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Rough Idle

155K views 231 replies 73 participants last post by  robertkoa 
#1 ·
My 2011 Elantra has a slightly rough idle at stop lights. It doesn't happen ever time, and some people probably wouldn't even notice it, but at every few/several stops it idles a bit rough. When I recently had it in to Hyundai service for the ECM update, I asked them to take a look at it. Of couse, they couldn't replicate it at the time, so they couldn't do anything to address it directly. The service manager asked if it happens when the A/C is on or off. While I didn't know the answer at the time, it seems to happen with it both on or off. He did say that the ECM update may address/fix the issue, but unfortunately it didn't. While it's not a big problem, it's a minor annoyance I'd like to get fixed (as I need to enjoy my ride at all times ^_^ ).

Anybody else notice this with their car and, if so, have you done anything about it? Any other suggestions are welcomed - especially from those who understand what causes the car to idle like that.
 
#196 ·
I am engaging a year old dead thread again, but just to add onto the records - my 2013 Elantra GLS has the same rough idling issue, its annoying. And I am wondering if engine mounts are to blame? Mechanics are hopeless!

I wish I had taken up science in school so I could become an Automobile Engineer...
 
#198 ·
My 2013 elantra gls does this as well. Noticable at stop lights occasionally and when just coming out of park. I will say from a physics standpoint that a constant vibration or possible some sort of friction will lead to a lower lifespan. Would be great to figure out the true culprit since dealers have no clue and when you take it to them it obviously isnt does not want to do it at that moment lol.
 
#199 ·
from a physics standpoint that a constant vibration or possible some sort of friction will lead to a lower lifespan
Tell that to a Harley-Davidson owner :) Even my Yamaha V Star shakes like a jackhammer, and these engines last a long time.

The Elantra's shaking issue is almost certainly normal 4-banger harmonics, made worse at random times by the smart alternator going into charging mode at idle (which it normally tries to avoid). There is no "cure" for this aside from avoiding electrical loads and red lights.
 
#202 ·
Have you noticed that the car sometimes doesn't shake on regular fuel? In that case fuel grade likely has nothing to do with it.

People keep searching for patterns to explain this quirk of the Elantra's operation, and I keep insisting that it is most likely a random event which is (a) related to the operation of the "smart" alternator, and (b) impossible to predict or cure. Someday one of us will be proven right.

:beathorse: :57:
 
#204 · (Edited)
could be a very minor vac leak, wires, pvc just for starters, always work up from simple, never assume the worst, because 9 out 10 times it's not. their is always a common denominator although it may not appear that way, like it's cold, wet, damp, hot etc. in some cases could even be a clogged cat - Ed

PS But according to the "you don't have a MAP guy", these cars don't appear to have one, or I would have said check and clean that sensor first and see what happens. if it's that annoying just do a simple smoke test. it could be just a brittle vacuum hose.
 
#212 ·
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#214 ·
I also have this problem although its on my 2011 Mitsu Galant ES (fe) 2.4. Randomly will it low idle at stoplights from to time so i will throw it in neutral & low idle quits. Curious to know what it is.

Ima assume the Chrysler 2.4s/2.0s have the same issue???

My mechanic i go to worked at hyundai/mitsubish dealership back a couple owns his own shop now. Def going to bring this up & see what he has to say
 
#217 ·
I was thinking of another element here, because I am sure we all have read this in different places and I also came across this recently and it struck me - that we often wait to refuel till the last bar left on the fuel gauge. That can also probably cause this mysterious idling.
Because even Nissan had officially released a statement to ideally refuel the cars at half tank to keep the engine smoother and for its longer life span.

So....
 
#221 ·
2011-2016) Elantra sedan/coupe > Rough Idle

I've had the same problem. Rough idle at stop, whether in park or neutral. 2012 Elantra, 27K miles. Had it in the Hyundai shop twice. Second time the regional service manager and a field rep looked at my car. Both concluded the issue is with the alternator (a known issue they say) Their response is that the alternator on most 2012-2013 Elantras is undersized for the amount of load, therefore it "pulls the engine down". I've searched all over and cannot confirm this diagnosis. The men that looked at it had the authority to do "whatever it takes" to resolve the issue and their response was, its normal...no problem....live with it. Not the answer I'd hoped for.

Still shaking
 
#230 ·
2011-2016) Elantra sedan/coupe > Rough Idle

I've had the same problem. Rough idle at stop, whether in park or neutral. 2012 Elantra, 27K miles.
I've been dealing with rough idling for my 2013 Elantra for the last 30k miles. Sometimes the whole car shakes and I can feel it in the steering wheel, others it's barely noticeable. I tried a tune out, replacing the engine mounts, scanned for codes, nothing helps. The car is up to 198k now, I'll just live with it till it blows up. which could be tomorrow or another 30k miles.
 
#223 · (Edited)
Ok so I think we are definitely on to something here. I strongly believe it's something electrical. I also strongly believe it happens more frequently with the A/C on and moreso at idle than driving. I think it may be that the alternator is TOO SMALL TO HANDLE THE LOAD. I am in the process of finishing up payments on a HIGH OUTPUT ALTERNATOR and I guess I will be the test dummy as to if that helps or not. Within the next few months I should have it installed and should have an answer for you guys just money's tight. Will keep y'all posted. Cheers!
 
