Author Topic: Jumpy idle on accelerator release  (Read 1948 times)

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  • wales Wales
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Jumpy idle on accelerator release
« August 24, 2013, 02:17:25 »
Morning all!

Ive started to settle into the way the i30 runs now I've had a few months, and can honestly say its a great car.

BUT.... a few things are niggling at me and I just wanted to hear some thoughts, or whether other people have had the same issues at all?

Ive noticed that when I am doing a steady 30 or 40 MPH & release the accelerator when approaching a set of lights or junction, without dipping the clutch & let the engine resistance slow me down the engine jumps/jolts as if it is trying to stabilise an idle speed, but it carries on to jolt until I dip the clutch to bring the revs to 700, then when I lift the clutch again its fine, running around 1300-1500RPM, gradually lowers as it slows as normal, sometimes its that extreme, I worry about the engine mounts coming apart :p

Ive never had this issue with any other vehicle Ive owned, & was wondering if anyone else has had the same issue where it doesn't smoothly go from active to idle/braking?

Also, the cruise control can sometimes not find a steady settled speed/rev. I will set the cruise for 70MPH but when I do it will sometimes constantly try to find the right settled speed/rev, and I can feel it constantly speeding up, slowing down, speeding up, slowing down etc. (the speedo doesn't move & sits at 70 the whole time) other times its fine and will sit steady for a smooth and comfortable ride, this happens on flat straight roads, not a hill in sight, which would explain it trying to even the speed...

Its a 1.6 CRDi, manual active, has anyone else had anything that sound similar or the same at all? I thought it might be interesting to see whether its an isolated issue or its 'one of those things' with Hyundai's.

Thanks all!
Chris


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  • gb United Kingdom
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Re: Jumpy idle on accelerator release
« Reply #1 : August 24, 2013, 03:29:36 »
We used to call that "hunting".

Similar problems, get a load of this lot:-

https://www.i30ownersclub.com/forum/index.php?topic=18716.0

It seems spurious information into the CAN bus system, they changed the throttle position sensor, air mass, cruise control, fuel filter & lines, at one point had exactly the same problem - sometime during the last 2 years......

Still a brilliant car though, love it, hope you get it fixed :undecided:
« Last Edit: August 24, 2013, 03:57:29 by Interphase » »

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Re: Jumpy idle on accelerator release
« Reply #2 : August 24, 2013, 05:44:07 »
I've no idea about the Cc "fault", but regarding the first issue I would definitely try an ECU reset as it's the simplest and cheapest thing to try.

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Re: Jumpy idle on accelerator release
« Reply #3 : August 24, 2013, 08:12:46 »
Re cc

I have cc and depending on the selected gear and speed mine surges and drops continuously.

Asked at dealers and told it was to do with the ecu having to alter fuel intake to maintain selected speed.

As an example

At say 55 mph in 6th it surges then drops then surges then drops etc.
Drop to 5th and it becomes smooth.


If i increase speed to say 70 mph in 6th then i get a smooth ride.

Is this what you mean?
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Re: Jumpy idle on accelerator release
« Reply #4 : April 08, 2014, 21:44:27 »
This is exactly the problem, to which I did the same as yourself & conquered the issue, too high a gear for the CC to run. Dropped down one & smooth as a baby's bum! :-)

Thanks for the replies all!

Re cc

I have cc and depending on the selected gear and speed mine surges and drops continuously.

Asked at dealers and told it was to do with the ecu having to alter fuel intake to maintain selected speed.

As an example

At say 55 mph in 6th it surges then drops then surges then drops etc.
Drop to 5th and it becomes smooth.


If i increase speed to say 70 mph in 6th then i get a smooth ride.

Is this what you mean?
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Re: Jumpy idle on accelerator release
« Reply #5 : April 08, 2014, 21:50:53 »
I have no idea if it related at all, but it sure feels like it. The i30 had to be  towed to the garage yesterday due to the engine cutting out constantly, it would almost do what I said above & cut out. Especially when going around roundabouts and tight turns it would cut.

EML came on & RAC had to plug the magic machine in, wi a fault as long as my arm showing, but all I can remember is something to do with the fuel pump injector - fault.

I am assuming this is a fault with the fuel pump, where the force of going around bends or high increase in g force moving the fuel, the pump could not continue with the 'pumping' operation or the injectors were starved of fuel...?

It just seemed very coincidental that it was jumping/jolting a lot anyway then this fault appears...?

Anyone else at all?

They have provided me with a 1.4 unleaded base model, which has about the same punch as a hair drier haha. Diesel is louder, but my god what a difference in engine performance! Outstanding Diesel engines by hyundai! Just a shame it's in fault :(

We used to call that "hunting".

Similar problems, get a load of this lot:-

Limp Home Mode

It seems spurious information into the CAN bus system, they changed the throttle position sensor, air mass, cruise control, fuel filter & lines, at one point had exactly the same problem - sometime during the last 2 years......

Still a brilliant car though, love it, hope you get it fixed :undecided:
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Re: Jumpy idle on accelerator release
« Reply #6 : April 09, 2014, 00:43:07 »
Buggy fuel?
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