Do I need a tune?

There are few modifications that you can apply on your car that will make as big a difference as a tune.  A few modifications will require that you retune for them; whereas others don’t require a tune, but you will not get the full benefit of the modification without one.  The question here is what does a tune really do?  What is being adjusted and what are the benefits to me?  What are the risks?

For all of you who are out there with stock engines, a tune can get you anywhere from a 25 HP to a 75 HP bump in power without modifying a single other component on your car.  How is this possible?  It’s possible because Hyundai warrants your car for 10 years / 100,000 miles for powertrain failures.  What this means is that in order to make such a guaranty on an engine that is mass produced on an assembly line will meet or exceed 10 years / 100,000 miles that the factory tune on the engine is not going to overstress the engine parts.  This means that the factory tune is very conservative.  Another consideration is that cars that require high octane (premium) fuel don’t sell well.  So the manufacturer needs to keep this marketing fact in mind when they design their cars, and they purposely retard the timing in order for consumers to be able to use 87 octane (regular) fuel.  Additionally, because the Genesis Coupe was offered with  2-liter turbo and a 3.8 liter normally aspirated trims with a price difference associated with the engine that the car was equipped with, the 2-liter turbo could not make as much power as the 3.8-liter engine.  Why?  Because paying extra for the 3.8 liter would not make much sense to the average consumer.  So, for you 2-liter turbo guys, the tune bump will also remove most of the difference that Hyundai built into the tune in order to sell more 3.8s.

So basically, what a tune on a stock engine will do is remove some of the safety factors that Hyundai built in.  Does this mean your engine is going to be less reliable and possibly not make it to the 100,000-mile mark before it dies?  The answer to that question is… maybe.  Modifying anything from OEM is a risk that the owner assumes.  Hyundai is not responsible for an engine failing when the owner changes the way that the engine was designed to work in order to meet the reliability promises that the company made to its consumers.  Consider this for a second…. you are a manufacturer of widgets.  Some of your consumers apply modifications to your widget because they don’t like the way that it works.  Some of those consumers end up breaking the widget with their modification.  Is it fair that they should hold you responsible for the widget breaking when they changed your design?

Let’s get back to what is being changed to allow your engine to output more power, but first, we have to get down to the basics and talk about how an engine makes power in the first place so that we can all be on the same level when we talk about what has changed.

How does an engine work?

A four stroke internal combustion engine works on the principle of converting gasoline into mechanical energy that rotates an output shaft.  Four stroke refers to the four cycles that occur for the engine to work.  Those four cycles are Intake, Compression, Combustion, and Exhaust.  An easier way to remember the four cycles is Suck, Squeeze, Bang, Blow…

During the intake stroke, the engine pulls in air using suction from the rising piston within the cylinder.  During this cycle, the exhaust valve is closed and the intake valve is open.  This air is mixed with fuel to provide an explosive mix that will be used later during the combustion cycle.

During the compression cycle, the piston moves up into the cylinder and compresses the air/fuel mixture into the smallest space possible before the mixture self-ignites.  Both the intake and the exhaust valves are closed to prevent the air/fuel mixture from escaping and both will stay closed all the way through the combustion cycle. Keep in mind that as the air/fuel mixture is being compressed a tremendous amount of heat is being generated as a result of the compression.  If the air/fuel mixture is compressed too much, it will self-ignite before the spark plug gets a chance to ignite the mixture resulting in an early combustion.  This is also known as engine knock.  The resultant early combustion (pre-ignition) of the air/fuel mixture rarely happens in a way that is orderly and the knocking sound you hear from your engine is the result of the combustion gasses trying to expand as the piston is trying to compress.  This puts a tremendous amount of strain on the piston, piston rings, valves, and piston rod in the affected cylinder.

