Rough Idle

[Don67]

Originally Posted by seamsealer

A little research and the (ECR) valve (exhaust gas recirculation) could have some vacuum problems or maybe some carbon from the exhaust which is recirculated for emissions.

That doesn't explain why the problem is random and intermittent, and seems to affect so many Elantras. My money's on Jeff's theory.

[Aaron.H]

Originally Posted by someguy

Wow old thread here. This issue seems to have worked itself out over time for me. I guess the engine just needed to completely break in or maybe I just don't notice anymore.

well for the first time in my car's life....42,750km.....all of sudden after filling the E up....was really backed up traffic...standstill tbo. after 1 KM of creeping on and off breaks......didn't get a look to see if was rough idle but came from engine and started shaking entire car..... so i shut off the car and turned back on...nothing so after another 0.5km in same traffic as im creeping this time not fully breaked. it came back but not as worse but than went away within 3 seconds and heard the compressor or fan turn off..... so not sure what exactly caused this but this is a first ever on my E...maybe from the snow and salt.... i took off probably at least 2 ice cream buckets full of ice/snow/salt/crap for each wheel well so aybe had some stuff jammed up in my engine bay.....been minus 5 for last week and finally -12 today and had the big snowstorm saturday/sunday whci had to plow through everywhere

[seamsealer]

Originally Posted by Don67

That doesn't explain why the problem is random and intermittent, and seems to affect so many Elantras. My money's on Jeff's theory.

My idle problem is not random. When warmed up and in D or R, there is a rough idle, it can be felt while in the car. The ECR has a piston and is subject to exhaust gases and can foul. Some say a good cleaning can fix the problem. Time will tell.

[LoeCraw]

Originally Posted by Don67

That doesn't explain why the problem is random and intermittent, and seems to affect so many Elantras. My money's on Jeff's theory.

It's a good theory, but not sure if it applies to me. I've noticed that when I do experience a rough idle, I can put it in neutral (or park) and it completely goes away. I would think that that if it was extra drag on the engine due to the alternator, than it would happen regardless of which gear it was in. Thinking maybe it's the "pull" of the transmission -like the torque converter is more excited than normal, haha.

[Red Allure]

I've had this rough idling a few times. It's almost as if the car will stall but doesn't. I just make sure to hammer it so as to "blow out the carbon" and that seems to do the trick for a while.

[ric77447]

Mine does this to, not all the time but sometimes I come to a stop sign and it idles rough, doesn't matter if a/c is on or off. I was just going to post something when I saw this thread.

[seamsealer]

Originally Posted by ric77447

Mine does this to, not all the time but sometimes I come to a stop sign and it idles rough, doesn't matter if a/c is on or off. I was just going to post something when I saw this thread.

That is exactly what I get most of the time. P or N and its smooth as glass. Put it in gear and it's rough. I have 32,000 miles and it's a 4cyl. I may take it in next week and see if they can pin point the problem. My wife's 09 Santa Fe makes no difference at all, in gear or out, you can't notice any difference. A friend of ours has a new Sonata and it isn't rough either.

[Don67]

Originally Posted by LoeCraw

It's a good theory, but not sure if it applies to me. I've noticed that when I do experience a rough idle, I can put it in neutral (or park) and it completely goes away. I would think that that if it was extra drag on the engine due to the alternator, than it would happen regardless of which gear it was in. Thinking maybe it's the "pull" of the transmission -like the torque converter is more excited than normal, haha.

Not sure that invalidates the theory. Putting the car in neutral takes some of the load off the engine, which has a calming effect no matter what else is happening.

Just sayin' that the intermittent nature of the condition (for most of us that is, seamsealer) is most logically explained by the intermittent operation of the smart alternator.

Someday we'll get official confirmation of this great mystery.

[Jeffs2011SonataSE]

Originally Posted by seamsealer

At my last oil change, first one for me with this car, they said it was normal when you put it in drive. I call BS. There should be no difference between neutral and drive.

This is incorrect. There is a difference between the two and its totally understandable. Here is why. When the car is in park for one, the idle general bumps up slightly, usally 150-200rpm higher, this alone smooths out the idle. This comes into 2 and the reason why 1 happens. When you move the Lever to Drive, or D, the load of the engine transfers to the Transmission causing an RPM drop. Why? Because the car is anticipating you to GO. When you hold the car up, by pressing on the brakes, the vacume pressure alone used to use the brakes even can cause an RPM drop ever so slight. So to say there is no difference is not correct. I wish I could explain it better, but its completely normal for Idle to change when going from P to D. What I am talking about, is idle flucuation at idle that makes the car shake a little. I am still learing about this "Smart Alternator" and I do feel it does indeed come on at idle. I don't think its a "fixed" time. When the ECU reads that Voltage drops at any given time the "Smart Alternator" kicks in, regardless if your at idle or not. I am still researching this.

There are many reasons for rough idle: Poor quality gas, outside temp, A/C on or off, Smart Alternator, Faulty Coil Pack, Throtle Body is Carboned up, bad engine or tranny mount, I mean I could go on and on...Most likely though since these cars are new, and the engine is newly redesigned for this new Elantra, it could just be a trait of the car period. All Engines have their "Traits".

So do some work yourself. Keep an eye on your MPG's because that is a good indicator about how well a car runs. If your getting 26mpg's when you usually get 33 that says something. If you step on the gas and it just doesn't take off right, you know? Those are indications of something more serious. Sorry if I got off point......

Jeff

[seamsealer]

Jeff, I understand there is a small drop in RPM between N and D, but there should not be any rough idle. You can't even feel a clunk or anything when going from N to D. I am too old and have owned too many cars to know this is not the norm. If Hyundai made all their cars this way and told people it was normal, they would go out of business, no one would buy one.
My wife has an 09 Santa Fe and there is no difference between N and D.
I need to make an appointment and take it in. My friends with their Fords and Chevys rag on me because of the idle. I got to get it fixed. LOL