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95 Hyundai Elantra Idle Speed Problems
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calimer
New User
Jan 27, 2010, 4:06 PM
Post #1 of 5
(5762 views)
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95 Hyundai Elantra Idle Speed Problems
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Hi, and thank you to anyone who reads this and even considers helping as it has been an ongoing problem for a while, and lots of money later it is still a problem.
The car is a 95 Hyundai Elantra GLS with around 80k miles. I generally only drive it to and from work which is only a few miles.
Here are the main issues:
- Sometimes the idle speed seems too high. I have to fight to keep it stopped and sometimes even when first applying the brake it will jerk forward a little. Sometimes it is fine, especially if the car is cold or it is literally really cold out, but the warmer the car is the worst it seems to act up, sometimes to scary levels.
- When I coast sometimes it feels like the car is grabbing and jerking
- The car sounds like it is revving in park, happens a lot more frequently when parking than when starting the car. It also sounds like it is shutting off hard.
- The check engine light comes on sometimes briefly 1-30 seconds (though this seems fixed after they did a fuel induction service).
The problems all seem related as well, when the the idle speed seems to be normal, there is no jerking and generally no revving when I place it in park. However, depending how loud the idle speed is when I turn it on is a good indication of how rough of a trip home it will be. The louder the worse the trip.
What was done and has not fixed the problem:
- Idle speed screw was adjusted
- Fuel Induction system service
- New Idle Speed Control Servo Kit
They say that if it isn't that, it must be the computer. However, my main Mechanic thought it might be the air intake valve (which I think is the same as the AICV) or the computer but he doesn't do that kind of service. I read a post online where a guy with a toyota or something had a similar problems, but not exactly the same, and cleaned the AICV and it fixed the problem. It seems like it would be relatively inexpensive to have them clean the AICV though I don't know if it is the proper solution, and also it seems like they should have considered that first, especially since I had a written note to them saying the previous mechanic though it was the air intake valve, and replacing that idle speed control servo kit was a lot of money.
Any thoughts and suggestions would be greatly appreciated. Thank you so much for your time!
-mike
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jan 27, 2010, 7:13 PM
Post #2 of 5
(5749 views)
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Re: 95 Hyundai Elantra Idle Speed Problems
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Mike - most injected engines don't have an idle adjustment. It's a base setting if there's one and really shouldn't need to be touched.
This may be (not sure how throttle is done) a cable issue or throttle plate that doesn't allow it back to idle. Cable if done that way can fray and pivots for throttle can be sticky. Just glance with engine off and a helper to hit gas pedal and watch what moves at throttle body. Then see if by hand it can be moved further to what would be a lower idle. If so I'd say it's plain mechanically sticky or fraying cable wire - a guess without being there,
T
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Sidom
Veteran
/ Moderator
Jan 27, 2010, 7:27 PM
Post #3 of 5
(5746 views)
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Re: 95 Hyundai Elantra Idle Speed Problems
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Well is sounds like you have an intermittent idle problem that could be with the IAC valve or false air (vacuum) as far as a bad PCM, while not impossible I just haven't seen a lot fail on Hyundai's, it is pretty rare..Now if this was a Chrysler, that would be a different story...
FYI there is no idle adjustment screw on a Hyundia, Yes there is a screw on the throttle body that you CAN change the idle with, but that's not it's purpose and if the base idle isn't set correctly with that adjustment screw it can actually make things worse.
You can do the things you mentioned 1st, cleaning the IAC & throttle body, check for vacuum leaks (check around the intake real good) make sure the intake tube isn't split or any holes in it, all this would be good to do. If all this checks out the best advise I could give you would be to take it to a shop that is equipped & trained to handle this. They won't be the cheapest and for a good reason, they have invested a lot of money in the proper diagnostic tools & training and that isn't cheap..
I can only go off what you have posted but from what I've seen it sounds like they are guessing at the problem and have thrown some parts at it in hopes of fixing it. The proper shop for this problem will be way more expensive as far as diagnostic charges go compared to the other shops but in the long run, for this problem could wind up being cheaper in the end.
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calimer
New User
Jan 27, 2010, 9:43 PM
Post #4 of 5
(5739 views)
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Re: 95 Hyundai Elantra Idle Speed Problems
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Thanks so much for the help with this! I should have mentioned the full story as well. This complication started when I was driving and about 2-3 miles into my trip, I was stopped at a traffic light and my car made strange sounds (sounded like the idle having problems) and then it just died. After some time passing, about a half hour or so of trying to get it to work again, it turned on again and then died again at the next intersection. I had it towed to my mechanic who said that the idle speed screw was too tight and he adjusted it and made things work again. It is ever since then that the car has been overzealous. Then I brought it in to this place and they cleaned the throttle out and the car seemed to run fine. Then my car battery died not too long after that (it was about 4-5 years old) and installing the new battery brought the problems back. I'm not sure if that helps enlighten the situation anymore.
And you're right, they are throwing parts at it and that is what they told me. I guess their diagnostic equipment only goes back to 96 Hyundai's. I did bring it to them because they are supposed to specialize in that, which is why I have been paying some nice cash, over about $500 now for all of this. Sounds like it is time to bring it somewhere else. I did pay about $80 an hour for this place for diagnostics alone (which obviously didn't seem to be worth my $$) but when you are talking about way more expensive, are you talking a lot more than that, or is that the more expensive price?
Thank you so much for your help! Take care.
-mike
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Sidom
Veteran
/ Moderator
Jan 28, 2010, 1:16 PM
Post #5 of 5
(5726 views)
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Re: 95 Hyundai Elantra Idle Speed Problems
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The idle adjustment could be part of the problem. In short that screw is for a base idle adjustment, just guessing say around 400 rpm. The computer expects this adjustment to be there and all the adjustments it makes goes off of this. It has no way of knowing if it's been changed & "trusts" it's where is should be. If it's not that's when you can get some problems. One of the things the idle on Hyundais will do is surge or "hunt" when in park but be fine in drive when this adjustment is off.
That's one thing that makes diags a little tougher is when someone has gone in who isn't familiar with the system and changed things that should've of been changed trying to compensate for a problem. The 1st thing that needs to be done is all the adjustment that were changed need to be set back to factory specs. Then mechanical & electrical area of the engine need to be confirmed as good, once again a computer can't tell if there is a mechanical problem with the engine. All it can do is see the skewed readings from the input sensor & try and compensate for the readings as best as it can within it's allowed parameters.
Actually you're pretty much in the ballpark for what you should be paying for a good diag, at the low end but in range. I was referring to shops that don't put out money for tools or training, a lot of times they will offer "free diags" or at a very low price due to no overhead and basically just reading the codes & guessing at the problem so there is no real time involved other than preparing an estimate for repairs...
I wish I had an exact formula for finding the "right shop" but don't. The 1st red flag is the free diag for reasons mentioned earlier. The are a couple of automotive sites for technicians, ASE & iATN.net that have shop locators on them, any shop associated with these sites are at the minimum trying to keep up with the technology. Sometimes talking with friends, work associates, neighbors see what problems they've had and who they have had a good experience with helps. Even things like if the shop is doing things to support the community is a good sign.
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