Assuming that the compression of the air/fuel mixture went well, the next step is the combustion cycle.  The spark plug ignites the air/fuel mixture in a very precise way that results in an orderly explosion… that is, the air/fuel mixture does not ignite all at once, rather, it ignites from the spark plug radiating down to the piston head.  As the air/fuel mixture is burned, it heats up and expands pushing the cylinder down.  This is also known as the power stroke because this is the cycle that actually converts the fuel into mechanical energy that turns the crank and the output shaft.

The last cycle is the exhaust cycle.  When the air/fuel mixture is spent.. that is, there is nothing left to burn, the gasses must be expelled from the cylinder before the next intake cycle begins.  Any residual exhaust left in the cylinder will prevent the next intake cycle from pulling in the air needed for the next combustion cycle.  During this cycle, the exhaust valve opens and the piston once again pushes back down the cylinder to push the exhaust gasses out.

It should go without saying that this symphony of movement requires precise timing in order to make everything happen the way it should during every cycle. The piston movement must be coordinated with the valve movement, and the spark must occur a the precise time that it is needed in order to ignite the air/fuel mixture during the combustion cycle.

Tuning a car is not necessarily about turning up the boost

The spark plug ignites the mixture and the fire starts burning.  The speed of this flame front depends on the mixture, and how many air and fuel molecules are packed together in the combustion chamber.  The closer they are packed together in the same volume, the easier it is for the fire to jump from one set of molecules to the other.  The burning speed is also dependent on the air-fuel-ratio.  At about 12.5 to 13 air-fuel-ratio the mixture burns fastest on NA cars… for turbo cars that air-fuel mixture is from 11.1 to 12.3 (depending on boost conditions).  A leaner mixture than that burns slower.  A richer mixture also burns slower.  That’s why the maximum power mixture is at the fastest burn speed.  It takes some time for this flame front to consume all the fuel in the combustion chamber.  As it burns, the pressure and temperature in the cylinder increases.  This pressure peaks at some point after TDC (Top Dead Center). Many experiments have shown that the optimum position for this pressure peak is about 15 to 20 degrees after TDC.  The exact location of the optimum pressure peak is actually independent of engine load or RPM but dependent on engine geometry.

Typically all the mixture is burned before about 70 deg ATDC.  But because the mixture density and AFR in the engine change all the time, the fire has to be ignited just at the right time to get the peak pressure at the optimal point.  As the engine speed increases, you need to ignite the mixture in the combustion chamber earlier because there is less time between spark and optimum peak pressure angle.  If the mixture density is changed due to for example boost or higher compression ratio, the spark has to be ignited later to hit the same optimal point.

If the mixture is ignited too early, the piston is still moving up towards TDC as the pressure from the burning mixture builds. This has several effects:

  • The pressure buildup before TDC tries to turn the engine backward, costing power.
  • The point where the pressure in the cylinder peaks is much closer to TDC, with the result of less mechanical leverage on the crankshaft (less power) and also causes MUCH higher pressure peaks and temperatures, leading to knock.

Many people believe that earlier spark creates more power.  To combat knock they make the mixture richer.  All that happens really then is that the mixture burns slower and therefore hits the peak pressure closer to the right point.  This, of course, reaffirms the belief that the richer mixture creates more power.  In reality, the flame front speed was adjusted to get the right peak pressure point.  The same result (with more power, fewer emissions, and less fuel consumption) could be achieved by leaving the mixture at the leaner optimum and retarding the ignition more instead.

Turbocharging or increasing the compression ratio changes the mixture density (more air and fuel molecules are packed together).  This increases the peak pressure and temperature.  The pressure and temperature can get so high that the remaining unburned mixture ignites by itself at the hottest part of the combustion chamber.  This self-ignition happens explosively and is called ‘knock’.  All engines knock somewhat. If there is very little unburned mixture remaining when it self-ignites, the explosion of that small amount does not cause any problems because it can’t create a large, sharp pressure peak.  Igniting the mixture later (retarding) causes the peak pressure to be much lower and cures the knock.

