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Discussion Starter · #1 · (Edited)
Hello every one figured I would write up what i have done to get my car which is the 2019 elantra gt nline to with in a proper working order. This means proper idle and good handling. (Images can be found at this link) Hyundai gt Elantra

So when i first got my car it was declining quickly. by6000km my car would struggle to start had the crappiest idle and started to have the turbo put the car into limp mode. I also had poor handling and a bad vibration. The vibration is the only thing i have not had rectified yet but am close to solving.

Not everything is completely required but is defiantly a highly suggested update from me. So it has been a long road but at 26000km i finally have a engine that wants to idle correctly and stably and this is what i did to achieve this. First off i changed the oil weight to 5W40 which the dealerships should be telling you to do as there is a tsb out stating such. Second i changed to a set of hks40xl plugs and MSD Ignition coils I mostly went with these plugs cause they have a higher then stock heat rating which was an 8 for stock and 9 for the hks plugs. If you are tuned or modified tho I can recommend the hks45xl plugs as the 40's are for none tuned engines. The msd ignition coils the reason for a change tho these coils is because they are the best performing coils on the market. They produce a spark nearly 5 times stronger then the original coils meaning your 100% getting ignition in the every cylinder and it promotes stronger start up. it is a slight performance upgrade but in my mind a very required one.

what you need CRC valve cleaner, Throtle body/carburator cleaner, MSD ignition coils or other like products and a set of hks40xl plugs or hks45xl plugs if tuned.

So here is what i did to help correct this part of that issue. Alot of this you can do at home with basic tools and a extra person to help you out. ((!I recommend doing this at the end of an oil change as alot of this carbon will go to your oil as does the cleaner.!)) First off i removed the egr valve line from the top of the throtle body this will allow access to the intake system for a can of CRC Valve cleaner or like products to help break down those bad carbon deposits(this is not a 100% fix for most cars I caught the build up early so it helped but for higher mileage cars you will require a walnut blasting process as carbon the longer it sits the harder it gets to take off) You spray the cleaner down thru the the open valve into the throttle body in short bursts while the engine is at 1500 -2000 rpms. this allows the cleaner to Dissolve most of that build up on the valves and restores some power to the engine and hopefully corrects the idle. if it does not work you likely need walnut blasting to remove the buildup. Once that is done you let the engine sit for an hr or more then start it and drive it and let it smoke all the carbon out of the engine. After this process is done i Highly recommend pulling the throttle body and cleaning it with throttle body cleaner you can also use carburetor cleaner. be gentle with the throttle plate and do not use metal tools on it as any damage to it will require it to be replaced. Between the crc valve cleaner and the sludge build up it will quite dirty and likely stuck in an open position due to adaptation. this is also what causes a poor idle. once clean make sure the bolts are snuggle in place mine happened to be slightly out of spec all around which allowed air to pass thru the sides. I pulled my gasket and fully cleaned it and the mounting position.

(Explanation for carbon buildup and why you need to use a catach can)

"Next up we have engine protection. Now for those that do not know what a gdi engine is it basically means the designer put the injector assembly's in the cylinder rather then behind the valves. The gas in other cars with them behind the valves would allow gasoline to clean them and there for promote a healthy valve system for extended periods. But because the injector is not there the valves get dirty and they get dirty bad and quickly. The system is designed to take all the blow by and recycle it back thru the air intake or rather in thru those valves. Now you would think this should clean my valves but it unfortunately does not. Anything good and bad goes back thru this air way the PCV system and that's basically Oil, Water, Carbon deposits, and Gasoline. this creates a slurry of bad stuff that plasters your valves in a heavy carbon deposits which will in turn cause horrible idle. My car was so bad by 16k with out a can i had to do a decarbonization process and clean the throttle body cause the idle was just atrocious and getting way worse daily. You can mitigate this by installing a catch can which catch's most of this nasty stuff and in 7000km it is normally to have a mason jar FULL of this byproduct that causes huge issues. "

what you need 2 Catch cans, 1 check valve, 1 - 2 ft worth of high pressure of similar size as the pcv line hose and throttle body/ carburetor cleaner.

