Hyundai Sonata Fuel and Fuel System Questions

bill118bill118 Member Posts: 3
edited September 2014 in Hyundai
My car is 2006 sonata GLS I4, do you guys think it is a good idea to upgrade to premium gas?


  • backybacky Member Posts: 18,949
    Only if you like paying about 10 cents more per gallon for gas than you need to. The engine is designed to run on regular unleaded.
  • drdonrsdrdonrs Member Posts: 164
    why oh why would you even consider the proposition to switch to premium? The engine is controlled by a computer chip and is set for regular gas. Be happy that it is what it is. Even my Azzy also runs on regular. Of course you might want to make Exxon/Mobil and the other oil companies a little richer and your wallet a little thinner by an unnecessary switch.
  • bhmr59bhmr59 Member Posts: 1,601
    Gee, you're lucky if you can get by wasting only 10 cents per gallon. In my area of CT the difference in price for premium is 20 cents per gallon. ;)
  • jacknzonejacknzone Member Posts: 82
    Hi Bill118
    You may like to look at (Hyundai Sonata Real world MPG Numbers ) on page 61 #303
    I found it was around about the same , I'm back using 91 octane, 95 is a $1.529 a litre here . :D
  • patpat Member Posts: 10,421
    Seems to me that provides the definitive answer.
  • joe97joe97 Member Posts: 2,248
    Regular unleaded.
  • patpat Member Posts: 10,421
    Then, as noted earlier, it's only a waste of money to burn premium. The engine is not built to take advantage of it as everyone has noted.
  • effect18effect18 Member Posts: 41
    I have a 2007 Sonata Platinum ediiton. In the manual it says 87 or 89. I've been using 87 but have noticed minor engine knock. I took it to the dealer and they said this was normal, and will decrease over time since the car hasn't been broken in yet(I only have 700 miles on it).

    My wife recently(a few weeks ago) bought a 2007 Elantra SE. She mistakingly filled up with 89 one day. She told me of her error, and I told her next time use 87. When she filled up the next time with 87, she and I noticed the minor engine knock that my car had been experiencing. Not sure if this is how all Hyundia's are supposed to sound since these are our first Hyundia's. But I'm gonna fill up next time with 89 and see if my engine runs better.

    Any suggestions/experiences?
  • targettuningtargettuning Member Posts: 1,371
    You could try 89 octane but that is still a couple cents more than regular. With regard to the "knock" there should be none on either car using regular. There is, on both cars, a knock sensor that constantly fine tunes the timing and retards it if it detects any detonation (knock). It has been a very long time since new cars "knocked" so maybe what you hear (although it is hard to hear it inside) are the fuel injectors activating. They tick or click all the time and are audible at idle.
  • effect18effect18 Member Posts: 41
    I took a second look at my maunual and it says for the 2007 Sonata that gas of octain 87 or higher can be used. So i filled up with premium yesterday, and i'll let you guys know if I notice any difference.
  • targettuningtargettuning Member Posts: 1,371
    Sure, you can use any grade gas but Hyundai sets the minimum when they state 87 octain. The "or higher" part of that statement is purely optional (Hyundai is NOT saying you can't use it) so, yes, you can spend more for premium but I,like others here,say it is a waste of $$$.
  • bj02176bj02176 Member Posts: 115
    It may be a waste of money on the bigger engine, but not on th 2.7 awd, try 89 or higher and see if you do not feel more confident merging on rt 128 with it versus 87. No better gas mileage however.