The advances in power of modern engines, despite the lower quality of gasoline today, comes partially from improvements in the combustion chamber and spark plug location.  Modern engines are optimized so that the flame front has the least distance to travel and consumes the mixture as fast as possible.  An already burned mixture can no longer explode and therefore higher compression ratios are possible with lower octane fuel.  Some race or high-performance engines actually have 2 or three spark plugs to ignite the mixture from multiple points.  This is done so that the actual burn time is faster with multiple flame fronts.  Again, this is to consume the mixture faster without giving it a chance to self-ignite.

Higher octane fuel is more resistant to self-ignition.  It takes a higher temperature and pressure to cause it to burn by itself.  That’s why race fuels are used for engines with high compression or boost.  Lead additives have been used, and are still used to raise the self-ignition threshold of gasoline, but lead is toxic and therefore no longer used for pump gas.  Of course, a blown engine is toxic to your wallet.

Why the hell is my tune so damned rich?

What you probably have noticed from the numbers I provided above is that they are much higher than what your car is tuned to.  The reason for this is simple… nobody can guarantee that the fuel you put in your car is what the pump says it is.  A fuel pump is only as good as the calibration… and there are variances in calibration that allow for differences in octane levels and ethanol levels.  Additionally, you do not know how long the fuel has been sitting in the gas station’s tanks.  Condensation happens… and when it does, water is introduced into the fuel which can dilute it.

Because of these variances, tuners will not give you the absolute optimum AFR and timing required to maximize your performance… instead, they will leave a bit of a safety factor in the tune (on the rich side) to compensate for a little bad fuel.  It sucks that in the real world tuners have to protect themselves from liability by denying you maximum power, but that’s just the way it is.  Your car (especially your turbo car) is going to run stupid rich because nobody wants to be sued for negligence.

So… now that we got all the sciency crap out of the way…

What you should have gotten so far is that tuning is about balancing timing, fuel, spark, and air to produce an optimum burn which produces the maximum amount of power.  They are all interrelated and all have to be adjusted together to safely increase the output power of the engine.  Now that we’ve established what a tune does, the next question is, when do you need to get a tune?

If I mod (insert your mod here), will I have to get a tune?

Most bolt-on modifications (modifications that bolt on to the engine) do not require a tune; however, you may not get all the potential benefit of your bolt on modification without a tune.

Uh.. whut?

Okay… let’s take, for instance, intake and exhaust modifications.  The reason for modifying the intake or the exhaust is to provide a better path for air going into the engine and exhaust leaving the engine.  Because your car has a Continuous Variable Valve Timing (CVVT) which is controlled by a computer (your Electronic Control Unit or ECU), the computer can make on the fly adjustments to take advantage of the additional flow capacity… to a point.  The CVVT isn’t a magic box that can transform your grocery getter into a racing machine.  In fact, the CVVT is trying to optimize fuel economy rather than power.  Because of this fact, the ECU in combination with the CVVT will not optimize your power… only a tune can do that.

So, on to the list of things you can change without necessarily having to get a tune:

  • Intake Filter
  • Intake
  • Blow off/bypass valve (2.0T)
  • Intercooler (2.0T)
  • Charge Piping (2.0T)
  • Throttle body
  • Water/Methanol Injection
  • Nitrous Oxide Injection (3.8 up to a 50 shot)
  • Port and polished intake manifold
  • Port matched intake manifold
  • Exhaust headers (3.8)
  • Turbo manifold (2.0T)
  • Downpipe
  • Catalytic converter delete (Primary and Secondary)
  • Muffler delete
  • Exhaust system
  • Anything not attached to the engine
  • Anything that you plastidipped, hydrodipped, or painted

If you did not see your modification on the list, you must get a tune.  For you turbo guys out there, any modification to the stock turbo (CHRA replacement, wheel clipping, electronic boost controller, manual boost controller, turbo upgrade) will require a tune.