#224 ·
Hey everyone I hope I can bring some thoughts I have years with Hyundai and have seen this problem With that said there is multiple causes 1: ecm update 330 late 2013 this came stock. When you update usually it poofs white smoke just drive until smoke clears 2 miles. #2 spark plugs. #3 pvc valve.#4 piston rings get carbon up and will egg shape cylinders if driven for a while misfireing, this usually is brought on by running car with green eco mode button on I dislike the eco button btw problems not a fan of sea foam but this or other professional fogs work. #5 fuel pump and ground below rear seat. Replace your ground bolts with stainless steel m10x1.00 2016 Hyundai now come this way cause myself and others complained to Hyundai long enough. Replace ground bolts in engine compartment main battery and on left strut tower. #6 low coolant in radiator. Last and least for bad idle issues is Alternator while rare I have seen this... oh and one last thought I forgot cause I have only heard not seen in your battery fuse box there is fuses that go into a small square box the box unclips and under has one connection make sure the connection looks good. I own a 13 Elantra since new the story goes 60k changed oil with full syn for the first time and wife ran in eco mode. It started getting the rough idle. It was made in 6/2013 so the 330 update was factory I put plugs in it and fogged the motor no help this usually does the trick I?m going to compression test it next hot and cold and go from there. Good luck I will update
 
#225 ·
2013 elantra rough idle

just had the same problem with the wife 2013 elantra with 45k miles. the check engine light came on, started shaking and vibrating. Had a misfire on cylinder 2, changed the spark plugs. After changing the spark plugs the car was still idling rough with the vibration being more noticible when in Park and when at stop sign or red light. Researched everywhere but no answer. Finally came to the conclusion that it was either a bad coil (which i doubted, but never know) or a clogged fuel injector. So went to walmart bought a Dura Lube Severe Fuel System Cleaner - 16 oz. Bottle $10.99, put it in the fuel tank and about 5 gallons of supreme fuel octane 91 (not regular fuel) after 3 days the vibration is completely gone. The car is running like new. Not saying that will solve the problem for everybody, but it did for me. With the elantra being a direct fuel injection keeping those injectors clean is must, I am sure adding a fuel injector cleaner every once in a while will help a lot.
 
#232 ·
Thank you































































I recently got the AirBag driver Icon and this is covered by Hyundai for 15 years I checked my Vin # and am eligible even though I am NOT the original owner .















Spread the word .



2013 elantra rough idle







just had the same problem with the wife 2013 elantra with 45k miles. the check engine light came on, started shaking and vibrating. Had a misfire on cylinder 2, changed the spark plugs. After changing the spark plugs the car was still idling rough with the vibration being more noticible when in Park and when at stop sign or red light. Researched everywhere but no answer. Finally came to the conclusion that it was either a bad coil (which i doubted, but never know) or a clogged fuel injector. So went to walmart bought a Dura Lube Severe Fuel System Cleaner - 16 oz. Bottle $10.99, put it in the fuel tank and about 5 gallons of supreme fuel octane 91 (not regular fuel) after 3 days the vibration is completely gone. The car is running like new. Not saying that will solve the problem for everybody, but it did for me. With the elantra being a direct fuel injection keeping those injectors clean is must, I am sure adding a fuel injector cleaner every once in a while will help a lot.
I noticed the 2013 Elantra 70K I just got likes the Techron as well .



When I first bought it I used Techron and premium fuel . Ran like new .



Now slightly rough Idle - maybe I need the premium fuel for a tank AND the techron .

I tried it again with regular ...



This Elantra gets great mileage [ 31 41 with ECO mode - but it drops without the additive. After a week .



With slight rough idle maybe needs both again ...

Then I will try coils .
 
#226 ·
My 2014 Santa Fe sport turbo has an excessive engine vibration when I come to a stop AND my ac is on. If I turn my AC off, it stops. Also, my interior lights blink off and on. If I shift into neutral or park at the stop, the vibration stops. Told that the small engine (4 cylinder) and turbo cause this as not creating enough power to run ac when not running. Hmmmm. So basically not fixable. I live in Kona Hawaii and ac on 365 days. Not sure what to do next , really rough vibration and started after about 2 yrs , 20,000 miles.
 
#229 · (Edited)
Hey All, I have tried numerous things I found on the net. No luck at all on the rough idle and jerking when accelerating until now.
I cleaned the throttle body and replaced my coil packs. Car is driving 100%. That is with AC on no problems.

Update: 2022-11-14
Car still running smooth without any shakes when idling. Coil packs really made a difference.
 
#231 ·
My 2011 Elantra has a slightly rough idle at stop lights. It doesn't happen ever time, and some people probably wouldn't even notice it, but at every few/several stops it idles a bit rough. When I recently had it in to Hyundai service for the ECM update, I asked them to take a look at it. Of couse, they couldn't replicate it at the time, so they couldn't do anything to address it directly. The service manager asked if it happens when the A/C is on or off. While I didn't know the answer at the time, it seems to happen with it both on or off. He did say that the ECM update may address/fix the issue, but unfortunately it didn't. While it's not a big problem, it's a minor annoyance I'd like to get fixed (as I need to enjoy my ride at all times ^_^ ).















Anybody else notice this with their car and, if so, have you done anything about it? Any other suggestions are welcomed - especially from those who understand what causes the car to idle like that.


Yes . I just got a 2013 Elantra with about 68K and it ran like a new car super smooth for two months - now just slight rough idle but I want to fix before it gets worse.

I was getting great beyond spec gas mileage and it went down and I used the Techron to get it back to 31 41 mpg .

But now the idle is getting a bit rough where I feel vibrations versus the super smooth it had before .

At 70 K - could be spark plugs ?
Will computer diagnostic show what it is ?


Yes !
 
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