    I thought they were saying in the manual to use 91 or higher for better performance, I could be wrong, but I think that is what it says in mine, and a true statement if that is indeed what it says.
  • targettuningtargettuning Member Posts: 1,371
    At one time we owned a 2002 Santa Fe with the 2.7 V-6 and AWD. Since I don't own it any longer I can't do the test you suggest but I never used anything other than 87 in it and don't recall any reason I should have upgraded to 89. I personally don't belive the minor increase in octane from 87 to 89 makes any appreciable difference in vehicle performance and ,for sure, none in fuel economy. It is, especially now, a waste of money for the vast majority of new cars owners. In fact, since probably 98% of all new cars are designed for regular (87 octane) and run perfectly well with it I can't understand why three grades are still available. Aside from some high end luxury cars, some luxury SUV's and very high performance cars premium (92 octane) is pretty much unneeded. You may gain optimal performance with those engines designed for premium if you use it but I'll bet not 1 in 100 Corvette owners could tell the difference if they used mid-grade instead and "lost" a few hp because the engine management computer "dialed back" a few design parameters because of it. Those engines are so massively powerful anyhow nobody would notice.
  • bj02176bj02176 Member Posts: 115
    I think they retuned the engine, however if you want to merge on rt 128 with just using 87 be my guest, around town the sluggish 87 is fine, but for highway merging 89 alternated with the next higher grade performs best. Just get the bigger engine and be done with.

    Or get a CRV 4 cyl which I believe will accelerate just as well as 2.7 hyundai on 87, and better gas mileage to boot.
  • bhmr59bhmr59 Member Posts: 1,601
    My '05 SONATA with the 2.7 V6 accelerates very nicely at 87 octane; it's designed to run on 87 octane. No need to spend the extra $.10 per gallon for 89 octane. I've never had a problem merging into traffic, even accelerating up to 80 just because some inconsiderate driver wouldn't back off for 2 seconds to let another car in.

    But then maybe your rt 128 is a different rt 128 than somewhere else, wherever rt 128 is.
  • targettuningtargettuning Member Posts: 1,371
    Thanks for your input but I fail to see the point of the post for the following reasons:
    1. I don't and never have merged on Rt 128 and I don't even know where it is.
    2. I have never stated I am or was unhappy with the performance of the 2.7 V-6 we had owned. Since we no longer own it it is a moot point.
    3. I am not in currently the market for a car "with a bigger engine" OR a Honda CR-V. I wasn't asking for your or anyone elses opinion about which car or engine I should buy.
    This started out to be my opinion about the uselessness of using a higher grade fuel than stated by the manufacturer and somehow now I have an argument about merging on Rt 128?
    If you feel better about your merge using premium by all means..go for it!!
  • hemi69chargerhemi69charger Member Posts: 2
    While filling up, I recently discovered that my 07 Sonata Limited doesn't have an "inner" door at the top of the gas tank filler neck. On all the other cars I've owned, I'd see a metal "door" that covers the filler neck once the gas cap is removed. I believe that door functions to prevent gas from the tank from splashing out. Can anyone who owns a 06 or 07 Sonata verify whether the inner door exists for me? Thanks in advance!
  • bj02176bj02176 Member Posts: 115
    I thought this was about premium gas, you did mention a Santa Fe 2.7, I said the same retuned engine in a 2007 with more horse power gets better acceleration with 89 or higher.

    Around town 87 may be okay, not on the highway. 128 is in Boston, it's the same for merging on any highway in a major city which Boston is.

    The manual for my 2007 says for better performance use 91 or higher, I find it to be true.