Note:  If you are custom tuned, you cannot make any major changes to your hardware setup without retuning.  A custom tune pulls every bit of power out of your car that the tuner can safely get out of your engine based on what hardware modifications you have on your car at the time it was tuned.  It is not safe to change that setup nor is it safe to allow another person to use your tune.  You should not custom tune your car unless you are forced to (changes other than bolt-on modifications such as custom turbo setups, pistons, camshafts, and etc) or unless you are reasonably sure that your hardware modifications are in their final state.


A dozen or so tune tips

  1. Never, not ever… lie to your tuner – Be honest about what modifications you have… it will have an impact on how you are tuned.  If your tuner requires certain bolt on modifications for a specific tune, get them and install them. Ultimately, it is you who will be buying a new engine if something goes wrong, so make certain that you do all you can to ensure a safe application of a tune.
  2. Although no tuner requires a Wideband O2 gauge and a Boost gauge, do not modify your tune unless you have some way of monitoring how that tune is working.  BK2 owners can get away with using an OBDII application using an OBDII scanner… BK1 owners:  You must get an aftermarket Wideband O2 gauge to monitor your AFRs since your OEM O2 sensor is a narrowband sensor and it is unable to monitor the precise AFR your car is at any given time.  If your tune messes up, you want to be able to have a visual warning before real damage is done.
  3. Always keep your OEM ECU tune unless you have modified hardware that requires a tune to operate safely – You may have to revert your car back to the stock tune for diagnostic purposes or if you cannot fill up with the fuel you were tuned for.  The only time you cannot ever do this is if you changed/added a turbo, changed your fuel injectors, or changed your camshafts.
  4. If something goes weird with your tune, try resetting the ECU first before crying for help – The ECU is a learning ECU and sometimes the writeable data tables can get corrupted.  Resetting the ECU will clear those tables and allow your ECU to correct itself.
  5. Do not purchase a piggyback tuning solution (like Dynojet’s CMD) if you don’t know what you are doing.  The piggyback is a very limited solution in that you can only control boost and fuel but not timing.  While you can add power by adding boost, it is an incomplete solution that can be dangerous if you enter the wrong parameters in the tables.
  6. If you know there’s something mechanically wrong with the car, do not apply the tune – The tune will not make things better, but it may make things exponentially worse.
  7. If you tune for a specific octane level, never fill your car with fuel that has a lower octane rating – This one will blow your car up.  If you are purchasing a tune, look for the availability of high octane fuel.  Some areas only have 91 octane available.  It would not make sense to get a tune for 93 Octane only to find out you can’t get it.    You can use higher octane fuel than your tune requires, but never lower.
  8. Be diligent about your maintenance schedule – A tune will place more stress on your engine.  Make sure you are following the OEM recommended maintenance schedule.
  9. A check engine light is not automatically a tune issue – Be smart about it.  If a check engine light comes on, get it scanned before calling for help.  Asking your tuner, “I have a CEL, what’s wrong?” is not a question that your tuner can answer.
  10. Do not use other people’s custom tunes in your car, they are custom for a reason.  Even if the modifications are the same, each car behaves slightly different and a custom tune that works great on one car can severely damage another.
  11. Be aware of the sounds.  Not all gas stations are honest and even though you just paid for 93 they may have just given you 87. If you hear pinging (firecrackers under the hood) immediately let off the throttle and examine what could be causing it.  Letting it ping and hoping it will go away will result in a damaged engine.
  12. Redlining and bouncing off the rev limiter may sound cool but your engine won’t like it if you do it for extended periods at a time.  Just because you can do something doesn’t mean that it’s necessarily good.
  13. Be prepared to assume the full cost of any repairs your engine requires if it breaks – Your car is warranted by Hyundai based on the stock tune for manufacturer defects.  Applying a tune that narrows the safety margin will result in a denial of any warranty claim you apply for.  Lying to your dealer by installing the stock ECU and then getting caught after the fact makes it more difficult for people with legitimate problems to get a warranty repair.  Additionally, the dealer could very well charge you a diagnostic fee for determining that you are lying.  If you like your warranty, you can keep your warranty.. but you cannot tune your ECU and expect that Hyundai will fix a problem that you created for yourself.
  14. Last but certainly not least, be smart.  Your tune may allow your engine to produce more power, it does not make your engine bulletproof.  If nothing else, a tune will cause your engine to wear down faster… especially if you are constantly beating on it.  If you are prone to driving around all day long with your foot firmly planted on the floor, you may be better off staying with your stock tune.  At least that way, if you do end up blowing up your engine, you are still covered by your warranty.