This allows you to come to the last place i worked on to get my car running correctly The Oil catch cans. This is a job that is very easy and VERY required of a GDI engine. It catch's the slurry of crap that is fired back into the system. You will want to remove the pcv valve completely from the car and check to see if it is free and clear you can unscrew it from the headcover. Shake it back and forth if you hear the little metal ball clearly it is clean but in most cases this will be stuck or making dull lazy thunking noises. You do not have to always replaces this part. try spraying a bit of throttle body cleaner in it and see if it helps clear it up. mine had a rock sized chunk of carbon blocking it and it cleaned out just fine with this method. Once this is cleaned and reinstalled you can now install the catch can. the can should have a Micron filter built into as this is what catches all the harmful gases and oils that come back thru the pcv pipe. It is setup so that the in side is facing the pcv and out is facing the air intake. Insure you install a Check valve on the intake side as this is a pressurized system and it makes sure that nothing can blow back into the can. get a good metal ball bearing valve as the silicon ones break down quickly. and will require replacement with in 5-8 months down the road. once hooked up be sure to check the can once ever 1 or 2 weeks in warmer climates you can likely leave it unchecked for 3-4 weeks as colder weather promotes alot of water in the system. Once this is done you can optionaly install the second can. it is not a required install it is jsut a precautionary one. the reason for installing this on on the rear port is because some times oil can blow back into this port and throw particles and oils into your turbo. this can cause damage and premature turbo failure. this can will very likely not collect any fluids over a period of a year but is good to have it.

There is 3 options for setting up this can. all options are fine and have no negative effects. First is basically to hook up the can band insure that both lines are hooked up accordingly you can also install a air filter on this can to help release crank case pressure. Second option is to simple close the inlet side of the engine from the pipe on the air box and installing a filter on the catch can pipe instead. I personally did this on mine as it runs zero risk of blow back into my system. The thrid option requires some extra work or a third out pipe from the catch can. Basically it routes the secondary pressure and air to the rear intake just after the box. this mod requires 2 check valves. it is more preferred to tuned engines. the head side is simply filtered.

Additionally you can add a performance air filter to the air box as well or go full after market but it is not required to make the engine run more stably. I do recommend the K&N air box dry filter tho as it will last you for many many many more miles then the stock filter and allows the engine to breath better.

This concludes what i did for engine performance next up is suspension and handling of the vehicle.

So what you will need here is:12 set of lower engine mount bushings Power flex or like products I personally like the yellow power flex bushings as they are closest to stock and make zero vibration and a set of ridged collars for the subframe both back and front is required for the best performance.

(((Explanation of what it does and why it makes it better)) So here i will explain what it does and how it affects the ride quality. So lets start with the bushings. these are by far the most important upgrade to the car in my belief. The original engine mount allows for WAY to much flex of the engine which results in the engine moving back wards and forward by nearly 1-3 inchs each direction under load. This in turn creates what we call Wheel hop. its basically the bounce of the tires on the ground which can cause damage to your suspension, engine mounts, and even the engine and exhaust itself after long period of time. With this much movement parts on the engine will move and rub and eventually break as things like fuel lines are solid even the flex pipe in the exhaust can give out after a bunch of abuse of this kind. mind you most of it will be a long time down the line but i have heard of engine fire issues due to to much flex breaking fuel lines. so unless you drive like your driving miss daisy you will cause significant damage to your vehicle over a period of time. The more durable silcon bushings like power flex produces allows to very little of this to happen and keeps your engine firmly in place and not at the cost of judder back into the unibody of your car. The bushings are also only 54$ so at that cost you can have a much smoother ride and beable to do it yourself ! 4 bolts and your done its as simple as that.

This brings me to the second much required upgrade which literally only runs you maybe 74-100$ cad. Ridged collars are basically a washer with a insert on it made from billeted aluminum that fit in and close the gap around your subframe bolts. The sub frame has nearly a half inch gap in totle to freely move and yes it does move when you take a corner mine were so tight i broke a 3/4 ratchet on them and it still moved under cornering. what this translates to is body roll or a feeling of sliding when the car is not actually sliding. When you take a turn at any speed this will allow the subframe to shift from one side to the other depending on the direction you are moving and will show no signs that it has done so when looking for an explanation why. the ridged collar fills the void and also helps in snugging the frame firmly to the car this does alot of things for the vehicle as well. First immediate thing you will notice is how your car handles bumpy roads. Before the car would feel rough or clunky while now it feels more smooth more firm and as if the suspension is finally doing its job at absorbing road shock. The second it does is when taking a corner you no longer will feel as if you are sliding around the corner on ice it makes the car feel firmly planted and rigid allowing the suspension to do its work which will also aid in keeping your tires from getting cupped at proper inflation pressures. )


Ok so now we come to the handling portion of things you may require a hoist or set of 4 jack stands to perform this last part all the work is under the vehicle. Install is preaty simple and straight forward. First off remove the lower engine mount. you will want to loosen the bushing bolt while its on the vehicle then remove. take the bushings out and if your like me clean the mount and paint it to help keep it corrosion free. Install your performance bushings then put it back on the car DO NOT only replace the back one replace both bushings there is a reason there is 2 pieces in the box don't put lipstick on a pig and expect it to work out do the job properly. Once reinstalled this will reduce the wheel hop by nearly 80% and help with the handling of the vehicle. Now moves us to the ridged collars. while the car is properly supported remove each subframe 1 at a time placing the ridged collars in and snugging before removing the next one. I would recommend loosening all the subframe bolts ahead of time before pulling bolts as this will insure your subframe is 100%in alignment and centered. do this for both the front and the back it should not take more then 30minutes to complete both tasks and the results will speak for themselves afterword's.

