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2001 Hyundai Elantra RPM problem


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oneshoeseth
Novice

Apr 20, 2015, 7:49 PM

Post #1 of 10 (2268 views)
post icon 2001 Hyundai Elantra RPM problem Sign In

https://www.youtube.com/watch?v=THv561JM_1M&feature=youtu.be

This is a 2001 Hyundai Elantra (GLS I think) 2.0L 5-speed manual with roughly 171,100 miles on it. I recently discovered this problem and replaced the idle air control valve, as well as put a new gasket in with it (there wasn't one before). I think my next step will be to replace the spark plugs. The check engine light had just come on because I was driving around without the gas cap on to see if there was a problem with the tank (there is I just thought it might also be causing this issue - cannot fill gas properly).


Discretesignals
Ultimate Carjunky / Moderator
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Apr 20, 2015, 8:08 PM

Post #2 of 10 (2261 views)
Re: 2001 Hyundai Elantra RPM problem Sign In

The reason you can't fill up your tank correctly is because the charcoal canister is faulty and allowing carbon pellets into the lines that vent the tank. You have to replace the canister and remove the carbon from the vapor lines.

The idle air control valve isn't causing your idle issues. If you notice the check engine lamp flickers right before the rpm drops. You have some sort of power or ground issue going on or the controller is being spiked by something causing it to shut off or reset. It happens pretty fast, so you may need to hook up a scope to see if the engine controller is shutting down for a fraction of a second. If you see that the engine controller is resetting, then you have to figure out why. You may need to bring it to a shop that specializes in drive-ability issues.


Leaking Hyundai canister. The foam barrier inside the canister rots away and allows the charcoal into the vapor line side. When the vent lines get plugged with pellets the air in the tank can't be displaced during refueling causing the station's pump nozzle to kick off which takes for ever to fill the tank:







Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Apr 20, 2015, 8:35 PM)


oneshoeseth
Novice

Apr 20, 2015, 8:50 PM

Post #3 of 10 (2243 views)
Re: 2001 Hyundai Elantra RPM problem Sign In

Does this seem like a problem that will most likely be costly and so I should just start looking into another car?


Discretesignals
Ultimate Carjunky / Moderator
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Apr 20, 2015, 8:58 PM

Post #4 of 10 (2240 views)
Re: 2001 Hyundai Elantra RPM problem Sign In

Can't really give you an answer on that one.

It could be something simple causing your engine issue. It is just the matter of finding the cause. If you have a drive-ability tech check it out, your going to have to pay a diagnostic fee. Hopefully the tech is proficient enough to isolate the cause in a reasonable time and with accuracy.

I wouldn't give up on the vehicle until the causes are isolated and your quoted on what it would cost to repair them. Once you have that information, you can decide what you want to do with your vehicle.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Apr 20, 2015, 8:59 PM)


oneshoeseth
Novice

Apr 20, 2015, 9:36 PM

Post #5 of 10 (2237 views)
Re: 2001 Hyundai Elantra RPM problem Sign In

Okay, I will be sure to diagnose it ASAP. Any possibility of it being something fairly simple was all the hope I need. Will keep you updated, thank you.


oneshoeseth
Novice

Apr 25, 2015, 8:45 AM

Post #6 of 10 (2197 views)
Re: 2001 Hyundai Elantra RPM problem Sign In

Update. Took it to a shop that a car-savvy friend of mine trusts. They told me that my IAC valve that I had replaced was actually faulty and had got it running fine with a new one. I was a bit skeptical at first, but it's highly possible seeing as I got it from an unverified Amazon dealer (link deleted. Contact admin for permission to use links)
I did raise concern about the possibility of it being the computer, in which case I wouldn't bother because it'd be so expensive to probably replace that. Will update on whether the problem happens again.
In total, with a diagnostic fee it is costing me around $230 which is a lot, but if it doesn't work I get a store credit.


(This post was edited by Discretesignals on Apr 25, 2015, 8:51 AM)


Discretesignals
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Apr 25, 2015, 9:00 AM

Post #7 of 10 (2192 views)
Re: 2001 Hyundai Elantra RPM problem Sign In

I don't know my friend. If the same problem was occurring before you replaced the IAC valve, I don't see how a replacement IAC could cause the same symptoms. I've have never seen a Hyundai IAC cause that kind of symptom. I've seen older Mitsubishi IAC motors short out and fry the engine controllers, but haven't seen that on later models. Not saying that can't happen, but in my opinion possibility is low.

I'm not going to say with absolute certainty that the replacement IAC would cause that, by I am very skeptical of their diagnosis. Time will tell.

Just because I stated the engine controller was possibility resetting or shutting down for a fraction of a second doesn't mean the engine controller is the problem. I did mention power, refs, grounds, and possibility of voltage spikes affecting the engine controller. Don't ever condemn a controller unless you have determine it is the fault through diagnostic testing of what it needs and the outputs that it controls.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Apr 25, 2015, 9:06 AM)


oneshoeseth
Novice

Apr 25, 2015, 9:08 AM

Post #8 of 10 (2185 views)
Re: 2001 Hyundai Elantra RPM problem Sign In

I'm just as skeptical as you are as of right now. However, when I removed the original IAC valve and cleaned it, performance did boost phenomenally. Upon further examination, the opening was stuck and it looked like upon it's rapid opening and closing that it was possibly getting stuck. The part I ordered on Amazon did fit, but looked rather generic and was only confirmed in a short comments section whether it fit on my car or not, as oppose to an Amazon verified seller.
I will know probably within a day or so whether the IAC valve is the cause. Your help is extremely appreciated - they seemed certain that that there were no such other issues, despite my showing them that the check engine light would flicker.
Another thing to note, the day it started acting up (last week roughly) it was raining. Which I did tell them, also.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 25, 2015, 10:05 AM

Post #9 of 10 (2179 views)
Re: 2001 Hyundai Elantra RPM problem Sign In

Just noted that you said the day it acted up it was raining? That's high time for electrical anything to act up, connections and grounds get weak and a signal doesn't get thru. If just wet induced many things will quit it when dry again - maybe?


Another: Flickering Check Engine Light or equivalent now? That's another that is probably part of a problem that may still exist?


If wet induced like that sometimes spraying a mist a slightly salted water on connections might cause it to reoccur right away for you and know that's a real reason. Just thoughts as if DS says that isn't the likely fix and now wet was an issue was thinking of those gremlins,


T



oneshoeseth
Novice

Apr 25, 2015, 12:43 PM

Post #10 of 10 (2171 views)
Re: 2001 Hyundai Elantra RPM problem Sign In

Just got it back from the shop. So the problem on the first IAC valve was that the actual port where it would open and close would get stuck open, as seen when it was removed. I bought another via Amazon (link earlier in the thread) and apparently when inspected while running it would buzz consistently. After replacement, the new and now third IAC valve I have come into contact with does not buzz and seems to work more than adequately (thus far). It was test drived by the technician in dry and wet conditions, with no problems whatsoever, leading me to conclude that as of now it is not electrical. The problem with the second can only be concluded as an internal problem, and therefore I will be contacting the seller and returning it (and leaving a bad review). I am grateful for all of the help and hopefully this is the last time I will have to visit this particular thread. Total cost, with diagnosis = 88.75 + 146.55 = 235 dollars total.
Moral of the story. Don't buy the cheapest IAC valve, buy the Amazon verified one or at least make sure it does not "buzz".






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