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Honda Accord Fuel and Fuel System Questions



  • elroy5elroy5 Posts: 3,741
    "The Accord V-6 ratings assume regular-grade fuel, and Honda will market it as a regular-fuel engine. But — pssst — it's good for another 10 hp and 10-plus lbs.-ft. on premium, acknowledges V-6 engineer Asaki."

    I've heard this. But I have also heard that it will take a couple of tanks for the computer to adjust to premium gas. And if you burn just one tank of regular gas, you are back to square one. So if you want to run premium fuel (for the power gain) you have to continue using premium all the time. I'll stick with regular, 240 horses are enough for me.
  • ray_h1ray_h1 Posts: 1,134
    No offense to you personally intended, but in my opinion Honda engineer Asaki's old wife would be better advised getting her tail in the kitchen to prepare a light repast of saki and sushi for honorable husband-san after a hard day at the test track. I'm also skeptical about a whole ten hp. - more likely on the order of about half that where the rubber meets the asphalt unless intake and exhaust modifications are undertaken for improved inflow and extraction at speed. I'll also disagree with my buddy elroy5 on a minor point. Nearly instant information from the knock sensors will allow the ECM to advance or retard ignition timing within two crankshaft revolutions to adjust for a change in pumped fuel octane - and the little buggers continue doing so on the fly whenever the engine's operating. (Knock sensors - the greatest advance in engine control technology since sliced bread and trade whiskey. ;))
  • ezshift5ezshift5 Posts: 852 whiskey

    ....sounds good (if unfamiliar). How would it taste - - compared to - - say.........Crown Royal?

    ..our northern neighbors may have competition....

  • "No offense to you personally intended, but in my opinion Honda engineer Asaki's old wife would be better advised getting her tail in the kitchen to prepare a light repast of saki and sushi for honorable husband-san after a hard day at the test track."

    Certainly no offense taken at all.


    1. In a case of choosing to believe a Honda engineer being quoted in a national newspaper over some random dude on some car forum? I don't know about you, but I'll believe the Honda engineer.

    2. That said, 5 HP, 10 HP, whatever. Neither one is anything to brag about, and neither one is going to be noticeable in every day driving. Me? I use regular in my V-6.

    3. I was just pointing out that this "mythical" 10 HP that, whether you choose to believe it or not, does have a real Honda source and is not, in fact, something someone just made up like some people on here would lead you to believe.
  • ray_h1ray_h1 Posts: 1,134
    Your points duly noted for future reference, fanshawe23.
  • nrborodnrborod Posts: 79
    I have an Accord 4cyl, EX-L auto and I've been advised that using premium is a waste of money. I tried it and didn't notice any diff. Why do it?
  • Exactly, why do it?

  • ray_h1ray_h1 Posts: 1,134
    )) "I have an Accord 4cyl, EX-L auto and I've been advised that using premium is a waste of money. I tried it and didn't notice any diff. Why do it?" ((

    Because an alleged Honda engineer quoted in a mass distribution national daily periodical of less than Pulitzer prize reporting quality said so. (Of course I'm only "some random dude on some car forum" {post #48} with consistently suspect credibility, so what do I know?... ;))
  • patpat Posts: 10,421
    The article ray_h1 referenced is linked in this post: fanshawe23, "Accord - Premium gas?" #44, 27 Oct 2006 8:44 am
  • blufz1blufz1 Posts: 2,045
    There was a test by a car mag a few years ago re regular vs premium and they found no meaningful difference in power and mpg. Shell claims to use more detergents so I usually run it. Try different brands and compare mpg to see if your car seems to have a preference. Ethanol reduces your mpg up to 10% so if I'm on the road,out of town,where ethanol is not required I buy there.
  • ray_h1ray_h1 Posts: 1,134
    California converted to gasahol January 1, 2003. I track my mileage and noted a mileage reduction from 32 mpg to 31.5. Four years later I'm still hovering between 30.5 mpg and 31.75 mpg. Taking the worst case calculation, I've only found a 4.69% reduction using recent mileage figures (30.5 mpg) with gasahol, compared to the best mileage (32 mpg) obtained with straight unleaded gasoline. I tried one tank of 91 octane unleaded premium and noted no perceptible seat-of-the-pants difference in power, nor any difference in tracked fuel economy. The only difference I did note with a full fill of unleaded premium was that my wallet was about $3.43 lighter for my effort. I've since only used 87 octane unleaded regular. Good enough means good enough. Alcohol has one particular property that's generally misunderstood but advantageous. It's miscible with both gasoline and water. Water, in the form of condensation from air (and air replaces gasoline in the tank as the gasoline is used ;)) will accumulate in the bottom the the tank. Predictably, it can accumulate to a substantial amount over time. The ethanol in gasahol will gradually and continually absorb and move this water accumulation out of the tank, through the engine during the combustion cycle, and out the exhaust pipe as steam. Once the vehicle's gas tank is rid of water, continued use of gasahol will prevent its recurrence. I suspect, but can't prove, that most reports of poor performance with gasahol are due more to the impact of initially moving water out of the fuel system than any inherent combustion problem with gasahol.
  • blufz1blufz1 Posts: 2,045
    Thanks for the info. My 02 V6 also seems to lose about 5% w gasahol. Never tried the premium in my auto. I run premium in my bass boat and yard tools for the extra detergents the premium claims to have. I run the gasahol only when I have to so that would seem to lend credence to your theory.
  • th83th83 Posts: 164
    Although there is no dyno evidence to back up the claim, I believe it makes a difference.

