Author Topic: Jerky acceleration  (Read 2957 times)

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  • dk Denmark
Jerky acceleration
« May 08, 2019, 13:35:48 »
Hello everyone,

I just got a Hyundai i30 and it has an issue with acceleration.

In the morning  when i drive to work it accelerates as it should with no issues.

When i am leaving work it starts to accelerate erratically.  As i drive away it acts like i am  punching the gas pedal and letting off.  The effect is so much that people have  looked and likely wondered why i was driving that way. It seems to go away after about 3 to 4th gear. One day it did this issue slightly all the way home in all gears.

During this my foot is on the gas pedal and all else seems normal.

The car is a 2011 manual diesel with 150,000 km. I just took the car to get a fuel line cleaning and the fuel filter change thinking it could be that but its not helping.

I have connected a WOW odb computer and all systems from car pc are green with no failures.

Does anyone have any suggestions as to what might be causing this?

Thanks,
Mat


  • 2011 Hyundai i30 crdi 90 blue drive

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Re: Jerky acceleration
« Reply #1 : May 08, 2019, 18:43:29 »
 :welcome: Mat,

Sorry to hear that! I'm not one of the "tech heads" on here but it sounds like it's temperature related.

I can understand you also suspecting fuel filter/fuel line issues. Good to rule that out.

Hopefully our friendly helpful (more mechanically minded) members will help you narrow down the suspects.
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Re: Jerky acceleration
« Reply #2 : May 10, 2019, 23:38:48 »
If you have data record in the obd reader it might be good to record rail fuel pressure and throttle position and see how they behave when accelerating. There have been few times when people had got cracks in the fuel filter heater element. It has sucked air in causing drop n the fuel pressure.

I had issues with 3rd party filter. It was not flowing correctly and caused limp mode due low fuel pressure. Fixed it with OEM filter.
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Re: Jerky acceleration
« Reply #3 : May 12, 2019, 11:06:34 »
The rapid surging also has me thinking that your turbo boost is fluctuating.

A number of things can cause this, but a commonly hidden problem ( intermittent and temperature conscious) is a fractured hose going to the turbo actuator. 

take engine top cover off and you will see them.
« Last Edit: May 14, 2019, 03:10:49 by nzenigma » »
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Re: Jerky acceleration
« Reply #4 : May 14, 2019, 01:05:24 »
Thanks everyone for your leads. Yesterday i removed the fuel pump within the tank and found lots of gunk stuffing up the sieve so i was happy to get that all cleaned up. 

I thought i would post these pictures for others wondering about the internal pump.

Ill dig deeper into the leads you have posted and when the solution is discovered, ill come back with a new post.







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Re: Jerky acceleration
« Reply #5 : May 14, 2019, 01:10:39 »
Could be a bit of diesel fuel bug there. I'd be adding a fuel bug additive. I don't know the best one, but someone will.  :cool:

https://www.google.com/search?q=diesel+fuel+bug+treatment&oq=Diesel+fuel+bug+&aqs=chrome.1.69i57j0l5.15059j0j8&sourceid=chrome&ie=UTF-8
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Re: Jerky acceleration
« Reply #6 : May 14, 2019, 03:20:39 »
No 'could be', it IS bug.

Curiously, we have recently been discussing the tank pump. Australian i30s dont have them.

But we do have the bug if it is a badly stored fuel supplier. Try to buy from a well used outlet.

You will see tiny jelly like creatures in your fuel if it is active. If so clean the tank out completely. Even if clean, treat new load of fuel with double dose of additive.

