Changed Spark Plugs and Coils and still idling rough and running rough

[Mdunbar08]

I have a 2015 Hyundai Genesis Sedan 3.8L and I’m at 107,000 and I new and felt it was time to change the spark plugs...so it was running perfect just felt a light miss so it was time for a tune up...after I changed those spark plugs it’s been HELL ever since...it’s been idling and driving rough since the day I changed all of it...took it to the dealership and it read misfiring in cylinder 2&4 so they told me it was the wrong spark plugs so I buy spark plugs from them and it still does the same thing...I’m a car guy now they are trying to tell me it’s the fuel injectors which I know if it were them it would’ve been acting crazy before I changed the original spark plugs...I’m thinking it’s the wiring harness connected to the whole thing...but idk...has anyone come across this in there Genesis and if so what was the fix.

 

[Andyj]

Subscribed. My 2015 3.8 runs flawless at 51K miles but I expect to have to deal with plugs around 100k. I hope you find rhe plug issue before you replace everything else.

 

[Zay B]

I have a 2015 Hyundai Genesis Sedan 3.8L and I’m at 107,000 and I new and felt it was time to change the spark plugs...so it was running perfect just felt a light miss so it was time for a tune up...after I changed those spark plugs it’s been HELL ever since...it’s been idling and driving rough since the day I changed all of it...took it to the dealership and it read misfiring in cylinder 2&4 so they told me it was the wrong spark plugs so I buy spark plugs from them and it still does the same thing...I’m a car guy now they are trying to tell me it’s the fuel injectors which I know if it were them it would’ve been acting crazy before I changed the original spark plugs...I’m thinking it’s the wiring harness connected to the whole thing...but idk...has anyone come across this in there Genesis and if so what was the fix.

Considering you have a gdi engine with 100k miles Check for carbon buildup with a boroscope if its thick then you may have found your problem and a cleaning may solve it you could also be a vacumr line or inproper instalation of spark plugs however I'm just a guy on the internet may have to bite the bullet and ask a shop