3.3TT Cold idle slightly rough

[GT2inSeattle]

Hey there everyone.. I wanted to get your thoughts on this. When I go to start my GT2 from cold (say, first thing in the morning or after it's been sitting idle until completely cool) I've noticed that the idle isn't totally smooth.. The sound is almost like a subtle 'miss' where I can hear that the engine didn't completely combust fuel when it should have. My only comparison is that I *never* heard that on my 2.0T 2012 Optima SX. Granted this is a new engine from KIA. But I wanted to compare other experiences from Stinger 3.3TT owners. Once the car is warmed up (even for a minute) it's smooth as silk. Just during that initial warmup I noticed that sound. If needed I can try to record it for people to hear.

Is this normal for the 3.3TT on warmup?

Thanks in advance.

 

[Shockington]

Mine does the same thing. Over 1500 RPM starts and it sounds a little rough. Give it 30 seconds and it smooths out.

 

[Dennis]

Have that too! Makes it different from run of the mill cars where it is always consistent. Makes it Special like a high strung car lol..... nothing to worry about it runs fine when warm! Most high performance cars does that and runs well when warm. Its like missing a heart bit once in a few seconds during warm up. Notice after a 30mins drive the engine is extremely smooth and much quieter.

 

[MerlintheMad]

I remember when we were junior high (middle) school kids. My best friend went to Las Vegas to the Can Am race there. He got recordings of a bunch of cars in the pits idling and revving. The Ferrari was idling very unsmoothly, and I thought it didn't sound very good at all. While they were working on it, they'd periodically rev the engine, I guess to clear it out a bit. Then it would sound like a snarling beast. And it would idle better for a little while then start to run rough again, until they revved it several times.

 

[robz32]

Mine does the same, sounds like it sputtering or miss fire. I guess its due to the rich mixture set on the ECU to warm up the engine. It goes away after a few seconds though.

 

[STINGER]

Completely normal, gets slightly worse if you have colder plugs with a tighter gap as well.

 

[Mr Skillet]

Very normal cold start cycle, many modern cars do this mainly to warm up critical engine and emissions components. Timing adjusted to increase exhaust gas temps. AFR is also on the rich side, excess fuel being combusted in exhaust street also contributed to the louder and different sounding exhaust note during a cold start. Bmw and Porsche cold starts sounds like the engine ingested gravel and is systematically chewing it up angrilly, it's great.

 

[GT2inSeattle]

Thanks guys.. I sorta thought that was the case, but it never hurts to ask. There's no doubt she runs great.. when I pull out and get on the road and flip the switch to "Sport" all the power in the world is right there. Best. Ride. Ever.

 

[Fractyl]

After looking through the forums, it might not be an issue... But I still get some sputtering and slightly unusual idle vibration during stops even after warming up (hours of driving). I don't recall having this level of vibration until after I had to bring it in at 3,000 miles for a really rough/violent idle that triggered the check engine light. They ended up changing the ECU and spark plugs, but the dealership mechanic mentioned that it may also be a fuel line issue (they had to contact Kia Corporate Engineers for a solution, who disagreed). It is no longer triggering a check engine light or as violent, but it's still somewhat there.

Anyone have thoughts on this? Fuel line issue? Engine mount loose? I don't have much car mechanical knowledge, still learning. The consistent vibration/sputtering is felt directly underneath the front seat, and quite noticeable when you stick your hand in between the center console and seat. It's almost as if the drive shaft is shaking loose.

 

[MerlintheMad]

After looking through the forums, it might not be an issue... But I still get some sputtering and slightly unusual idle vibration during stops even after warming up (hours of driving). I don't recall having this level of vibration until after I had to bring it in at 3,000 miles for a really rough/violent idle that triggered the check engine light. They ended up changing the ECU and spark plugs, but the dealership mechanic mentioned that it may also be a fuel line issue (they had to contact Kia Corporate Engineers for a solution, who disagreed). It is no longer triggering a check engine light or as violent, but it's still somewhat there.

Anyone have thoughts on this? Fuel line issue? Engine mount loose? I don't have much car mechanical knowledge, still learning. The consistent vibration/sputtering is felt directly underneath the front seat, and quite noticeable when you stick your hand in between the center console and seat. It's almost as if the drive shaft is shaking loose.

I'm sorry to hear this. It sounds really worrisome. I'd be the squeaky wheel if that was happening to my car. Take the service people for a ride. Ask to ride with them in another Stinger for comparison, etc.

 

[Kazz]

I've heard of spark plug issues causing coil issues and vice-versa. I'd definitely tell my tech about it!