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Discussion Starter #1
Not sure what this is but just noticed this a couple days ago and seems to be getting worse.

While driving I'm feeling a lurch or misfire type feeling but I don't have any warning lights. At first I through I just had the gear to high so I switched to a lower gear but it kept happening.
Also I noticed today while idle at a light the rpms would drop ever so slightly and I'd feel this feeling for a couple seconds then it would go back up to the normal idle rpm level.

Could this be a bad gas issue? I use only 93. Should I put some fuel injector cleaner in or just take to Hyundai to get this checked out? It happens when cruising and at idle.

I only have 1,000 miles on the car and just started to notice this.

Thanks for the help!
 

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Is it only when the engine is cold? Is the ac on? Do you use top tier gas? Do you drive the car hard occasionally?
 

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Discussion Starter #3
Is it only when the engine is cold? Is the ac on? Do you use top tier gas? Do you drive the car hard occasionally?
AC/HEAT is on but never had this feeling with any other car when AC/HEAT was on.

Gas probably isn't top tier but is 93.

Seems to do this when engine is warmed up as well. It never did this before until 2 days ago.

I haven't ever red lined it. I'm not sure what hard would be considered to be but I probably haven't driven it very hard since I've had it.
 

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Probably just a bad tank of gas like you first suspected. Occasionally I'll notice a slightly rough idle if I've been driving easy for a couple days but all it takes is a few full throttle runs through a couple gears and it clears up. Fuel system cleaner may help as well, especially if the gas you've been using doesn't have a high level of detergent.
 

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Either utilize some Dry Gas or Techron Complete Fuel system cleaner. Winter blend gas is crap. Drive the car as you normally would and relax, your covered.
 

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Discussion Starter #6
I scheduled to bring it in next Tuesday because that’s the soonest they can get me in at my dealer. The car did it bad at a light just sitting and the car shut off. The service guy said it was too new to put in cleaner so idk I guess if it doesn’t clear up I’ll be taking it next Tuesday. He said to run the gas out and see if it keeps doing it. He said usually when it’s gas a check engine light would come on or go on and off which mine is not doing.

I also hooked up my obd reader and no errors came
Back.
 

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It's not to new and the alcohol in the FI cleaner or Dry Gas will dry up any possible water in the fuel system. The service rep is useless, he doesn't know what he's talking about. :rolleyes: If the gas is run out, the water and condensation will remain in the fuel system. This is why you run drygas or techron thru the system. Both will allow the water to mix with the fuel to burnoff in the cylinders.:smile:

It's not going to throw a malfunction code unless it gives you CEL or annotates a malfunctioning system. Water in the gas won't cause this, unless it causes the car to go into limp mode.

You need to realize your service rep doesn't know the first thing about the VN. Few do and don't have the expertise to diagnosis or suggest a sufficient remedy.
 

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Discussion Starter #8
It's not to new and the alcohol in the FI cleaner or Dry Gas will dry up any possible water in the fuel system. The service rep is useless, he doesn't know what he's talking about. :rolleyes: If the gas is run out, the water and condensation will remain in the fuel system. This is why you run drygas or techron thru the system. Both will allow the water to mix with the fuel to burnoff in the cylinders.:smile:

It's not going to throw a malfunction code unless it gives you CEL or annotates a malfunctioning system. Water in the gas won't cause this, unless it causes the car to go into limp mode.

You need to realize your service rep doesn't know the first thing about the VN. Few do and don't have the expertise to diagnosis or suggest a sufficient remedy.
You may be right about the service tech. I think I will go ahead and try the techron. It's still doing it today even after driving it a bit hard so hopefully techron will fix the issue. If not then guess I gotta go take it in on my day off.

Thanks
 

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I wouldn't do anything to fix it, it's a warranty issue (assuming you haven't modded it or anything). But you can get an OBD2 port reader and the app Torque Pro- all for around$30, and check some things.

AFR and fuel trims at idle and 3500 RPM, max spark advance your getting and fuel pressure. If it's happening only once the car is warmed up, it says a lot. It's not fuel then. It's probably not a misfire either because you would have gotten a misfire CEL by now.