Why are there only a handful of tuners and who should I go with?

The reason why there are so few tuners who can tune a Hyundai ECU is because the ECU comes locked from the factory.  There are literally only just a handful of tuners who have broken the code, and of those, each to different degrees.  Even if the tuner can get into the ECU, there is literally no map available that tells the tuner what table controls what function, so the tuner has to make their own map.  If that weren’t a big enough pain in the butt, there is also a number of different ways that a tuner can get to the same basic outcome and each tuner has their own recipe.  While it may be true that there is often a better way to achieve a given outcome, it would be nearly impossible to quantify that ranking.  Instead, you will have to research and talk to folks who have different tunes with the understanding that opinions can be and are biased.

Open source tuning

There is currently no open source tuning solution for the Genesis Coupe.  There are a number of vendors who are rumored to be working on an open source, but up to this point, it has all been vaporware (all talk, no hardware).

Aftermarket ECU

A solution to having to rely on the handful of tuners who can tune the Hyundai ECU is to go with an aftermarket ECU.  2.0T manual transmission owners can go with a plug and play Haltech ECU; however, the 3.8 doesn’t have a plug and play solution.  If you have an automatic (2.0T or 3.8), you will have to go with a piggyback ECU solution as your transmission control unit (TCU) is mated to the OEM ECU and cannot work with an aftermarket ECU.  3.8 manuals can use a universal ECU to replace the factory ECU, but there is considerably more work to wire a universal ECU. Aftermarket ECUs have open source tuning software solutions available that will allow just about any tuner (including yourself) to tune your car.  This may not be a practical solution for someone who will only tune once and never again since the cost of an aftermarket ECU (without the tune) is more than double what the most expensive custom tune you can get costs.

Which tuner is the best?

With regard to our recommendation as to which tuner you should choose, you might be out of luck.  I suspect that this article will be around and read by folks years from now and any recommendation we could make today would most likely be invalid at some point in the future.  Do your homework and make the best decision you can make for yourself.

The bottom line

Just because you can, doesn’t always mean that you should.  Everybody reading this wants more power, I get that.  But to quote Peter Parker’s uncle (and Voltaire for you geeks out there)… “With great power comes great responsibility”.  If you modify the tuning spec of your OEM ECU, you own whatever happens afterward.  Some folks might tell you that if anything goes wrong, all you have to do is defraud the manufacturer by returning your car to stock before getting it looked at by the dealership.  This tactic may or may not work; however, you are asking the manufacturer to take ownership of something that you did to the car.  If you were big and bad enough to modify your car, be adult enough to take responsibility for what you break.  It’s only fair.

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About the author: Bob

I am a 21 year retired Army veteran with a background as a CH-47 helicopter Flight Engineer. For the past 5 years I have been a Genesis Coupe enthusiast and am currently a Moderator and Contributor for GenCoupe.com Forums, author of the "The Ultimate Genesis Coupe Newbie Guide to Modding", and the "Ask a Geek" sub-forum. Additionally, I am an administrator and event organizer for GenSport United as well as several other groups on Facebook. While I do not pretend to know all things with regard to the Genesis Coupe, I have dedicated a substantial effort to learn as much as I can and share it with whoever will listen.

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