Honda Accord Fuel and Fuel System Questions

)) "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?...

)

#53 of 89 Re: Premium gas? [nrborod] by pat

Jan 12, 2007 (5:30 am)

Replying to: nrborod (Jan 10, 2007 10:20 am)

The article ray_h1 referenced is linked in this post: fanshawe23, "Accord - Premium gas?" #44, 27 Oct 2006 8:44 am

Replies to this message:

blufz1 (Jan 17, 2007 12:30 am)
- ray_h1 (Jan 17, 2007 9:32 am)
  - blufz1 (Jan 17, 2007 1:54 pm)

#54 of 89 Re: Premium gas? [pat] by blufz1

Jan 17, 2007 (12:30 am)

Replying to: pat (Jan 12, 2007 5:30 am)

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.

Replies to this message:

ray_h1 (Jan 17, 2007 9:32 am)
- blufz1 (Jan 17, 2007 1:54 pm)

#55 of 89 Re: Premium gas? [blufz1] by ray_h1

Jan 17, 2007 (9:32 am)

Replying to: blufz1 (Jan 17, 2007 12:30 am)

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.

Replies to this message:

blufz1 (Jan 17, 2007 1:54 pm)

#56 of 89 Re: Premium gas? [ray_h1] by blufz1

Jan 17, 2007 (1:54 pm)

Replying to: ray_h1 (Jan 17, 2007 9:32 am)

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.

#57 of 89 Premium fuel in the 2003+ Accord V6... by th83

Jan 20, 2007 (1:25 am)

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.

*sigh*

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...

Replies to this message:

elroy5 (Jan 21, 2007 12:05 am)
blufz1 (Jan 21, 2007 12:28 pm)
- elroy5 (Jan 21, 2007 2:24 pm)
  - blufz1 (Jan 22, 2007 12:55 am)
  - robr2 (Jan 22, 2007 12:32 pm)

#58 of 89 Re: Premium fuel in the 2003+ Accord V6... [th83] by elroy5

Jan 21, 2007 (12:05 am)

Replying to: th83 (Jan 20, 2007 1:25 am)

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.

#59 of 89 Re: Premium fuel in the 2003+ Accord V6... [th83] by blufz1

Jan 21, 2007 (12:28 pm)

Replying to: th83 (Jan 20, 2007 1:25 am)

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.

Replies to this message:

elroy5 (Jan 21, 2007 2:24 pm)
- blufz1 (Jan 22, 2007 12:55 am)
- robr2 (Jan 22, 2007 12:32 pm)

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