And this concludes my guide I will be linking images to help aid in the process. I know this post is a little long winded but a good explanation is better then a poorly writen mysterious one. cheers

Jake AKA Deathjam4
 

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Discussion Starter · #2 ·
Additionally I am adding another issue i had that i let the dealer handle. This involves the turbo on the 1.6L engine. There is no parts required unless they are damaged and continue to leak fluids. So one of my issues was erratic idle and complete turbo shutdown at completely random intervals and for often no reason. This helped with my car and has thankfully corrected all the underlying issues.

The only thing that had to be done and was literally a less then 15 minute fix was to simply have the turbo's oil lines torqued down to spec properly. since this has been done my car no longer has a stutering boost and has not had a complete shutdown. A sure sign of loose oil lines is oil on the back of your drip tray. Mine was coated in oil and i found this was the problem. if thisgoes on to long it can ruin the oil seals and create a loss of oil or oil consumption issue.
 

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Got my MSD coils in. Initial results are promising!
  • smoother idle
  • I haven't had sulfur smell yet
  • stumbles and misfires basically gone

I reset the ECU. The car usually runs pretty well after that for a day or so. I'll know by Monday whether or not it's just a fluke.
I still have high total fuel trims when idling +10-15. This keeps leading me to think there's a vacuum/boost leak somewhere, but I have no other cars to compare to, but it's running the best it ever has at the moment 👍👍👍
 

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Discussion Starter · #6 ·
I would like to add an update to my post. So to date my vibration was my my windshield slowly peeling off the glue on the car. i had 6inchs left of it glued to the car by the time i caught it and had the dealership reglue it to my car. my vibration for the most part has gone.

That aside i have been maintaining certain things to make sure my car maintains its relative smooth running status. I have had a few hiccups over the time i first posted but now have gotten the car to the point where it no longer blows garbage thru my pcv system and my spark plugs after 20k are almost perfect in shape.

doing a few things regularly certainly helps maintain a healthy running motor in these cars. So a few added notes. At 17k i crc the valves they were fairly dirty but not horrible this cleaned them enough that the car ran smoother afterword's. after this i have used injector cleaner thru the tank every other tank of gas. I find if the car starts to produce an unsteady idle or hickups a bottle of crc tank additive works extremely well at cleaning your carbon out. Also maintaining the pcv valve every 10k is a must as it can and does get stuck if the car is catching oil fuel and water in the can. just simply remove it and run carb cleaner or brake cleaner thru it shake it to make sure it actuates right and blow it out with a air line or your lungs. i had to do this early cause both my catch can valve and the pcv valve were getting varnished. I have also cleaned the throttle body once every 15k. the first time i cleaned it it was so bad the flap had stuck open nearly 20% because crud was blocking its rotation. this causes bad idle. and can and does get very dirty with out a catch can. I will also monitor my oil some times it will be good for a little longer other times it will not so i change it when the consistency has degraded.

I would also like to add that if none of this helps fix a poorly running engine then you likely need the carbon cleaned from the engine as it has gotten to the point where none of these other steps are useful. its best to have the preventative measures in place before it gets to bad. I literally had a great deal of issues before i hit 10k. crc cleaning the car does help in the sense that it will help the valves seal better but only if its a light layer of carbon. there is other methods of cleaning the valves other then walnut blasting as well. its just more time consuming and for those that are more mechanically inclined.

But for those that would like to do this here is a helpful video for those people. Carbon Cleaning with legitstreetcar
 

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This is excellent information. Greatly looking forward to seeing the images.
An update for mine:
Getting the MSD coils is definitely an improvement, but after a week or so, it's basically back to garbage with slightly more low end power than before.
What happens to me is it runs great after wiping the ECU and after driving it, it slowly returns to ultra high fuel trims and runs like trash. Admittedly, it took longer than usual to get back to complete trash. It usually happens within 100 miles or so, but took much longer with the new coils.

