life time but its very rare.

 

Then you didn't search very hard.

As you spend more time here, you'll notice it takes more than something this benign to to get a thread locked. Also, this is a public forum. We are allowed to chime in, just as you are.

This is a topic that has been beaten to death a hundred times over here. The outcome is always the same: habits change and mileage improves, or attitude gets worse when people help and they log off and don't come back.

 

If the voltage in the system is low, it affects everything, sometimes dramatically. It could cause your injector latency to go up significantly and in that case it could increase consumption. Hit the alternator output and a ground wire with a multimeter and see what it kicks out.

Load test the battery. Consider adding ground straps and a fat gauge fused charge wire of the alternator to the positive terminal to aid charging in the future.

 

Well seeing as how I still visit a forum for a car I haven't had in 4 years, I doubt that'll happen. But I hadn't seen my particular issue. I mean think about it this way, regardless of my driving habits, regardless of how I got to that speed, as I said I went on a short, about a hour and a half one way, road trip. Going 65-70, on flat highway, and only pulling 31. Something there, is off. And what I'm trying to say is the way I drive, yes I'm sure if I do learn the curve and all that it will help, but compared to what most people end up getting, without having to learn it, getting 25 is way too low.

Just look back in this thread, there are people who just bought a brand new one, that's not even past the break in period, getting 35mpg, they wouldn't have learned the curve any faster than I would have.

And the last 2 forums I have been on, were for mustangs (which have just been the worst) and a xterra, the xterra forum was so strict it'd get locked for anything, hell it could get locked at the mention of a old thread.

It's not like I jumped on here with a link to a ebay chip or turbonator asking how much it'd actually help. I'm trying to figure out what is wrong, because the gap, based on my driving style, is just to large for it to be something as simple as which gas I use.

 

See that was a thought I had, hell, 10 minutes ago when I woke up.

Hadn't occurred to me, but since the last 2 cars I had had larger engines, the parasitic drain from a dead battery is probably a lot greater on this car than those were.

Now here's my other question, I have yet to get the oil changed, i've just been to busy and don't feel like paying my shop to do something that can be done in 20 minutes. IF they put the wrong oil in it, could that affect it. and also should I perform any kind of motor flush if they did.

I inherited a civic a few years ago from a...lets just say negligent family member, and the oil hadn't been changed in 30k, took me about a week of engine cleaning/work before I even wanted to start it. Now i know it wouldn't have any real damaging affect, but is it something I should worry about in this little engine.

 

I don't disagree that your results thus far are atypical. As far as the learning curve goes, everyone is different. Tough to say who picks up what, and at what rate they will progress. I can appreciate your frustration.

25mpg is quite poor, I don't get less than 30mpg combined unless I spend a day at Road America.

Fortunately the mods/admins are quite tolerant here and it allows for a unique environment.

I would be very surprised if it came down to voltage. Maybe your O2 is dying. I would consider a scan tool or a pocket logger and see what the ECU has to say. The computer don't lie and it will cut diag time down considerably and save you from trial and error with pricey parts.

 

Dead/dying battery could make a bigger difference in a system like this. Basically you notice when one of the 10 hamsters under the hood dies.

The oil would have to be really quite thick or contaminated to drag that much on the motor. Like a 20w50, and even then I'm not sure it would be that dramatic.

In conjunction with bad fuel, cold weather, etc. those three factors could add up to a considerable amount of parasitic loss and drop in efficiency.

 

Still teaching huh?

 

I guess I should just bite the bullet and pick one up. And yes it's very frustrating, since I specifically bought the fit because everyone raved about their gas mileage, and it was the best used mpg in a hatchback. Also being that the car only has 48k on it, and it still being a honda, it's just harder for me to imagine what could be "dying" to cause this to happen. Along with not really having the car long enough to know if what I experience while driving is normal. As in i haven't become in tune with how the car feels to know if somethings wrong. eh, i ought to just say the hell with it and go buy parts for a k20 swap :P

but back to a real note, what worries me is that it's just a combination of things, because as you said, somethings off. I was really hoping the tires were the culprit, but now i get to do more extensive digging. Hopefully I'll have time tomorrow...well now today. MPG is always a crappy thing to diagnose, since I don't drive but a couple hundred miles a week, i have to wait a full week to see if anything I did matters. But i'll pick up a scan gauge tomorrow or over the weekend.

 

he must have edited his edit lol. What I was saying is that the old inherited civic, hadn't had it's oils changed, old story. Thing had a blow head gasket cracked radiator, hell someone had snapped off the wiper arm, thing was a mess. But what I was saying is if they had the wrong oil in it, would it benefit me to do a motor flush and then change the oil.

 

10 hamsters? being a little optimistic aren't we? lol.

 

vinny

It never ends... lol

What I don't give away for free, I am still doing for a damn good price. Obviously donations for the Compound Fit fund are always welcome, since the wastegates are so damn expensive. Otherwise there's only a little fab and electronics work left to be done.

I am probably going to disappear for at least a month in the spring when I finish the race car and go out for chassis cert and shakedowns.

 

DSM, try not to break anymore fishing poles while you're at it..lol!

 

Ya SG goes a long way in diagnosis.

K20 is overrated in the Fit, throws the balance off a bit. Not in general, I have seen 700whp+ K-series. But unless you're shooting for >500whp you don't NEED a K series. All the go fast bits exist to make a 450whp L-series. A couple exist. At least one of which is in the US.

 

See, something else I didn't know. But it was just jokingly, I didn't buy the fit to go fast, it's nice to throw around corners, which I missed, I went from a lowered rx8, to a lifted xterra on 33 inch mud tires. So being able to take turns again is a big plus.

 

That was a good trip. Up to my ears in keeper bass and pike!

Edit: I am not knocking the K-series Fits. they are badass little hatches.

 

Edit: I am not knocking the K-series Fits. they are badass little hatches.[/quote]

I agree 100%

 

I think the Fit's alternator is rated somewhere around 100amps (a lot for a little car). If it were pegged at this output, that's 1,200 watts (100A * 12V). 1,200 watts is equivalent to 1.6 HP. At steady speed, say 60mph the power required to maintain speed is maybe 15HP (a swag) so 1.6HP to run the alternator at 100amps would be a parasitic loss of 10%.

However, 1,200 watts will quickly cook the battery boiling off the electrolyte and causing a meltdown (ever see the China Syndrome?)*. If your battery isn't hot to the touch, I'd look elsewhere for the problem. Still, have the battery checked.

My personal favorite after tire air pressure is alignment.

Take an hour or two and reset your cars avg MPG display (zero trip miles) and take it for a nice post t-day cruise, say 40 miles out and back avoiding high speeds and steep inclines. You should be in the mid-high 30's. If not, there's definitely a problem. (check the alignment!)

Scanguages are nice and all, but if the car was not burning fuel efficiently, the check-engine light would be nagging you.

*kidding about the meltdown, after the electrolyte boils off the circuit is broken.

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