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2021 KIA Forte EX
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Discussion Starter · #1 ·
2012 KIA Optima 2.4L (EX)

I noticed there's a metallic sound from the engine (like a buzzing sound) when applying light pressure to the gas pedal to accelerate, it's really only noticeable at speeds below 50MPH. When I let off the gas pedal, the noise immediately goes away. I have eco on at all times. The engine (2.4L) is original and has about 124,000 miles. The noise started in the last 3 months or so. The car has no error codes stored in the computer or illuminated warning lights on the dashboard. The car is getting slightly lower than average MPG for the winter, but it's not terrible (~30 MPG, mostly highway). I typically hear the noise when driving around parking lots, when I'm traveling at 25MPH or lower. It only happens when driving forward. I don't press down hard on the gas pedal and typically use light acceleration when possible to get up to speed unless someone is behind me or I'm merging into traffic.

I had one shop look at the issue today (not a dealership) and they noted that the exhaust shields are all tight and that the noise is likely from noisy GDI fuel injectors. Two technicians listened to the noise and came to that conclusion. They believe the noise is normal and suggested changing fuel brand and/or trying BG Ethanol Fuel System Defender, which is a 2 part cleaning system which removes allegedly deposits and water. I typically run Techron every other oil change and I usually buy my gas from a Shell (top tier) gas station down the street from the shop. The owner of the shop said they've had many cars towed into the shop after buying water-laced fuel from this particular Shell gas station.

What do folks think of this noisy injectors diagnosis? Assuming the issue is related noisy injectors, any thoughts to make them quieter?
 

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If it's the same noise I'm getting, I'm calling BS. I have a metallic sound under the car even when I'm not driving and the engine fires up to run the AC while sitting parked. (I have a hybrid so it will sit, quiet as a mouse till it needs to cool the interior or charge the battery.) EDIT - I've had the noise since I got the car, so it's not something that's developed over time. - EDIT

I just had it into the dealership, and instead of calling me to get more details for clarification, the tech deemed it as the VESS (Virtual Engine Sound System) which is only on the hybrids so they make noise when driving on electric so as to alert nearby pedestrians there's a car nearby.) I had explained to the advisor at check-in that the noise happens under a load, driving slow and engine running, and even when sitting and idling. Clearly this didn't get relayed properly to the "Master Tech" who looked this over. So their lack of communication leads to wasted time for me having to take the vehicle back, and the tech having to chase down the noise. Plus it doesn't help when the tech takes it out on a flat area and drives it for less than 2 miles to chase a noise. I get that they're busy and trying to keep up with the repair volume, but guess what, you diagnose things properly you don't get returns and pissed off customers.

I know it's a vibrating heat shield based on the sound and previous experience, but the car is under warranty and I refuse to fix things like this myself until the warranty expires. This way they can't say I messed something up and void some form of my warranty.
My father-in-law has a 2012 Optima, and he has the exact same noise and doesn't always happen just like my '15. So needless to say, this is a Kia issue and not us going crazy. Luckily for my F-I-L, he can't hear those kinds of noises anymore. LOL
 

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2021 KIA Forte EX
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370 Posts
Discussion Starter · #3 ·
I decided not to pursue the noise issue further. I ended up getting a loaner while my car was being serviced at the dealership for some suspension work; the loaner was a 2014 KIA Optima LX with 70K and it made the same noise under load, so it's conceivable that it was noisy injectors in my case.

Regarding the dealership experience, I've had similar problems. Several years ago, my local mechanic noticed my radiator side tank was cracked and leaking coolant while he was doing an oil change. The radiator was still under warranty so I visited my local dealership to have it replaced. I was told that the condition was normal and did not warrant pressure testing (even after I pointed out the coolant residue all over the side tank and splash shield). The following day, I went to another dealership who replaced it under warranty without any hassle.

I recently went to my local dealership for an oil change (I was unable to do my usual DIY due to the COVID shutdown). They found $600 in repairs (which I admit, were technically needed but I was avoiding the repairs). When I got the car back from the oil change, I noticed they had chucked the oil drain plug cover. I called them and the manager apologized for throwing out cover and asked me to come back so they could install another one (presumably sourced from another customer's vehicle, as the replacement I received was not new). They also offered a 15% discount on the repairs, so I went forward with the repairs (I was trying to support them as their business had been cut by 2/3 due to COVID). I was working in the engine bay recently and realized that they overtightened the screw holding down the air intake and cracked the plastic. Despite all the chances I give them, I'm continually disappointed with their work. I started to going to local mechanics and I avoid the dealership unless it's warranty related.

I had another experience where the tech accidentally applied black undercoating spray all over my wheels and rocker panels. They refused to clean it as they were too busy (presumably ruining other cars). I then told them I would have a detailer remove the over spray at their expense; suddenly a manager became involved and they cleaned most of it.

I could go on, but you get the point. You're not alone with your experience.
 
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