    Whether or not you own the car you are still saying other than 87 is a waste, on most cars it probably is, not on this particular Hyundai in my opinion.
  • wanna_azzywanna_azzy Member Posts: 41
    No "inner door" here, either. I'm not certain, but I think those were put in as an anti-theft/siphoning measure. Gas theft used to be a big problem. Probably too much work for thieves now, they steal directly from the gas pump by driving off without paying. Or use stolen credit cards. Anyway, no need to worry. Enjoy your ride.
  • bhmr59bhmr59 Member Posts: 1,601
    The topic here is "Hyundai SONATA premium gas."
  • hemi69chargerhemi69charger Member Posts: 2
    Thanks, wanna_azzy, for checking things out for me! I doubt the purpose of the "inner door" is for theft prevention, though. I think thieves can still siphone the gas given that the door is there, much the same way that the door can be pushed in (to open) when you insert a tube, e.g., the gas pump nozzle. I remembered reading somewhere--from my Intrepid manual (?)--that the door is referred to as a splash guard of some sort, but I could be wrong. Anyhow, it's good to know that I'm not missing anything. Thanks again!
  • targettuningtargettuning Member Posts: 1,371
    I think that inner door or flap a couple of inches or so down inside filler neck was originally a functional feature that prevented leaded fuel filler nozzles (which were larger) from being inserted in "unleaded only" vehicles. Since unleaded fuel nozzles are slim only they could be used. Now long after leaded fuel has disappeared this feature has also, it seems, disappeared. That said I haven't bothered to look on our 2006 Civic to see if still has one but if it does I don't know the current function. Couldn't be splash back prevention, at least while filling because the door is open at that
  • robert1955robert1955 Member Posts: 39
    That flap is only a splash guard to prevent gas from sloshing out while the car is in motion. An anti-siphon feature would be a mesh screen in the filler neck that lets gas in as you fill up but blocks a hose inserted down the opening.
  • targettuningtargettuning Member Posts: 1,371
    The splash guard idea would only be necessary if someone filled the tank to over-capacity (and only even then until you burned off a gallon or so) plus the screw on cap seals the tank and makes it a closed system for emission reasons. Over capacity is, not only filling the tank but also filling the filler tube to the top. Since this is a no-no with modern cars one shouldn't be doing it anyhow. So I am still at a loss to explain that flap...if it is still there on the newest cars and apparantly the 2007 Sonata (at least) doesn't have it. Maybe it is finally being phased out?
  • bj02176bj02176 Member Posts: 115
    Which could be my next vehicle if I swith to a sedan, if it doesn't run well on 87, then I will go with Honda or Toyota.

    I was responding to someone with a Sante Fe that posted on this forum with 2.7 engine.

    If you don't like my posts, don't read them.
  • patpat Member Posts: 10,421
    But the point that this is not a discussion about the Santa Fe is a valid one, so it would be best to just let that go here, no matter the engine. There should be a Santa Fe Real World MPG discussion where these things could be pursued.
  • jacknzonejacknzone Member Posts: 82
    my 04 sonata has a metal flap at the top of the neck ,of the tank .I thought it was to stop gas vapour or fumes escaping before and after filling your car up, why I say this , is because the Flap is on a spring .
    91 oct V 95 oct or 87 V 89 Oct
    I think for myself it's a waste of money to use higher octane than you need too !
    I posted this in March (Hyundai Sonata Real World MPG)page 16 #303
    I have put it to the test , Four weeks on 91 oct and four weeks on 95 oct ,got a average 22 mpg 91 oct and the same for the 95 oct , city driving / Trip computer average speed 32 kph / AC on. There was no noticeable different in performance .65 litres per tank 5 cents different in price between91/95 Using 91 for me over a year is a saving $85.00
    And I still using 91oct I think the best way to save money on the gas,is in the way we use our right foot.

    The Test is to try it out for yourself ,using the different Octane and the way you use your right foot. :D

    Cheers Jack
  • ms090870ms090870 Member Posts: 9
    I have a 2001 Sonata. The car have been incredible as far as dependability and economics. This car has 97000 miles on it and in the entire time that I have owned the car, the only work that I have had to do to this car is to replace a rear wheel hub. So needless to say I extremely happy with my car and will purchase an other car from Hyundai the next time I purchase a new car.

    I am currently having a problem with the filling up of the tank. The pump pops like the tank is full but it of course is not.

    I would appreciate any help you can give me.

    Thank you
  • canddmeyercanddmeyer Member Posts: 410
    Try another pump. This happens to me on a different make of vehicle once in awhile, but I attribute it to something going on at where I'm getting the gas as it's not consistent. I always noticed the pumps have higher pressure when there are less people fueling up and when the stations tanks are full.
  • patpat Member Posts: 10,421
    Some personally directed posts have been removed. Let's all play nice. It's too early for the heat to be getting to everyone and too late for cabin fever, is it not?