When the car is cold, it's running open loop. So if you have a vacuum leak or something, it'll run ok. Once the car warms up and runs closed loop, it'll read the O2 sensors, adjust for problem and that's when it runs like crap. But it can be a lot more than a vacuum leak. Your OBD2 reader + Torque Pro gives you a starting place to look for problems.

Whatever the issue is, it's not throwing a CEL yet so the dealership (most don't do diagnosis) might give you the big blow off. Bear in mind, that warranty DOES NOT REQUIRE that you go to the dealership for warranty repair! You can take it anywhere that has ASE certified techs.
 

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I wouldn't do anything to fix it, it's a warranty issue (assuming you haven't modded it or anything). But you can get an OBD2 port reader and the app Torque Pro- all for around$30, and check some things.

AFR and fuel trims at idle and 3500 RPM, max spark advance your getting and fuel pressure. If it's happening only once the car is warmed up, it says a lot. It's not fuel then. It's probably not a misfire either because you would have gotten a misfire CEL by now.

When the car is cold, it's running open loop. So if you have a vacuum leak or something, it'll run ok. Once the car warms up and runs closed loop, it'll read the O2 sensors, adjust for problem and that's when it runs like crap. But it can be a lot more than a vacuum leak. Your OBD2 reader + Torque Pro gives you a starting place to look for problems.

Whatever the issue is, it's not throwing a CEL yet so the dealership (most don't do diagnosis) might give you the big blow off. Bear in mind, that warranty DOES NOT REQUIRE that you go to the dealership for warranty repair! You can take it anywhere that has ASE certified techs.
This is bad information. Hyundai requires it to be taken to a Certified Hyundai Service Department for warranty repairs.

For service, you can take it elsewhere but for warranty/warranted claims and repairs, it has to go to a Hyundai Service Department. Hyundai will not recognize any other workshops to do warranty repairs. An unauthorized shop, is unable to get the warranted parts from Hyundai to do such a warranted repairs, without the owner carrying the full cost of replacement and man hours required to make the repairs.

Again this is bad information. All Hyundai Service Centers do general diagnostics, with a Hyundai GDS. You take it to a Hyundai Dealership Service Department with a CEL or not, the first thing they'll do is connect the GDS to diagnosis any trouble codes.

Hyundai is aware of the fuel issues on some of the VN's and will first replace the FI's. A vacuum leak, will be identified in the ECU as a vacuum pressure change and throw a trouble code which will be a P0175 or P2282 in the ECU, it's not a vacuum leak. It will throw a P0171, if it's fuel system related

Causes of the P0171 code may include:

A faulty fuel pressure regulator
A weak fuel pump
A clogged fuel filter
A faulty powertrain control module
A vacuum leak
Faulty injector(s)
Faulty oxygen sensor(s)
A faulty mass air flow sensor
Loss of power
Check Engine Light
Hesitation or stumble from the engine
Engine may be difficult to start
Engine may die
Catalytic converter damage may result if this code is stored for a long period of time

PO172

A dirty mass air flow sensor overstating the amount of air entering the engine which may cause excessive fuel delivery
A bad oxygen sensor
A leaking fuel injector allowing too much fuel to enter the combustion chamber
A faulty fuel regulator, which may not be regulating the pressure of the going to the engine as it should
A vacuum leak
A possible fault in the coolant system such as a stuck thermostat or bad coolant temperature sensor
Worn spark plugs
Malfunction Indicator Lamp (MIL) illumination with P2279 diagnostic trouble code set

Vacuum leaks
Clogged or faulty Mass Air Flow sensor (MAF)
Faulty PCV valve or other parts of PCV system
Stuck open purge valve/solenoid
Faulty oxygen sensor
Improperly installed aftermarket intake
Low fuel pressure
Clogged-up catalytic converter

There are many others the ECU can throw depending upon the system involved; Body Control Module Fault Codes, Hyundai Trouble Codes etc., It might even be a MAP sensor malfunctioning. This is why it's necessary to start simple. If it's not; air, you move onto fuel, if it's not fuel it's spark. It can be combination of the two or three also. Add some Techron to clean the FI's. If this doesn't work add Dry Gas to remove any water in the system. If this doesn't work, take it to your Hyundai Dealership Service Department and let them deal with the issue. It's their problem and they need to fix and document it for the Hyundai Engineers.
 