    I've been putting 93 octane in my 2007 Accord V6 for nearly 3k miles now, with only two tanks of regular: the original tank-full, and a full tank somewhere around the 2k mile mark. To be honest I couldn't really tell a difference for the first several tanks. In fact, when I first switched to 93 from 87, the car felt slower. That was likely due to the engine burning 93 octane using an ignition timing map optimized for 87 octane. However, after a couple of tank-fulls of 93, the car started to perk up a bit. Uncertain as to whether the added perk was due to the premium gas, the engine loosening up from break-in, or both, I decided to fill up with 87 and see what'd happen. I noticed a difference within half a mile of leaving the gas station. The difference wasn't startling, but it was definitely noticeable, and it became even more noticeable in stop and go traffic on the way to work the next day. The car just wouldn't respond as quickly as I'd come to expect of it. Throttle response was laggy and torque was missing throughout the powerband. Not only that, but my gas mileage for that tank was only 22 MPG, 2 MPG lower than the previous tank. While I'm sure the drop in mileage didn't have anything to do with the fuel itself, it was likely due to me having to put my foot deeper into the throttle to make up for the lack of power. After emptying that tank of 87, I swore that I'd only use 93 from there on out. I don't mind paying an extra $3 a tank if it gives me the responsiveness that I want out of my engine.

    I can understand why people don't believe that premium fuel increases the amount of power produced by these engines. It boils down to this: People are impatient and want instant gratification. In this case, they fill their Accord V6 up with premium fuel expecting instant results, and then, when they're two-tenths of a mile down the road and they can't feel an improvement, they immediately declare premium gas not worth it and let the world know they're not happy (and these people love message boards). Unfortunately, they're not willing to wait a tank or two to see what happens.

    Now about the waiting...

    From what I've read around the net, it takes at least 300 miles for the PCM to advance the ignition timing after the owner switches to premium gas. I've read that this is a safety measure that protects the engine from detonation in the case of a bad tank of gas.

    In other words, when regular fuel is used, the engine runs a "safety map", or an ignition timing map that is safely optimized for regular gas.

    Supposedly, this "safety map" is used for 300 or so miles before the PCM tests the waters again by advancing the ignition timing. If it immediately detects knock, the ignition timing will once again revert back to the safety map. However, if no knock is detected initially, the PCM will continue to advance the ignition timing until knock is detected. It will then dial back the timing a few steps to provide a safety net. This process tailors the engine's performance according to the grade of fuel used.

    Unfortunately, we'll never know for sure if this myth of extra power from premium gas is confirmed or busted as long as Accord owners refuse to have their cars dyno-tested. A couple of dyno runs would have this debate settled in an instant. All it'd take is for one person to go dyno their 2003+ Accord V6; one set of runs on premium fuel, and one set of runs on regular. I'd do it myself, but there are no shops in my area with dynos open to the public. The last one closed down months before I even got my new Accord. Unfortunately, I live in North Carolina, and not California, where there's a tuner shop conveniently located on every corner.


    Until the day an Accord owner steps up to the plate and solves this problem once and for all, this will always be a subjective debate...
  • elroy5elroy5 Posts: 3,741
    I tried to say this earlier in this thread, and met with some resistance from other posters, (claiming the engine computer would immediately adjust for the premium). I had heard from Honda techs that it would take a few tanks to get the extra power. I also heard that one tank of regular would put you back at square one. It would be nice if someone would prove this one way or the other.
  • blufz1blufz1 Posts: 2,045
    A car mag tested prem vs. reg in a honda a few years ago and found there was no appreciable difference in pwr and mpg fyi. Having said that, I do think your info is interesting. I might try a tank or two for fun to see. You may be getting a cleaning effect of the extra detergents in the premium.
  • elroy5elroy5 Posts: 3,741
    What mag did this test? I would like some details. Not that I would switch to premium, in any case. But I have heard from good sources that premium will improve power.
  • blufz1blufz1 Posts: 2,045
    Sorry, I take a lot of mags and this was a few years ago. Motorcycle users have also tested and concluded that regular produces the same hp as premium. Hope this helps.
  • robr2robr2 BostonPosts: 7,601
    IIRC it was Car and Driver. It was about 3-4 years ago.

    The only way to really see if using premium has any benefit is to dyno the vehicle under laboratory conditions.

    Seat of pants dyno can be wrong - especially if one wants to believe one way or another.
  • bf109acebf109ace Posts: 77
    Correct me if I'm wrong. I read the 2006 Accord 4-cyclinder 2.4L has a 15.40 Gallon fule tank. What's the reserve (in term of gallon)in the tank that will not be usable before the engine stops running? Will I be able to use up all 15.4 gallon?

    My experience has been that when I used up 12.50 gallon, the Empty Tank Warning Light is on. In one occation, I drove another 40 miles after the light was on. Then, when I filled up the tank I could only pump in 13.56 gallon.

    How much fuel (in gallons) is left when the warning light is turned on? Techically, will I be able to use up all 15.4 gallons. If so, will it do harm to the fuel system (i.e. deposit at bottome of tank will be sucked in the fuel system)?

    I don't intend to use up all 15.4 gallons but it's good to know what the bottom line is.

    Please share your experience. Any adice? Thanks.

  • blufz1blufz1 Posts: 2,045
    I think they have been 17.1 from 98 forward. The most I have put into my 2002 is 16.6.
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