Discussion:
Backfire on startup

Hyundai engine backfires on start up then runs fine after, replaced plugs, mixer diaphragm, rebuilt lp converter with the correct kit. Compression test shows all cylinders good and equal. Truck has check engine light on but can't access codes. Dealer is long distance away. Can you access codes without Hooking dealer only software to system?
Can you get the codes to flash the check engine light?
Any help will be appreciated.
  • Posted 4 Apr 2021 11:54
  • By NHLIFT
  • joined 27 Aug'18 - 16 messages
  • New Hampshire, United States
Showing items 1 - 15 of 15 results.
There is an ECM update that corrects this.
They Backfire and tear the Mixer diaphragm, once you replace the diaphragm and have the dealer do the update you should be good. The dealer can look this up on the Hyundai portal, there is a TSB for it.
Good Luck
  • Posted 15 Apr 2022 02:34
  • By GreatWest
  • joined 15 Apr'22 - 1 message
  • Manitoba, Canada
Ok thanks
  • Posted 4 Jun 2021 21:51
  • By NHLIFT
  • joined 27 Aug'18 - 16 messages
  • New Hampshire, United States
You must post email in profiles
They remove it here
  • Posted 4 Jun 2021 13:53
  • By Bluenose
  • joined 2 Apr'14 - 31 messages
  • Nova Scotia, Canada
Take me as i come, cause i can't stay long....
[email address removed]
  • Posted 4 Jun 2021 11:45
  • By NHLIFT
  • joined 27 Aug'18 - 16 messages
  • New Hampshire, United States
Send your email
It put in profile
I have TSB with part #s
  • Posted 4 Jun 2021 11:22
  • By Bluenose
  • joined 2 Apr'14 - 31 messages
  • Nova Scotia, Canada
Take me as i come, cause i can't stay long....
I will have to take plug apart to try to repair
I will let you know if this fixes my issue
Thanks for the input
  • Posted 4 Jun 2021 10:49
  • By NHLIFT
  • joined 27 Aug'18 - 16 messages
  • New Hampshire, United States
I just repaired wires for now
Plug looks ok
This is common on so many makes
Getting Unicarrier's blowing ECM fuses as O2 sensor heater shorts in harness
So, now we know !
Mixer took a hit from backfires

I didn't re gap plugs to 25 thou, some found this fixed issue
Just glad it's fixed !!!
  • Posted 4 Jun 2021 10:17
  • By Bluenose
  • joined 2 Apr'14 - 31 messages
  • Nova Scotia, Canada
Take me as i come, cause i can't stay long....
Just looked at mine. Found pink wire at cam sensor broken inside of plug. Did you replace plug or splice wires??
  • Posted 4 Jun 2021 06:43
  • By NHLIFT
  • joined 27 Aug'18 - 16 messages
  • New Hampshire, United States
Just fixed Mine
TSB from Hyundai
Cam sensor wire at plug was like elastic
Held on by a few strands
It's easy to get at, right front of motor on top side
  • Posted 4 Jun 2021 05:39
  • By Bluenose
  • joined 2 Apr'14 - 31 messages
  • Nova Scotia, Canada
Take me as i come, cause i can't stay long....
Did you replace mixer diaphragm with a OEM part?
Also vaporizer kits in the aftermarket might look the same but are not. Have to order kits by using the numbers on the vaporizer and mixer.
I also replaced cam sensor but not crank sensor.
Recheck dash to see if you have any codes showing
  • Posted 3 Jun 2021 22:48
  • By NHLIFT
  • joined 27 Aug'18 - 16 messages
  • New Hampshire, United States
Yeah, customer is not happy, but everything is shot from sludge, backfiring. He never replaced the plugs and they were shot, seized. Customer thinks he doesnt have to pay for any parts that didnt fix it!
I've contacted 4 Hyundai techs, they never saw this issue.
Might end up being the injector as it can start if accell pressed half way
Andrew from UK mentioned plug at crank sensor can break wires
that makes the most sense as it's a start up issue. I thought of this first. Asking for help, was told plugs, mixer and vaporizer needed replacement
  • Posted 3 Jun 2021 21:17
  • Modified 3 Jun 2021 21:40 by poster
  • By Bluenose
  • joined 2 Apr'14 - 31 messages
  • Nova Scotia, Canada
Take me as i come, cause i can't stay long....
Problem has not been resolved yet. Need to access codes before continuing as parts are expensive to just throw at it. I will continue to update as I go along. Any input will be appreciated.
  • Posted 3 Jun 2021 21:07
  • By NHLIFT
  • joined 27 Aug'18 - 16 messages
  • New Hampshire, United States
Did you resolve this?
I have exact same issue. Put in the same parts. New Plugs >>>old ones seized in heads as they stick out past head and carbon up or burn. Do this cold!
My vaporiser was choked with oil, diaphram was sutck in bore, But new parts just **** it off, and it's worse. I have not check engine light on, and you need scanner to access codes.
i'm hoping you can let me know if you fixed this before i toss any more parts!!
  • Posted 3 Jun 2021 20:51
  • By Bluenose
  • joined 2 Apr'14 - 31 messages
  • Nova Scotia, Canada
Take me as i come, cause i can't stay long....
Thank you. I will recheck the gap
  • Posted 6 Apr 2021 06:16
  • By NHLIFT
  • joined 27 Aug'18 - 16 messages
  • New Hampshire, United States
Check the plug gap, I think they should be 30 thou, make them 25. If the eml is on chances are its the fuel injector. They are renown going. You cannot access codes without the software I dont think. But backfires are usually down to plug gap.
  • Posted 6 Apr 2021 03:42
  • By andrew_k
  • joined 17 Mar'07 - 325 messages
  • England, United Kingdom

Post your Reply

Forkliftaction accepts no responsibility for forum content and requires forum participants to adhere to our rules of conduct. Click here for more information.

If you are having trouble using the Discussion Forums, please contact us for help.

UN Forklift FD25T-C2JM1
HANGZHOU, Zhejiang, China
New - Sale
Toyota 8FDU30
Flesherton, Ontario, Canada
Used - Sale
Latest job alerts …
Uxbridge, Canada
Daleville, IN, United States
St. Louis, MO, United States
Evansville, IN, United States
Upcoming in the editorial calendar
WIRELESS CHARGING
Aug 2025
MANAGING MIXED FLEETS
Oct 2025
Toplift Ferrari TFC36-48
Stoney Creek, Ontario, Canada
Used - Sale
USD1
SMV (Konecranes) 4531CC5
Balling, Denmark
Used - Sale
Fact of the week
Sourdough bread contains Lactobacillus reuteri, a probiotic bacteria. During pregnancy and breastfeeding, these bacteria can travel from the mother's colon to her breast tissue and be passed to the infant through breast milk. It offers various health benefits, including potential protection against breast cancer.
US confidence index rises sharply Washington, DC, United States
Upcoming industry events …
July 9-10, 2025 - Birmingham, United Kingdom
October 21-23, 2025 - Panama City, Panama