    Althought it's too hot for my tastes where I am today, no doubt!!
  • packer3packer3 Member Posts: 277
    There could be a problem with the vapor recovery system in the car
  • jdqjdq Member Posts: 3
    I was driving down the road one day and all of a sudden my engine cut out. The gas tank was full. After I towed it home I changed the fuel pump, which was unneccessary. I cannot figure it out. When I start the engine there is no smell of fuel in the engine compartment. I have the Hyundai Sonata 2002 4 cylinder. Can anyone help?
  • jdqjdq Member Posts: 3
    Thanks for nothing
  • lightfootfllightfootfl Member Posts: 442
    Possibly there are not many people here that have a 2002 mdl, and/or have had this type problem. You can't expect to have answers to every problem every time. I really think some people expect too much from these forums. If there isn't a reply, consider that your problem may be unique to you and your situation. Don't condemn the entire group.

  • njalannjalan Member Posts: 70
    I second. Ida should have contacted a mechanic, a repair shop or the dealership's service department first to identify and fix the problem and then share the experience here. The priorities got all turned upside down. If all such problems could be resolved in this forum, a whole lot of people would be out of a job and business closed for good.
  • huntet02huntet02 Member Posts: 7
    We just purchased an 06 sonota in March with 58K on it and I am only getting approx. 20 - 22 MPG. I live 35 miles out in the country and most of my daily work transit is on blacktop highway where the speed limit is 65 mile per hour so I should definetly be getting much better gas mileage since its mostly all highway. The first week I got the car we got somewhere around 24+ miles per gallon but NOW its averaging 20-22 MPG per the dash readout and is its right this is unacceptable.
    I came from driving a '95 Camry that with 246K still got excellent gas mileage; I do realize I'm now in a V6 but this is crazy I could be driving what I really like/want (truck) at this kind of gas mileage.
    I have reported this to Carmax were I bought it from and called my local Hyndai dealer to see what I an do and they are supposed to address this Monday.

    What is everyone else seeing gas mileage wise with these cars?
  • ray78ray78 Member Posts: 27
    Just traded 2006 LX V6 for a 2009 LMTD. Was getting Consistant 31 to 34 mpg on highway. 06 had 52K+ miles..
  • jlindhjlindh Member Posts: 282
    We have a 2008 V6 with about 9000 miles. I'm using 0w-30w synthetic oil and the tires are at 33-34 psi. I coast up to stop signs and, in short, do just about everything I can do to save fuel. Our driving is about 70/30 highway/city. Once in a while, we get 25.5 mpg for a tank, more often we're down around 25. The car is rated at 28 mpg on the highway, so depending on how you drive, 20-22 mpg on winter gas might be about right.

    The previous poster did not say what their average mileage would be for an entire tank of gas, but I'd be very suspicious of anyone with a V6 who claimed to average over 30 mpg for an entire tank unless they were doing a constant 50-55 mph.
  • huntet02huntet02 Member Posts: 7
    I think the past maintenance on my car is an important factor here and maybe it just didn't have all the maint. flushes and things it needed to run right, I think theres a lot of Maint things recommended by Hyundai that have never been done. Carmax where I bought it. put a new air cleaner in it and want me to drive though 3 tanks of gas and then report back to them. I won't let them off the hook. Then their mechanics who we never get to talk to say my bra on the front (thats made specifically by Hyundai) is lowering my gas mileage...BS!! Maybe 2mpg but were off at least 6MPG here....I'm still only getting today 21MPG unnaceptable!!
    My local Hyundai dealership says the bra should not make any difference and that they could run some DG fuel cleaner through it and a few other things that would definetly make it run like it should but it would cost $600+ and I'm out of warrantly at 60K but Carmax will make it right. So when their "new air cleaner" doesn't do much I'll be tellling them it needs to go to Hyundai.
  • jlindhjlindh Member Posts: 282
    I'm thinking that you might have misunderstood my posting. 25 mpg for an entire tank is doable on my car, but it takes a LOT of effort. If you're using gas with ethanol, don't have the tires overinflated, are in a location that still is selling the winter gas formulation, drive much in the city, don't use cruise control, don't baby the accelerator from a stop, don't try to avoid full stops whenever possible, don't coast up to stop signs and aren't using synthetic oil, 21 mpg might be a reasonable mileage.