TLDR: helped a little -- still runs like garbage
1942
 

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Discussion Starter · #8 ·
I decided to make a video of me doing the basic valve cleaning and I added some basic info and the process of it being done. if you have a bad idle it may help you out as it sounds to me like you likely have carbon stuck on the seats. My car was starting to backfire as well i did all my cleaning steps and she runs nice and clean. hope it helps and cheers
 

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Discussion Starter · #9 ·
An update for mine:
Getting the MSD coils is definitely an improvement, but after a week or so, it's basically back to garbage with slightly more low end power than before.
What happens to me is it runs great after wiping the ECU and after driving it, it slowly returns to ultra high fuel trims and runs like trash. Admittedly, it took longer than usual to get back to complete trash. It usually happens within 100 miles or so, but took much longer with the new coils.

TLDR: helped a little -- still runs like garbage
Yes i been having the same issue and been fighting it for some time now. I am preaty sure its caused by the injectors. they are dumping to much fuel int othe cyclinders causing issues like backfire and poor idle. Eventualy ill have to just break down and strip the intake manifold off and clean the carbon off. I am still attempting to get the dealership to replace the injectors but they were trying to tell me my catch cans were causing the problem which i took them off and it still runs like crap lol. I hope to have a full resolution soon as i have a bit more time to take it back in again. I am still waiting on having them repalce my lower control arm bushings. they ordered them but i just have not had time to go in with the car. ill keep people posted.
 

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Yesterday, I installed the N75 boost controller replacement. Although I haven't had much time to test it, the issue is basically gone. I have to regap my plugs and let the computer relearn, but I'm pretty sure this has been the problem since day 1.

Instead of stuttering and falling flat on its face, it just moves. Takes off. Shifts feel better and it pulls at any rev. It even sounds different! I can't speak for everyone with this issue. I'll keep y'all posted.

 

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Stock plugs and coils. 87 top tier. Oil change every 5-6000km with CRC turbo intake cleaner before dropping the oil and fuel cleaner in the tank. 2 cheap catch cans with no restrictions or check valves. Zero issues with idle or misfires @ 43000km. I may do the solenoids but I'm not buying the cheap EGR VCV's N75 calls a "race valve" for 300 or more percent markup.

Also the normal seafoam does nothing for intake deposits.
 

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Part number for the n75 race valve is 7.00470.07.0. Got mine on ebay or Amazon for MUCH cheaper. Cut the bracket off and reused the stock rubber mount. Squeezed the stock hoses in (took a while). Also had to make my own connector. I can look up the parts for that if interested. Much better than stock, also seems better than the one sxth sells also.
 

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Cross-posted from Uneven acceleration, for those of you who don't want to waste a bunch of precious time and money:

"...I swear by Gumout products. I used them regularly with my Fiesta ST (FiST, to enthusiasts of the car, sadly discontinued in the Americas), about once every month and a half, or so.

"I don't really know why it took me so long to use a bottle with my 2020 Elantra GT N-Line; but, I stuck in one of their Complete Fuel System treatments for GDI vehicles ($4.77 USD at Walmart) about 3 weeks ago, on an empty tank before fill-up and... Whoosh!

"In Sport mode -- even in the plain-Jane, usually hiccup-y DCT -- the danged thing took off like its butt was on fire! And it's still running hell bent for leather,1.5K miles later.

"Looking like my idea of a sport car after all, wasting all those big-bore lead sleds when challenged... This is getting good!"

Product page:

Walmart sells it online for $4.44 USD:
NOTE: The treatment packaging I use has GDI prominently displayed on the label; but the detail on Walmart's page says:

"CLEANS
GDI/direct and port/indirect fuel injectors, intake valves and ports, piston tops, cylinder heads, combustion chamber

CONDITIONS
Fuel to fight ethanol and water corrosion

PREVENTS
Future carbon buildup.

BEST FOR
Maximized performance and fuel economy in one fill-up, reduced emissions

DIRECTIONS
Oxygen sensor safe. Safe for use in turbocharged and supercharged vehicles. Will not void OEM/manufacturer’s warranty. Add entire bottle to nearly empty gasoline tank, then fill tank with up to 21 gallons of gasoline. For best results, do not refill tank until near empty. Use every 3,000 miles." (Emphases mine)

Might save y'all some time, headaches, heartache and busted knuckles...

Food for thought.
-zed
 

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Understand this is a somewhat older thread, but I wanted to add two simple things to this:

1) Our 2018 EGT Sport had incorrect and unevenly gapped spark plugs from the factory. I re-gapped them to factory-spec.
2) MAC BOV solenoid upgrade was done

After only these two things, though fuel economy has remained largely the same, power delivery is better and a lot more even. Flatspots are gone. Flies like it should have from Day One. It is much snappier and responsive. Builds steady power with full-throttle freeway merges.

Since our work situation changed, we have two cars but now one of us works from home full time, and the other is hybrid. We don't drive a lot to begin with and we use the EV for errands, so, our EGT only has 15K miles at this point.
 
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