Gas, am I nuts?

[HyundaiGuy]

Hi All,

I've been working with an odd gas mileage issue with my car. I noticed my gas mileage had dropped off and I couldn't figure it out. I did look through my service records and discovered that the dealership didn't change the spark plugs as recommended by Hyundai at the 30,000 mile service. At 35,XXX, I replaced the original Champion copper plugs with NGK Iriduim IX plugs. The original plugs didn't look all that bad.

The gas mileage didn't get better. I looked on line and saw many complaints of low gas mileage with the Accent, I didn't think I had a major issue as the car had always delivered 32-33 MPG highway. I was down to 28-30. My worst tank ever was 26. Not good. The car still runs fine.

One day, I was near my office, and fueled at the BP station near my office, about 40 miles from home. I had always avoided that station because their price is 10 cents a gallon higher that at home. That tank was the best I've ever done with this car- 34 MPG.

I realize there are many variables in fuel economy, but if I fuel at the Marathon closest to home, fuel economy is bad. The BP by the office is best. I tried a Sunoco in the mix as well and got 32 MPG.

I thought all of the fuel in this area came from the port in Tampa. Is there really that much of a difference in regular unleaded? Another question- this car has always been predictable as far as fuel economy, why is is being picky all of a sudden? I don't think it is a difference between summer and winter blends. Also, all of our fuel here is marked as "up to" 10% ethanol.

Edited for spelling.

 

[beast3300]

The difference in fuel comes from how well the operator keeps their station and also the additives added to the fuel. I never buy gas from a run down gas station for example. I also only use Shell because it is Top Tier labeled.

 

[Turk]

Lots of factors, keep repeating the experiment to prove it out.

I get better MPG's with BP also.

The worst MPG's are with Holiday "Blue Planet" gas. That screams a higher Ethanol %... I won't touch it anymore.

- Could be less Ethanol % in the BP gas.

- Could be the "Invigorate" additive in their gas.

 

[Clevy]

I read quite alot on this site and other sites about fuel. Many people insist it all comes from the same place and each brand just adds their cocktail of additives and that's it. Well from my own personal experience in my 2000 mustang with various upgrades and a custom dyno tune I would get anywhere from 18-26 mpg depending on where I bought it. So with such a discrepancy I decided to start testing gasoline.
My commute is 110 kms round trip, all highway,at 110 km/hr cruise controlled. I live in Saskatchewan on the bald prairie with no hills,wind is the only variable. Here our premium isn't ethanol polluted and I need it for the advanced timing in the dyno tune. Shell v-power would net me 26 mpg which is unheard of to me but I can get that repeatedly from this car. Esso was 18 mpg. I was surprised with co-op gas,I got 24 mpg with it.
When in British Colombia,chevron premium makes my car a beast,feels like more power but fuel economy isn't really measureable due to the mountains.
So from my experience here gas isn't the same. It might be when it leaves the refinery however something happens to it once other hands get to it,whether its the dealers,retailers,wherever their stocks are stored. I dunno but my car does.
Your results may vary

 

[Propflux01]

Are you sure it's not because of "winter gas" (Yes, I see your in FL, but wouldn't surprise me if FL got the same treatment other states get), or is it something you notice year round?

 

[HyundaiGuy]

Originally Posted By: Tim H.
Are you sure it's not because of "winter gas" (Yes, I see your in FL, but wouldn't surprise me if FL got the same treatment other states get), or is it something you notice year round?


We do have winter blend gas here, but this has gone on for the past 3 months, so I was definitely using summer blend then. I didn't make the gas connection until I fueled at the Marathon and that tank retuned 26 MPG. I had been using Shell or Citgo mostly.

On the first tank after the Marathon tank that returned 26 MPG, I bought the first tank of BP (as I didn't trust that I has enough fuel to get home as I should have.) That tank returned 34 MPG. I figured a swing of 8 MPG was too much, so I have repeated it a few times, an the BP is always great, and Marathon is bad.

So I am figuring my issue is definitely fuel related. I actually still don't believe there is that much of difference in fuels, but the numbers tell me otherwise. I am still puzzled why this issue popped up at 35,000 miles.

An idea- Hyundai recommends replacement of the fuel filter at 52,500 miles. Could the ethanol in the fuel have gummed things up? The fuel filter in this car looks to be a real pain to replace. It is actually mounted to the inlet of the fuel pump as an integral part of the fuel pump. Replacement of the filter requires partial disassembly of the pump.