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Discussion Starter #13
Well car just shut off while driving, luckily was by a gas station and coasted in. Obd reader is giving 4 misfire codes on all four cylinders. Going to get hyundai to come get it towed.
 

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Discussion Starter #15
P300 P301 and I think it just kept going up form there for each sensor. There were 4 misfire codes and 1 random
Misfire code which might have been the p300.
 

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P301 misfire on cylinder and the P300 code that is generally related to more than one cylinder. Could be one of the following but generally not Internal Engine Problems with and engine this new.

Low Fuel Pressure
Vacuum Leak/won't shut down the engine but go into limp mode.
EGR system malfunction
Internal Engine Problems (such as low compression)

or

Faulty Coil Pack
Faulty Spark Plugs and/or Wires
Camshaft or Crankshaft sensors / This is what I believe is causing the issue, especially the way you described it.
Ignition module
Computer

The first two test your service center need to be doing are a fuel pressure test and cylinder leak down. Then progress from there.

Did they do the NHTSA Knock Sensor System software upgrade recall yet?
 

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Sorry you're having trouble with your car dude. I hope they have you back on the road quick. Misfires can be almost anything, let us know what it turns out to be
 

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I wonder if this might be related to the guys experiencing hard starts and leaking fuel injectors.

My car hasn't shut off yet but it still occasionally takes a few seconds to start up and I also intermittently get a slight feeling of a misfire (it's definitely not bad enough to be a full blown misfire yet). Without anything to really go on I gave up until the car throws a code but I know something is off...
 

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Discussion Starter #19 (Edited)
Got a call back from service at Hyundai and they said it's the gas. Has too much water in it. They said it's probably because around here a lot of people don't get 93 and the gas sits too long.

It's not covered under warranty so they are going to clean the lines out and take the gas out of it.

Going to cost me $250. Hopefully they don't charge me for the loaner car as well.

Never had this happen to any other high performance car I've owned so hopefully they know what they are talking about and this fixes the issue.


Needless to say it's pretty frustrating. Hopefully no other damage could have been caused by this.
 

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The service tech might not know about the VN but he's probably right, it's not likely to do anything. Unless you're filling the car up with gas that's specifically sold as ethanol free you don't need fuel drier. 95% of the gas sold in north america is 10% ethanol blend and that will take care of way more water than a bottle of drygas will.

https://cropwatch.unl.edu/ethanol-and-water-contamination-—-comparing-water-removal-additives
You're simply mistaken and obviously not actually used any before.

The test you quoted, is for small engines and engines used intermittently. This is why you utilize a fuel stabilizer for such engines and storage. We however are talking about a VN that carries over 13 gallons of fuel and is not being stored for long periods of time.

The issue is the amount of water the fuel contain and the amount of condensation that's not being burnt off during combustion. Left to its own, E-10 and higher Ethanol fuels will separate over long storage and leave a brown sludge in the tank if an Ethanol Fuel Stabilizer is not utilized.
Water can cause an engine not to start. In tests by Gregory Davis at Kettering University small engines failed to start when water was introduced at levels greater than 20 teaspoons per gallon. In the study high levels of water contamination were equally bad for pure gasoline and ethanol blends.
A large amount of water contamination in a fuel tank is likely equally bad for E-0 or an ethanol blend. Avoid water contamination by covering small engines or storing them in a shed or garage.
For reference; 20 teaspoons of water in a 14 oz cup is 1/3 of the size of the cup utilized. In 12 gallons this amounts to over 5 14 oz cups of water, which is dispersed into the fuel system thru FI, pumps, filters, fuel lines and tank.
Got a call back from service at Hyundai and they said it's the gas. Has too much water in it. They said it's probably because around here a lot of people don't get 93 and the gas sits too long.
The water comes from separation in the storage tanks and the active filtration of the station not removing or filtering it. Don't go back to the station you got it from and report it to the state to make the seller fix the filtration system.

However, you always start with the obvious first and work you way into one of three system, Air, Fuel, and Electrical. It's simply dynamics of the engine. You eliminate one before you go to another. The most expedient route is, to utilize a fuel dryer to quickly eliminate an presence of any excess water in the fuel system and then fill the tank with a premium high test fuel to see if it eliminates the issue. If it does, then the problem is solved. If it doesn't moving forward then you check, fuel pressure and so on. This is common mechanical knowledge and experience.
 
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