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Alcon,

Good afternoon.

Question - 2017 Hyundai Elantra, manual - notice when starting engine first thing in the morning and taking off I get an engine anomaly and the car sputters; as if it were someone just learning how to drive stick-shift was driving.

After revving and driving for, roughly, 500 ft...it goes back to normal and I can accelerate properly.

Ideas?

Oxygen and fuel come to mind, but the given it only happens on cold starts and it's basically a brand-new car has me confused.

Regards,

Mark
 

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First thing I did with my new Limited, not the only vehicle was to gap the plugs at 0.025 inches, were all over the place very thin coat of anti-seize on the threads and packed the boots full of dielectric grease, if you don't, will never get them off.

Also can have a bit of moisture in your gas, settles to the bottom of the tank, ethanol loves moisture, don't use that crap.
 

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That's what I was thinking- Moisture &/or old gas. Might try a bottle of fuel dryer (isopropyl type ONLY, not the old cheap stuff).

Nicholas- I have not thought about checking the plug gaps.
My Elantra runs very nice & 36ish mpg mixed driving (60/40 highway/city inc some short trips). Why mess with success :)
 

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Coil on plug has a magnetic core, all ignition coils have one, its size and permeability determine the maximum amount of flux density it can hold just like a sponge can only hold so much water. Increasing the magnetizing force with more coil turns or current does not increase the flux, just helps to burn it up.

To store more energy need a larger core, space requirements or a core material of a greater permeability, more expensive, have bean counters to deal with.

The energy stored in the the core is measured in joules and is the product of voltage, current, and time, time is somewhat fixed, how long it takes that magnetic field to collapse, normally a fraction of a microsecond.

With a larger spark plug gap, it takes a much greater voltage to ionize the air fuel mixture, and since the energy is finite, the current goes down. Higher voltages with weak current are more subject to blow out by the turbulence in the combustion chamber. To put this as basically as possible, specifying greater gaps is tantamount to being without technical knowledge or insane.

There are consequences, with blowout, the fuel is not ignited in the combustion chamber reducing both performance and economy but is burnt in the catalytic converter causing it to fuse and restrict exhaust flow further decreasing economy and performance plus disastrous to your wallet.

Back in the mid 80's, our EPA told us to get rid of the variables like ignition timing by rotating the distributor, could never to this correctly, so goodbye distributor, out came the distributorless ignition system using crank and cam angle sensors. This required a coil per plug, but also had to deal with bean counters. so one coil had to fire two plugs, the one igniting, the other 360 crankshaft degrees apart. Very poor, don't blame engineers, either do it their way or will find somebody else.

Voltage had to be doubled, that halve the current, both had a weak spark and misfires, finally had to give up and use a coil per plug. Your Elantra has this.

Spark plug really has not changed much in the last hundred years, ceramics go back thousands of years, platinum and iridium is better doesn't get eaten away as quick as copper does by that spark. But still have that center electrode insulator and still burning carbon that builds up shunting that already weak spark back to ground.

Using top grade fuel and Seafoam to kind of clean up that carbon, still only good for about 15K miles, pull them and use my walnut shell spark plug cleaner to see that center insulator nice and white, do this one more time at 30K, at 45K replace them. One and a half drive around the earth is enough.

With summer gas holding at 65 mph, getting 50+ mpg, at 75 so I don't get rear ended, drops to 46, by manually shifting around town, crazy AT will shift into 5th gear at 25 mph, some idiots think this saves fuel, really puts a heavy load on the engine, get more like 35 mpg.

Don't even bring up this stupid winter gas, energy level is about 25% less, EPA insists on this, because it takes about a minute longer for the engine to warm up. They learned around in 1998 their engine emission control devices are worthless until the engine reached operating temperatures.

Put a heater in the O2 sensor, wanted this in the cat as well, these small engines don't have enough power to heat up a cat in a few short seconds. Was totally impractical, so went to the oil companies to add oxygen to the gas.

Still do not do emission testing on a cold engine, may learn oxygen enriched gas is also worthless, but this is the EPA. Yes, I could tell them this to their face. Ha, call themselves green, correct word, green out of your pocket.
 

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Sputtering on cold starts could be a number of things
Vacuum leak comes to mind
Weak plugs or even water in gas line
Etc ....

Would try dry gas or heet to clear water in tank (if there is any)
If that doesn't work then try looking for the vacuum leak
There are several methods. Youtube search would help.

Good luck
 

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Noticed a bit of hesitation yesterday morning when stepping on the gas. Hmmm, can;t be plugs, only 6K miles on them,

But did clear up, what my thinking is, cold and damp, the throttle by wire vane in the throttle body was sticking just a little due to some ice buildup.

A lot of guys are reading cold air is more dense and therefore get better performance by modifying that air intake system. What they don't realize, engine designers are not idiots, that cold air passes by the fuel injectors causing droplets that don't ignite very well causing misfires and poorer fuel economy and performance.

Better off to leave it stock, a certain air cleaner company comes to mind claiming this, ha, forgot their name.
 

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Discussion Starter #7
Ya, I use ethanol free 90 gas - I take care of my cars...last one was 17 years old before the return on investment of transmission repair didn't make it worthwhile to me.

Just a little perplexing a brand new car would be giving me troubles so early on.

I'll check gap on plugs and remit findings.

Thanks for information.
 

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Sounds like a flux capacitor issue to me.
Feel they confused a capacitor for an inductor, latter has flux, as does the ignition coil. But neither travels in time, need a flux capacitor for this.

This is what my Yura spark plugs looked like after only a couple of K miles on them, no way could I clean that black carbon off the center electrode insulator.. With my high voltage tester, were breaking down at around 2,600 volts, yes I had misfires.

Gave them back to my dealer, never got back to me, replaced them with Autolite XP5702's, still white with over 12K miles on them.

Disturbed by those long threads exposed inside of the combustion chamber, not doing a thing to secure them, but get carboned up and almost impossible to remove.

Thought this was a Ford thing, Hyundai should not have copied this.

Hyundai wants 18 bucks per plug, that is what I paid for a set of four XP5702's, not worth fighting for, must be getting soft in my old age.
 

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Well the thread would not be exposed in the combustion chamber so removal would not be a problem. The material used to make the threaded part is. NGK had to downgrade the coating that prevented thread binding because it was toxic if recycled. The cleaning is a problem with late model plugs because the porcelain is less dense to reduce cracking over long service life but once the plug becomes contaminated it's the end for it.
 
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