Also, I have tried a fuel treatment (Chevron with Techron) as recommended by Hyundai in a TSB. There was no difference.

Except for the difference in fuel economy that I can measure, I feel no difference in the way the car performs.

 

[91344George]

I would bet that this is due to a change in the gas formulation, the refiners start to change over to winter blend as early as mid August so it is very possible that you are experiencing winter blend gas which is less efficient when it comes to MPGs. My Dad also noticed this with his late model Ford as well over the past couple of months or so.

 

[Donald]

The basic gas is the same but the alcohol and additives are added at the terminal. I think as someone suggested we are seeing varying amounts of alcohol.

 

[Quest]

I get avg 10 ~20% less fuel economy with E10 during winter time, mainly due to a lot more cold starts and city driving.

Granted that your Accent is on platinum plugs, why change it out @ such short interval?

Q.

 

[earlyre]

why did you change plug types? if I've done my research correctly, that engine was designed for copper plugs(hence they installed them @ the factory). copper is a better conductor, produces a stronger spark, and burns hotter; which again, this engine was designed for. you sure you are getting full combustion? could that be where your lost mpg comes from?

also the coppers are a good deal cheaper, and are pretty darn easy to change.

my independent research has shown a definite difference in brands of gas. my old car, ('00 Sonata, 2.4l cyl.)seemed to run better on gas from flying J truck stops (Which other family members have referred to as Junk ) go figure.

 

[Clevy]

Winter gas no longer applies since ethanol was introduced to the fuel. Here in Canada anyways. I don't understand why you would need fuel line anti-freeze anymore now that it's mandated at 10%. Before ethanol was mandated they would use,guess what,ethanol at a slightly lower concentration to keep the fuel in their lines from freezing. They didn't do it for us. It was for their equipment. My uncle owned the esso in spruce home up until he retired a few years ago. He informed me about the equipment freezing and costing him 2000 bucks to get it fixed. He also said that acetone mixed into the fuel ,1 ounce for every 10 liters would improve fuel efficiency. I have been doing that in all our gas powered generators and air compressors and our fuel consumption has gone from 6000 a month to 5200 and change. Xylene and toluene also work to reduce fuel consumption.

 

[HyundaiGuy]

Originally Posted By: earlyre
why did you change plug types? if I've done my research correctly, that engine was designed for copper plugs(hence they installed them @ the factory). copper is a better conductor, produces a stronger spark, and burns hotter; which again, this engine was designed for. you sure you are getting full combustion? could that be where your lost mpg comes from?

also the coppers are a good deal cheaper, and are pretty darn easy to change.

my independent research has shown a definite difference in brands of gas. my old car, ('00 Sonata, 2.4l cyl.)seemed to run better on gas from flying J truck stops (Which other family members have referred to as Junk ) go figure.


The fuel usage increased before the plugs were changed.

I switched to the NGK Iriduim plugs because the research that I did indicated that they deliver a stronger, more uniform spark- in other words a more efficient ignition system.

I assumed that the copper Champions were put in at the factory as a cost saving measure due to the low cost of the car. That said, I can't tell the difference between the two. I may very well go back to the Champions at the next scheduled plug change.

 

[mechanicx]

The gas may come as a base from the same point but then the blend gets adds. There's when the differences and problems can ensue. So say in my town BP supplies all of the the raw gas and by requirement mixed gas to the non brands who buy from everyone. So for whatever reason they might send some to an off brand a sloppy mixture or some other brand might mix the additive, water and ethanol sloppy. I think the gas milage problem is from too much water added. One time the "same" supplier in town town shipped almost all additives and water and ruin many car's fuel systems. The final mixing is important. That's why I just get my gas at the Shell station where I think they care about the quality of the finished product. Sometimes station owners have been known to run a water hose to the tanks. Shell has shut down stations that engage in funny business.

 

[Cujet]

In addition to ethanol content, the actual octane may vary too. Your car likely has a knock sensor and lower octane fuel can result in the knock sensor pulling some timing, and therefore some efficiency.

It's generally said that "ideal" is enough octane to prevent knock and not a bit more. While modern engines operate under different conditions (such as variable valve timing) that affect octane requirements, they are still sensitive to knock.

Those of us who tune our engines with stand alone ECU's have dataloging and display information normal cars simply don't. It's quite interesting to see where the timing is on various brands of fuel. For many years, my local Chevron was, by far, the best.

