Kia Optima Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
So I found this issue by accident. My air conditioning sucks unless I'm driving, but I found if I rev my car for a little bit (doing this while parked) it will start to blow cool air. One time doing this, the rpm dropped to idle while I was holding the accelerator pedal in a constant position. If I pushed the accelerator more, nothing would happen, but if I let off the accelerator completely and then pushed on it again, then the rpm would increase normally again. At first, I thought it may be some overheating protection system and just figured I should stop revving my car to cool it down, so I don't do that anymore. Some time soon after (somewhere between a couple days to a week later), the rpm started to drop to idle while I was driving. This time I'm not at constant rpm most of the time because I live in a city with plenty of stop-and-go unless I'm on the freeway. Obviously something is wrong, but at least it doesn't seem dangerous yet. It works the same way while I'm driving, if I let go of the pedal briefly and then push the pedal again it works normally for a while, but it will do this at least a few times in a normal 10-20 minute drive. I needed to take the car to the dealer anyway for a different issue, so I told them about the rpm issue to see if they could figure it out. When I got the car back, the dealer told me they couldn't replicate the rpm issue. I think the dealer was full of it and probably didn't try because I told them exactly how to replicate the problem and it only takes about 30 seconds or less to make it happen. They told me what I already thought and said it may be some protection system. Driving home from the dealer, not only does my rpm still drop sometimes, but now the ESC (electronice stability control) light illuminates and stays on (no blinking, just constant illumination). I called the dealer to ask what happened and they said they never saw the ESC light, that I could bring it back if I want but there will be another diagnostic charge. The ESC light resets every time I turn the car off so the next time I drive it takes a little bit, but eventually comes back on during the drive. I'm not sure how or if the ESC light is related to the rpm issue. I tried turning the ESC off and the "ESC OFF" light comes on right next to the ESC light, but it doesn't change anything. The rpm still drops every once in a while.

Does anyone know what could cause this or what I should look into first? I'm not super knowledgeable on this stuff so I'm definitely going to take it in somewhere but if I have an idea, then maybe I'll be able to take it to a mechanic better suited for this issue. Or maybe I'll have to take it back to the dealer but at least I can tell them what I think it is so they don't tell me they can't find the problem again.
 

·
Registered
2011 Kia Optima
Joined
·
2,529 Posts
Well, that's a strange one especially when driving. Heard that if at idle the rpm is raised for a period of time the ecu will bring it down, true/false don't know never ran into the problem.

The A/C compressor needs to be replaced, or the electronic control valve at the back of the compressor. When the valve malfunctions you can have ice cold air, but at times it will take miles before it starts cooling and non existent at idle.

It shouldn't matter when driving, but check battery voltage and clean the cables and posts as with these new cars it can create a multitude of problems.
 

·
Registered
Joined
·
4 Posts
So I found this issue by accident. My air conditioning sucks unless I'm driving, but I found if I rev my car for a little bit (doing this while parked) it will start to blow cool air. One time doing this, the rpm dropped to idle while I was holding the accelerator pedal in a constant position. If I pushed the accelerator more, nothing would happen, but if I let off the accelerator completely and then pushed on it again, then the rpm would increase normally again. At first, I thought it may be some overheating protection system and just figured I should stop revving my car to cool it down, so I don't do that anymore. Some time soon after (somewhere between a couple days to a week later), the rpm started to drop to idle while I was driving. This time I'm not at constant rpm most of the time because I live in a city with plenty of stop-and-go unless I'm on the freeway. Obviously something is wrong, but at least it doesn't seem dangerous yet. It works the same way while I'm driving, if I let go of the pedal briefly and then push the pedal again it works normally for a while, but it will do this at least a few times in a normal 10-20 minute drive. I needed to take the car to the dealer anyway for a different issue, so I told them about the rpm issue to see if they could figure it out. When I got the car back, the dealer told me they couldn't replicate the rpm issue. I think the dealer was full of it and probably didn't try because I told them exactly how to replicate the problem and it only takes about 30 seconds or less to make it happen. They told me what I already thought and said it may be some protection system. Driving home from the dealer, not only does my rpm still drop sometimes, but now the ESC (electronice stability control) light illuminates and stays on (no blinking, just constant illumination). I called the dealer to ask what happened and they said they never saw the ESC light, that I could bring it back if I want but there will be another diagnostic charge. The ESC light resets every time I turn the car off so the next time I drive it takes a little bit, but eventually comes back on during the drive. I'm not sure how or if the ESC light is related to the rpm issue. I tried turning the ESC off and the "ESC OFF" light comes on right next to the ESC light, but it doesn't change anything. The rpm still drops every once in a while.

