Author Topic: Car idle fluctuates, any ideas mechanics?  (Read 4048 times)

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  • gb United Kingdom
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Car idle fluctuates, any ideas mechanics?
« March 04, 2018, 14:47:49 »
Hey guys, I have a Hyundai i30 2011 Hatchback CRDi on 70,000 miles. Sometimes when it's on D at the traffic lights, I noticed the rpm start's to go down but not a lot to the point where it turns off and then it brings itself back up. I noticeable. Recently I had the fuel filter changed and it was genuine part. Any idea what it can be? I wish I can take a video but it's happens unexpectedly. Also, another thing when its cold it takes a bit of time. More than my friends toyta yaris. What could it be? I am suspecting a bad glow plug? How much would it cost to replace all 4 by the deal? Any estimations? Any idea what this can be about if its not the glow plugs?
Thank you


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Re: Car idle fluctuates, any ideas mechanics?
« Reply #1 : March 04, 2018, 15:00:06 »
Idol dropping slightly at lights sounds like the thermo fan cutting in (normal)

When you say "when it's cold it takes a bit of time" do you mean getting to operating temperature? you have a diesel so they naturally take longer to warm up if this is your concern.

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Re: Car idle fluctuates, any ideas mechanics?
« Reply #2 : March 04, 2018, 15:03:48 »
 :welcumwagon:

I don't think glow plugs affect the idle once it is started (although I could be wrong)

Assume you mean bit hard starting when cold (which could be the glow plugs)

Unless the dealer has trouble getting the old ones out changing the glow plugs shouldn't be an expensive job.

I thought a set of 4 was about A$100 but these are much cheaper!

:link: 4 X KIA CEED PICANTO RIO SOUL 1.5 1.6 2.0 CRDI Glow Plug | eBay

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Re: Car idle fluctuates, any ideas mechanics?
« Reply #3 : March 04, 2018, 15:05:29 »
Quote from: billy638
... when it's on D at the traffic lights, I noticed the rpm start's to go down ...

Can you try nudging it into N and see if there's still some fluctuation?
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  • gb United Kingdom
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Re: Car idle fluctuates, any ideas mechanics?
« Reply #4 : March 04, 2018, 15:11:17 »
What I meant is the car it takes a long time to crank, in cold condition. I know this is normal, but not when it's -2 right? Also, the other day the cranking sound would stop then crank continuously, until the car started if I remember it was -2c outside. Is that normal too? Also shambles I'll check tomorrow what happens when I put it into N. But say it does fluctuate in N, what does that mean? Thanks guys
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Re: Car idle fluctuates, any ideas mechanics?
« Reply #5 : March 05, 2018, 00:31:22 »
You need new glowplugs, thats all. They also help against rough running after startup when the engine is cold.

Replace all 4. If doing it yourself, the engine must!!! be warm, as this significantly reduces the chances of breaking them while loosing them  :winker: