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Rough Idle when starting car ..even on 70 deg evenings the night before

6K views 11 replies 6 participants last post by  Touring_tech 
#1 ·
Please advise if anyone else has noticed rough idle in mornings when you start up car ? Sounds like it's missing.. sounds rough under hood and from the exhaust ... after about 5 mins it goes away and idle is back to normal. Please advise if anyone has spoke to dealer regarding this issue or if having the same issue . It did not due this for the first 3500 miles .. but after I had lost power while driving ..pushed on gas and no acceleration... it started ... took to dealer and they just swapped ignition coils...did not replace with new ignition coils.. since they said there was a miss fire code they saw.. please advise thanks ... even after they did that ...still having rough start/idle in mornings... thanks
 
#2 ·
How'd they justify not replacing one or more coils? Normally you do a coil swap to see if the misfire follows the coil. If the misfire persists on the same cylinder then the source of the problem is not the coil. I would think with a warranty repair they wouldn't make you mess around with a coil swap.
I'd get it back to the dealer ASAP. If it's misfiring that typically means some unburnt fuel is getting to the cats, which is damaging to the cats.
 
#3 ·
They didnt replace the ignition coils ..because they swapped them and they advised me that they fixed it by swapping them .. but that is a concern that they just did a bandage to the issue and didnt fix it correctly ... would that be an issue for you too .. if they had done that as a fix for a new car ?? Thanks And when you stated Cats in your response.. you ment the catalytic converter ? Yes ?
 
#5 ·
I'm at Hyundai Dealer ..the tech started it up .. & it was rough sounding .. & rpms at 1500 rpm .. then about 2 mins later it dropped to 900 rpms and ..not rough / throaty sounding ... very smooth sounding .. he acted as it was supposed to do that ..when prior to the misfire .. and acceleration / power ..lack off at 3593 miles .. it was not sounding that way ... I will wait & see what they find out ...

also the issue with my tires wearing on inside edge (cupped) on rear of car ... serv advisor stated it was due to rotation .. I know its usually caused by suspension issues/ shocks .. or out of balance tires .. please advise
 
#12 ·
I'm at Hyundai Dealer ..the tech started it up .. & it was rough sounding .. & rpms at 1500 rpm .. then about 2 mins later it dropped to 900 rpms and ..not rough / throaty sounding ... very smooth sounding .. he acted as it was supposed to do that ..when prior to the misfire .. and acceleration / power ..lack off at 3593 miles .. it was not sounding that way ... I will wait & see what they find out ...

also the issue with my tires wearing on inside edge (cupped) on rear of car ... serv advisor stated it was due to rotation .. I know its usually caused by suspension issues/ shocks .. or out of balance tires .. please advise
On the tire wear issue. I’ve been fighting this since day 1. The factory alignment has a bit of camber in the back but a shit tonne of toe IN. That’s what’s causing the cupping. Just have it aligned by a good alignment shop. Mine was so bad and noisy because of the tires scrubbing that I thought I had a bad wheel bearing.
Basically Hyundai dealers don’t fox anything unless it’s on fire in their shop, or there’s a permanent code. I had a misfire and drove it to the shop, with it running on 3 cylinders, showed the advisor, and the car never threw a code. They shut it off, started it again, it ran fine, so they said it was a “glitch” and to come back if it thew a code. FUCK HYUNDAI WARRANTY. They’re throw away cars.
 
#11 ·
I have a 2020 Elantra gt n line
rough idle when starting took it to dealer said it was normal
car started spuddering and was misfiring took to dealer
replaced coil
back to same problem
anyone figured this out yet
Rough start in mornings or when has been sitting for several hours, dealership says its normal
Regarding misfires, after 3 dealerships and multiple visits and the run around (dealership says cant do any repair without codes on hyundai scan tool) even though I showed them codes that came up from my reader & advance auto scan . FINALLY ..got a dealership that acknowledged that there is ignition coil issues!
They only got code for a different coil..but they agreed after I showed them the numerous visits to other Hyundai Dealerships..that it is an issue. So after about 40k miles on my 2019 Hyundai Elantra GT N Line, they replaced ALL 4 Coils & All 4 spark plugs .. so far 10k latter runs much better & no misfires. Still Rough start for about 1 minutes on start up. But much better regarding misfire issues!
 
#9 ·
I've never gotten around it. My dealer basically refuses to do anything without an error code. I've replaced all my coils myself, checked plug gaps, etc. It's always a rough start unless it really warm out. I also have been dealing with a no code miss since day 1.
 
#10 ·
This has something to do with the emissions valving. When you start an engine, it redirects exhaust gas into it for a little while, basically the time periods being described in this thread, and then normal operation commences. EGR valve or EGR are common terms for it. The descriptions given match the operation IMO.
 
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