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1999 Kia Sephia LS
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13 Posts
Discussion Starter #1
Ok, here's the problems I'm having. When I'm driving uphill, which I have to everyday for work, the car loses power. One side of the hill is much steeper, but shorter. I can usually go about 45-50 on this side. The other side is very gradual and long. I can on a good day go 35-40.

Another problem is it jerks back and forth on occasion. It's been doing this a lot less, but still does it. It seems like the longer I run it, like if I go somewhere and leave it running, when I get back in it does it more often. It feels weird when it does it too, like if you gave it a bunch of gas and suddenly let off, then gave it gas again real quick and let it off.

I had the check engine light checked at Autozone and got a MAF sensor error. It wasn't even hooked up. I bought a brand new MAF and hooked it up and the car would start and run for a second, maybe two, then die. The people that owned it before us I think tried to make a racecar out of it. It has an aftermarket cool air intake kit on it. But I did notice there was at least one part missing though.

Another code I got was bad O2 sensor, but the guy said that the MAF could actually be throwing the O2 sensor off.

I have replaced the fuel filter, the spark plugs, the MAF, all to no avail. ANY help is greatly appreciated!
 

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Premium Member
2015 Buick Verano "Leather Group", 2015 Kia Optima Hybrid
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6,117 Posts
What is the code? PO????
If there is a piece missing on the intake, that does not help anything, it is there for a reason.
Have you made sure the intake does not have any leaks? Tighten all connections to make sure.
 

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2000 Kia Sephia
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103 Posts
Is the intake air temperature sensor missing? When I rigged an intake, I had to relocate the IAT. Stock, it's screwed into a bung on the air filter box.
What happens if you disconnect the battery for a few minutes then reconnect? This would reset the computer.
 

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1999 Kia Sephia LS
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13 Posts
Discussion Starter #4
Yes, everything is tight. No, the sensor is not hooked up. Where did you relocate it to? I'm not sure the one on the air box I bought is good. But that is something new to try in the morning.
 

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2000 Kia Sephia
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103 Posts
I drilled a hole on the pipe that the MAF is attached to. I forgot the diameter, but I had to buy a bit. I used hi-temp silicone to glue in the bung, then screwed in the sensor. You should be able to do something similar. just remember that the wires going to it are short :p
 

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1999 Kia Sephia LS
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13 Posts
Discussion Starter #6
Ok, got a complete kit for the cold air intake. I pieced it together with my new MAF. I pulled the air temp sensor from the air box I bought on eBay and put it in. After getting everything together, I took the positive off for about 45 minutes to reset everything. When I put the positive back on and started the car for the first time, it ran for a few seconds and died. When I started it again, I revved it a bit, but when I'd let off it'd die. I did this repeatedly until it would stay running by itself. The idle was pretty terrible though. I drove it around for a little bit. The first two times I pulled to a stop, it died. It seemed to gain a ton of power though! It's running a lot better, but the gas seems to "stick" at times. Like when I pull to a stop and have the clutch and brake in, it starts to rev like I'm holding the gas, except I'm not. Will this clear up, as part of the "learning process" or did I create a new problem? I hope it's just part of the learning process, because it's running a lot better!
 

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2008 SpectraSX, 2014 Optima LX,2006 Jeep Liberty, Linux Mint Mate
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6,939 Posts
The engne control computer (ECM) does have to "re-learn" how to control the engine when the battery has been disconnected and it's memory is wiped..
It looks like you have had more than one problem. The first was the air temp sensor missing and the second could be the IAC (idle air control) valve in the throttle body and/or the butterfly valve (round disk that opens and closes) sticking.. The IAC valve controls the idle speed of the engine and can stick when carbon or gunk sticks to it's surfaces causing the valve to bind and give irratic "no idle"~"high idle" problems. I see no mention of mileage on the car but with it being a 1999 and with "average"miles per year it is probably over 100k. Look into the throat of the throttle body (aluminum tube that the large rubber hose is attached to. You should see the butterfly valve. The insides should be clean and not dark and stained. If there is buildup of carbon/gunk clean the insides with choke and carb cleaner and a soft cotton rag and an old tooth brush. The IAC is usually mounted on the outside of the throttle body and can be located by the "buzz" it makes when the ignition switch is in the ON position but when the car has not been started...It probably needs cleaning or replacing also...After the clean/replace work disconnect battery to clear it's "bad thoughts/memories" and then reconnect... Give the ECM time to re-learn air/fuel mixture, idle adjustments, transmission shift points, etc...
Then post back to us...
Dave
 
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