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Discussion Starter #1
In short.
At idle (car is parked, no load on the engine) the engine runs at about 650 RPM.
When I tap the gas - it reacts OK. Engine quickly speeds up.

However, when I want to gently, slowly increase the engine speed - say I want to reach 1000 RPM - it will not respond until a moment when it jumps up to 2500 RPM. Then it might decrease a little, but it is almost impossible to set it at 1000 RPM. I even tried to move the gas pedal with my hand.

One note.
It is Elantra HD (2009) with stick shift.

I posted it here as I get no responses in HD forum whatsoever... over 50 views and nothing (http://www.hyundai-forums.com/193-h...dal-too-sensitive-cant-maintain-1000-rpm.html).
Hence, I thought I would ask here. Maybe some MD owner had HD before...

So could anyone say how their cars respond? I am also curious how GTs handle it.
 

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so there is some kind of delay when your car should be adding more fuel...it isn't right away. there's a lot of things that can be causing this behaviour, so its hard to say. probably why nobody replied to your first post.

i can give some general thoughts, but more info is needed for a diagnosis. first thing: check engine light? the ECU should be checked for codes regardless.

i'd start by looking for any vacuum or air intake leaks. could also be a delay in the TPS. as suggested by another member in another thread, try unplugging the TPS. yes the car will run like ass, but see if the delay is gone. if it is then its likely the TPS.

also check your connections and wiring.

with a 2009, any warranty left?
 

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Discussion Starter #3
Thanks for the first response.

No CEL
No codes - no stored, no pending (ScanGauge)
Yes, still under warranty.

Well, what I want to only hear is IF you can gently move the gas, or rather if you can slowly increase engine speed. 650, 800, 100, 1200... and so on.
On mine - no matter how I do it - 650, 2000.
Tonight I will shoot some video of it.

It is not the delay of ECU. I know that from 2007 KIA Rondo (TPS/ECU plus fly by wire...) and it responds with some delay, but it does it in more gently manner.
 

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so there is some kind of delay when your car should be adding more fuel...it isn't right away.
I've noticed the same thing, to a lesser extent with my Elantra.
It is noticeable ONLY when not actually moving so I chalked it up to a "computer thing".

IF it does the same thing when actually moving, it might be an intermittent Throttle Position Sensor.

You just think it is you that is controlling the engine speed; it REALLY is the computer !! :D

[edit]
Sorry if that was not what you wanted to hear.
No, mine is not really smooth either but it doesn't jump THAT far.
 

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Discussion Starter #5
IF it does the same thing when actually moving, it might be an intermittent Throttle Position Sensor.
I was hoping you were right...
I hoped...
I just drove it, rolling like 10-15 MPH and the only difference was the idle speed. Instead of 650 it is 830 or so. The rest, reaction to the throttle was same. Jump from 830 to 2000. Over 2000 RPM it is smooth. However, between 650 and 2000 I can't get the speed to set (no load to the engine - in neutral).

You just think it is you that is controlling the engine speed; it REALLY is the computer !! :D
I HATE that.
 

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I just drove it, rolling like 10-15 MPH and the only difference was the idle speed. Instead of 650 it is 830 or so. The rest, reaction to the throttle was same. Jump from 830 to 2000. Over 2000 RPM it is smooth.

However, between 650 and 2000 I can't get the speed to set (no load to the engine - in neutral).
I just read that 5 times.....and still don't understand.

It looks like the problem is almost exactly the same whether standing still or moving.....but then there is that last sentence starting with "however". What's the "however" part; looks the same to me.

So that brings us back to the TPS; either way you have convinced ME that it's a warranty item, if you still qualify. Alas, convincing ME means almost nothing. :(
 

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Have you had a look in the throttle body? Is it clean and clear of buildup, particularly at the plate hinge? The IAC pintle could be sticking at that certain range too. It may be able to be cleaned.
 

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It's more than likely a dirty throttle body, removing the intake tubing assembly and with the engine off of course, open the throttle blade by hand and clean the area it normally rests with a microfiber rag and some seafoam will probably solve the problem.


