Author Topic: Jerky acceleration  (Read 386 times)

0 Members and 1 Guest are viewing this topic.

  • *
  • Posts: 2
  • 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

  • *
  • Laughter is the best medicine. .
  • Posts: 63,205
  • au Australia
    Devonport Tasmania
  • Best Car Forum on the Net
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.
  • MY18 PD SR & 2014 1.6 GDi Tourer (Prev had 2008  i30 CRDi & MY11 Petrol CW)

  • *
  • Posts: 463
  • fi Finland
    Helsinki
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.
  • i30 cw 1.6crdi -08

  • *
  • Posts: 3,108
  • au Australia
    Samford Valley
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 » »
  • Every FD model; BMW Z3 M; Mitzi Magna(mobile office)

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.







  • 2011 Hyundai i30 crdi 90 blue drive

  • *
  • Laughter is the best medicine. .
  • Posts: 63,205
  • au Australia
    Devonport Tasmania
  • Best Car Forum on the Net
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
  • MY18 PD SR & 2014 1.6 GDi Tourer (Prev had 2008  i30 CRDi & MY11 Petrol CW)

  • *
  • Posts: 3,108
  • au Australia
    Samford Valley
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 » »
  • Every FD model; BMW Z3 M; Mitzi Magna(mobile office)

  • *
  • Posts: 3,532
  • au Australia
    Ipswich
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
  • 2008 i30 SLX CRDi Auto, 2010 i30CW SLX CRDi Auto. 2008 i30 CRDi SX manual, Welly

  • *
  • Posts: 3,108
  • au Australia
    Samford Valley
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.
  • Every FD model; BMW Z3 M; Mitzi Magna(mobile office)