 

[AuthorEditor]

I used to be one of those who poo-pooed (great word!) the idea that one brand of gasoline was better than another, and then I got an Exxon/Mobil gas card that gives me $0.15 off per gallon so I started almost exclusively filling up with that brand. Subsequently, I have noticed slightly better fuel mileage and much cleaner burning gas (less TB cleaning). I am pretty obsessive about what gas goes into my motorcycle and I check the mileage on every tank, and I have noticed a slight difference there too. The nicest change is less gunk build up in the throttle body. Why that is I don't know, but it seems to be the case. Before I tended to buy whatever was the cheapest gas no matter what oddball brand. I now think that is short sighted.

 

[Trav]

Quote:
if I've done my research correctly, that engine was designed for copper plugs(hence they installed them @ the factory). copper is a better conductor, produces a stronger spark, and burns hotter; which again, this engine was designed for

This would only be true if the actual firing end were copper, it isn't they are copper core with a nickel/chrome alloy for the electrode tip.
Platinum and iridium plugs also use a copper core, only the electrode tip is platinum or iridium.

Generally platinum and iridium tipped plugs use a fine wire design, this lowers the voltage requirement causing less stress on ignition components.
The precious metals are also much more resistant to gap erosion than nickel/chrome which provides a much longer service life.
IMO any manufacturer still using traditional plugs is doing so as a cost cutting measure.
Quote:
produces a stronger spark, and burns hotter

Stronger spark? No, in fact the fine wire precious metal plug will provide a stronger spark over a longer service interval.
Hotter? Plug temp is determined by its heat range. Too hot will cause pre ignition and too cold will cause fouling.

To test out the performance of precious metal plugs, put a platinum or iridium plug in a small engine and see how much easier it is to start and how smooth the idle is.
I put an iridium in my snowblower 5 yrs ago and now with almost 100hr on it it looks perfect and the 12HP starts first pull, ditto the lawnmower.
The reduced voltage requirement of these plugs is also perfect for magneto ignitions and will start with a much slower pull speed.

Finding an iridium NGK is easy, if the original is for example BR7ES the iridium will be BR7EIX. BR6HS would be BR6HIX
The most common flat head small engine plug is RJ19LM, J19LM, RCJ8, CJ8 can be replaced with B&S 5062 platinum from Tractor Supply or online the part# 796560

 

[HyundaiGuy]

[/quote]
Generally platinum and iridium tipped plugs use a fine wire design, this lowers the voltage requirement causing less stress on ignition components.
The precious metals are also much more resistant to gap erosion than nickel/chrome which provides a much longer service life.
IMO any manufacturer still using traditional plugs is doing so as a cost cutting measure.
[/quote]

That's exactly what i was thinking, that the iridium tipped plugs put less stress on other components and that copper was used by the factory because they are cheap. Thanks,Trav. I feel better.

Well, it looks as this car may just be fussy about fuel especially during winter. Looks like I may become a loyal BP customer, at least for gasoline.

 

[MNgopher]

I wouldn't base my fuel mileage comparisons on one tank of fuel - there is enough variability with just the gas pumps (even when properly calibrated) that I'd take it with a grain of salt.

That being said, if BP sourced their fuel from a different source, then there may be something to it.

In my neck of the woods, there was three distinct sources of fuels that we discernable at the pump. BP (Amoco), Holiday, and Superamerica all were sourced from identifiable sources and the makeup of the fuel in testing was different (all met minimum gasoline standards, but were formulated differently). More recently, two of the refineries involved have changed ownership, and sources aren't as clear. Personally, I've never noted a long term fuel mileage difference on any source, including Holiday. I did stop using Amoco at one time as it pinged in everything I owned.

 

[HyundaiGuy]

Originally Posted By: MNgopher
I wouldn't base my fuel mileage comparisons on one tank of fuel - there is enough variability with just the gas pumps (even when properly calibrated) that I'd take it with a grain of salt.


I've repeated this a few times, with the same results. And a previous poster may be right- this may all be with winter blend- even though it is 80 degrees outside.

I'm currently on a tank of Marathon, and I can tell the fuel mileage will be bad- 80 miles so far on this tank and the gauge reads between 3/4 and full. With BP, I'd still be on fill (but not over the full mark.) anything else would be just off of full.

 

[Trav]

You may want to consider running Redline Sl-1.
To start with use a full bottle and fill the tank then add a small amount every fill up, the markings are on the bottle.

With 35K there maybe some deposit build up on the intake valves and the injectors maybe a little dirty. The engine is still young enough to nip it in the bud so to speak.