    I went so far as to purchase an add on "ScanGauge" to show the instantaneous mileage the car is getting and indicate the best techniques to use. Based on my experience, I would guess that my efforts might be netting 3 mpg above my former driving style.
  • targettuningtargettuning Member Posts: 1,371
    "I could be driving what I really like/want (truck) at this kind of gas mileage"
    I don't think that any truck can AVERAGE over 20 mpg over an entire tank or tanks. That would mean a large portion of the tank (1/2) would be at the middle to high 20's range and I just don't see any truck doing that. I was just wondering if you are resetting the dash fuel economy readout after each fill-up? Otherwise the average can decrease as time goes on with differering driving situations cutting into the average currently showing. Reset for a fresh perspective at each fill-up. I don't think a 22 mpg average is to bad with a V-6 ...think of it this way if you get 19 city and 26 highway the average for that tank is 22.5 mpg.
  • ray78ray78 Member Posts: 27
    I drive 60 MPH and no jackrabbit starts and no skidding stops. Also most of my driving is on 4-lane highways. I also check my mileage at fillups.
  • jlindhjlindh Member Posts: 282
    Ray, are you saying that you got 31 - 34 mpg when you checked your mileage at fill ups?
  • ray78ray78 Member Posts: 27
    Yes- from Joplin, MO to Kansas City, MO and back I averaged 32.8 MPG.
  • jlindhjlindh Member Posts: 282
    I think that's outstanding for a V6 Sonata. I've fueled up at a station on the highway, reset the computer, pulled onto the highway, accelerated slowly to 65 and watched the mpg gradually increase to 29 or 30 mpg. I think 32 mpg is out of the question for my car, try as i might.
  • craigbrookscraigbrooks Member Posts: 420
    Did you do the manual calcs? You might be surprised.
  • sprkgtzsprkgtz Member Posts: 2
    My 08 Sonata is difficult to gas up. The gas nozzle "clicks off" every few seconds as if it is full even when the tank is practically empty. This has happened at numerous different gas stations, with different family members pumping gas. It is difficult to tell when to stop pumping gas because of this. Has anyone heard of an ongoing problem of this sort? When I spoke to the Hyundai service manager about this today, he seemed oddly eager to have me bring in the car for repair. This makes me wonder if it is anything potentially dangerous? He did mention that he has quite a few recalled Sonatas to work on right now. Recalled? What recall would that be? Did I miss something? :confuse:
  • backybacky Member Posts: 18,949
    Sounds like a kinked hose to me. Or maybe the carbon canister is full of gas. Have you ever "topped off" the tank? That can force gas into the carbon canister.

    The last recall by Hyundai on the 2008 Sonata was 18 months ago, for the OCS. I'd think those cars would have been fixed by now.
  • sonata77sonata77 Member Posts: 1
    edited February 2011
    I have the sAme problem with my 2002 sonata, it takes forever to fill up the tank. A mechanic friend if mine checked it and tried to fix it, it seemed that the carbon canister broke and the tiny pieces of carbon got stuck inside the ducts, This part in which the gas goes through looks like a saxophone, my friend took it apart and we saw all the carbon pieces coming out of it, but i guess we did not removed the one that was stuck, he said there is a way around this fix, to make the gas go straight to the tank, I wonder If a repair shop would do that and how much will it cost to fix. :cry:
  • backybacky Member Posts: 18,949
    It seems as if this "workaround" would disable part of the car's emissions control system. If so, I don't think a reputable shop would do that kind of thing. Might even be illegal to do that... not sure about that. I'd also be wary of any kind of "workaround" involving the fuel system from a safety standpoint.
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