The one I use is Liqui Moly (for diesel fuel).
« Last Edit: May 14, 2019, 03:28:01 by nzenigma » »
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Re: Jerky acceleration
« Reply #7 : May 14, 2019, 03:27:36 »
Shame about the issue, great images though. definitely will be more than cleaning just that filter, whole tank would be slimy I think
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Re: Jerky acceleration
« Reply #8 : May 15, 2019, 00:59:11 »
@mat2219

I Should have reminded you to replace your fuel filter. It will be full of gunk.
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Re: Jerky acceleration
« Reply #9 : June 03, 2019, 15:22:31 »
Hi, is the fuel filter heater element the black portion of the filter housing, just above the filter with a sensor wire?
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Re: Jerky acceleration
« Reply #10 : June 03, 2019, 15:26:06 »
Hey, I have replaced all of the fuel return hoses from injectors and also the one hose that goes to the turbo near the top. Is the actuator the round part that sits on top of the turbo?
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Re: Jerky acceleration
« Reply #11 : June 03, 2019, 16:29:40 »
Hey, I have replaced all of the fuel return hoses from injectors and also the one hose that goes to the turbo near the top. Is the actuator the round part that sits on top of the turbo?
The Turbo is variable vaned and the adjustment is via a vacuum canister and that hose is a vacuum hose.
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Re: Jerky acceleration
« Reply #12 : June 15, 2019, 14:49:20 »
Hey guys the mystery has been solved.

I tested the egr valve with a voltometer and found that it had a voltage rating that was low compared to what it should have been. I replaced it and now the car doesnt do the hestitation or hiccups anymore!

Hope this helps those who also experience this issue.

Cheers
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Re: Jerky acceleration
« Reply #13 : June 15, 2019, 17:18:32 »
Hey guys the mystery has been solved.

I tested the egr valve with a voltometer and found that it had a voltage rating that was low compared to what it should have been. I replaced it and now the car doesnt do the hestitation or hiccups anymore!

Hope this helps those who also experience this issue.

Cheers

Excellent. Thanks heaps for getting back to us with an update.  :goodjob2: :goodjob:
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Re: Jerky acceleration
« Reply #14 : June 15, 2019, 17:28:32 »
:whsaid:
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Re: Jerky acceleration
« Reply #15 : June 15, 2019, 18:02:16 »
Hey guys the mystery has been solved.

I tested the egr valve with a voltometer and found that it had a voltage rating that was low compared to what it should have been. I replaced it and now the car doesnt do the hestitation or hiccups anymore!

Hope this helps those who also experience this issue.  :goodjob2: :goodjob2: :goodjob2: :goodjob2:

Cheers

Excellent. Thanks heaps for getting back to us with an update.  :goodjob2: :goodjob:

 :thanx:  :whsaid:

The surging symptoms and evidence of bug did not lead me to think of EGR.   :-[
 Although, Im reasonably sure the fuel blockage did contribute.

I see this as another really valuable piece of information contributed by ( as usual) an i30 OWNER.  :wink:






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Re: Jerky acceleration
« Reply #16 : October 08, 2019, 11:51:00 »
Hey guys the mystery has been solved.

I tested the egr valve with a voltometer and found that it had a voltage rating that was low compared to what it should have been. I replaced it and now the car doesnt do the hestitation or hiccups anymore!

Hope this helps those who also experience this issue.

Cheers

This seems to be a reasonably common issue with the sister model, the KIA Ceed.

I get the same symptoms starts and runs fine but if I do multiple starts that's when you get that "kangarooing".

Flooring the car solves the problem but cleaning/replacing the EGR valve seems to be the solution.

Was your EGR easy to change?
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Re: Jerky acceleration
« Reply #17 : November 16, 2019, 18:31:13 »
Hi everybody,
I have just bought a 2 year used i30 PDu ... and have the hesitation syndrome :(
1200-1250rpms  precisely (not kangaroo, just hesitation in that range)
It is more evident with increasing load or on steep hills but once over that rev range it is ok

The car only has 2000Km on the clock
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Re: Jerky acceleration
« Reply #18 : November 16, 2019, 19:28:56 »
Hi everybody,
I have just bought a 2 year used i30 PDu ... and have the hesitation syndrome :(
1200-1250rpms  precisely (not kangaroo, just hesitation in that range)
It is more evident with increasing load or on steep hills but once over that rev range it is ok

The car only has 2000Km on the clock

Only done 1000km per year.  :faint: EGR problems are usually due to carbon/tar build up. If it is not en electronic failure, the EGR will be ok ( clean).

Sounds like the car needs an Italian style freeway drive  :happydance:.  Try Milan to Naples, then report back  :mrgreen:
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