Does anyone know what could cause this or what I should look into first? I'm not super knowledgeable on this stuff so I'm definitely going to take it in somewhere but if I have an idea, then maybe I'll be able to take it to a mechanic better suited for this issue. Or maybe I'll have to take it back to the dealer but at least I can tell them what I think it is so they don't tell me they can't find the problem again.
I'm having this exact issue! I replaced the spark plugs, carbon build up removed, battery replaced etc and still having this issue, no check engine light or code this time. Only the first time had check engine light but no code.

2012 Kia optima ex
 

·
Registered
Joined
·
4 Posts
I'm having this exact issue! I replaced the spark plugs, carbon build up removed etc and still having this issue, no check engine light or code this time. Only the first time had check engine light but no code.
Btw I took it back to the mechanic and they told me to replace the entire engine for$7k wtf
 

·
Registered
Joined
·
4 Posts
Btw I took it back to the mechanic and they told me to replace the entire engine for$7k wtf
This might sound crazy but it's your brake light switch. Either the switch is bad or the rubber grommet that contacts the switch has rotted away. Your car has brake over throttle interference, meaning the ecu always lets the brake win if it's depressed at the same time as the throttle, it's a safety thing. Your car thinks your trying to hit the brakes at the same time as the throttle so it cuts power. After paying a kia dealership to not be able to replicate the problem I fixed it myself 2 weeks ago, it's a $6 part. I had all the same symptoms as you guys
 

·
Registered
2011 Kia Optima
Joined
·
2,529 Posts
Good info and could very well be the problem, but one can drive these cars with brake lights on and there's not a problem. In fact, there was a recall, Hyundai as well as Kia for the problem of the lights remaining on, but no drive-ability problems.
 

·
Registered
Joined
·
4 Posts
That's actually how I found the problem. Got home from the dealership with no diagnosis and went to plug my cheap scanner in, pressed my start button for power to the scanner and the car started without having to depress the brake pedal! Shut my car off, unplugged the scanner and then noticed the brake lights were on. I pulled up on the brake pedal by hand and sure enough the brake lights went out. The brake light switch didn't actually fail, this rubber grommet did.
248660
 

·
Registered
Joined
·
4 Posts
That's actually how I found the problem. Got home from the dealership with no diagnosis and went to plug my cheap scanner in, pressed my start button for power to the scanner and the car started without having to depress the brake pedal! Shut my car off, unplugged the scanner and then noticed the brake lights were on. I pulled up on the brake pedal by hand and sure enough the brake lights went out. The brake light switch didn't actually fail, this rubber grommet did. View attachment 248660
Hey man thanks for finding this and responding so quickly. You are probably right! However, my brake lights aren't on, I'll need to double check when i get time. I found some videos on this and seems like an issue. He also explains loss of power randomly and such. Exactly how you explained it

Just incase this is the issue where can I buy one of these rubber stoppers?

EDIT: This is the part number 328763Q100
 

·
Registered
Joined
·
4 Posts
Unfortunately I don't have a source for the rubber piece, I used something else. I used a plastic bolt that was in my bucket of misc. parts. It matched the old rubber piece for thickness. I didn't want to use a regular metal bolt as that would wear the plastic switch. I ordered a new switch but never installed it once I found the problem. It did not come with a new rubber piece.
248661
 

·
Registered
Joined
·
4 Posts
Unfortunately I don't have a source for the rubber piece, I used something else. I used a plastic bolt that was in my bucket of misc. parts. It matched the old rubber piece for thickness. I didn't want to use a regular metal bolt as that would wear the plastic switch. I ordered a new switch but never installed it once I found the problem. It did not come with a new rubber piece. View attachment 248661
BRO i think you 100% right. Look at mine. THANK you so much, I'm going to fix this and give an update ASAP

248662
248663
 

·
Registered
Joined
·
4 Posts
Yeah, after seeing that pic I'd bet my right arm that's your problem. If you find a source for that rubber piece let us know. My plastic bolt has been just fine, but I don't like recommending hillbilly fixes like that to other people.
 
1 - 11 of 11 Posts
Top