Most modern DBW (Drive By Wire) systems no longer use an IAC (Idle Air Control) valve because the computer simple modulates the throttle blade to adjust idle.

*Edit but leaving my info* looks like this model does still use an IAC valve, weird...

A cleaning of the IAC, throttle body, and MAF sensor would probably help, all can be done at home by anyone fairly mechanical and understanding of modern autos.
 

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Discussion Starter #10 (Edited)
I just read that 5 times.....and still don't understand.

It looks like the problem is almost exactly the same whether standing still or moving.....but then there is that last sentence starting with "however". What's the "however" part; looks the same to me.
That refers to part talking about RPM over 2000 being smooth region. However, below 2000 (650-2000) can't set the speed.
Sorry for the confusion.

it's a warranty item, if you still qualify.
Yes, I do qualify. Still one year left... I have had this car for about 9 months now so I start seeing some new things over the summer.

Have you had a look in the throttle body? Is it clean and clear of buildup, particularly at the plate hinge? The IAC pintle could be sticking at that certain range too. It may be able to be cleaned.
All is clean. I did not remove TPS (let Hyundai play with it).
Thanks for the suggestions.

But again, I do not quite look for a solution, although that would be nice to have one. I want to know if other Elantras do the same.



When you look on the first video


Begins at about 0:07
See TPS?
I push the gas, TPS reads 5, then 6 degrees and no change. Finally, within still 6 degrees RPM jumps to 2000 and TPS changes to 7. I try to lower RPM, TPS drops to 6, no change, and finally, RPM drops back to idle. TPS still 6. And finally when I completely released the gas it is back at 5.
Confusing to me...
 

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throwing junk like seafoam into it and cleaning isn't going to help a delay like this. it would cause a restriction in the TB, loss of power, etc. but this is an instrumentation problem. lets focus on diagnosis shall we?

without error codes, its difficult to say...not many clues. to start with this would be my approach:

- disconnect battery for 20 minutes, let the computer reset any of your learned behaviour.

- check sensors for any buildup.

- check for vacuum leaks and any air intake leaks.

- you have a warranty. use it.

furthermore, have the stealership check if your ECU is up to date. never know, this may be a known/fixed issue already.
 

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Discussion Starter #12
throwing junk like seafoam into it and cleaning
not gonna happen :)

- disconnect battery for 20 minutes, let the computer reset any of your learned behaviour.

- check sensors for any buildup.

- check for vacuum leaks and any air intake leaks.

- you have a warranty. use it.
All sensors are clean. Intake is tight without any visible leaks. I did not bother to check with starter spray, but I doubt there is any leak since everything seems to be fine (it starts right away - cold or hot, no rough idle, will keep speed under load - A/C, blower, heater, lights...).

I am going to use warranty, probably next week.



I will repeat the question:

DOES your car react same?

That's pretty much the only thing I want to know before I go to the dealer who might say:

Oh yeah, all of them do that.

Will it be BS? I want to know before going there.
 

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Discussion Starter #14
In case it was lost in the "smoke":

yes.
But not nearly as bad.
It was not, and you are the only one who said that. Everyone else is trying to troubleshoot it, for which I am thankful, but it does not help me so much.

If I get more than three same responses I can start believing it is normal...
 

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Has to be a glitch in the throttle cable or linkage somewhere. Have you lubed it? Your car is an HD so maybe the HD group can give you more accurate help.
 

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Has to be a glitch in the throttle cable or linkage somewhere. Have you lubed it?
It is clean, moves and slides with no problem. I do not find any mechanical issues whatsoever. For safety I added a few drops of oil to the cable, but no improvement. No restrictions can be felt by hand or foot.

Your car is an HD so maybe the HD group can give you more accurate help.
I tried... no response and I had posted the question more than a day before posting it here.
 

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Tough problem to solve in this forum, given the difference in technologies (2.0 Beta engine vs. 1.8 Nu, cable throttle vs. electronic, etc.).

Might want to try Edmunds or something else with a wider reader base. The answer could come from anywhere, not necessarily Hyundai.
 
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