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2001 Kia Rio
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Discussion Starter · #1 ·
Hello,

My son has very good luck with forums such as this for his own car, and currently I am at a loss on where to go with my own. I have a 2001 Kia Rio that has decided to suddenly take a serious turn for the worse.
I experience very rough idle after about a minute of the car running as well as absolutely awful acceleration. At times it seems to be running on about 3 cylinders, which is not a good feeling. I do not NOTICE a knock, but my error codes seems to disagree. I am receiving quite a few error codes, and was hoping you guys had an idea where to start, because currently I am shooting in the dark.

Codes (Autozone, so hopefully the correct format):
p0171--system too lean
p1166-- lambda bank control limit (no idea what that means)
p0302---cylinder 2 misfire
p0304---cylinder 4 misfire
p0300---multiple cylinder misfire (well thanks)
p0325---knock sensor
p0420---catalyst efficiency below threshold

Now, I have replaced my plugs and wires quite recently, and I checked the gap to match the manufacturer specifications. I did read that this gap may be slightly off when you buy plugs from a place like autozone, but I doubt it would cause this rough of an idle. My son very recently had a knock sensor issue, and it fixed a bit of his timing once he replaced it, but I am unsure because pretty much every one of these errors points to a vacuum leak that I have yet to discover.
 

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2002 Kia Rio, 2011 Kia Sorento 2005 f 250 1996 geo metro 1992 f 150
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1,023 Posts
coil pack connector maybe? it's been known to burn up 1 connector supplies cylinder 1-3 and the other does 2-4. also blocked cat just a thought. The dreaded p1166 i had them same codes when my 2nd cat blocked up the car would not even go up a little hill . Reguards Ronjohn
 

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2012 Kia Soul+, Kia Sportage SX FWD
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468 Posts
Could be an air leak. Check all the hoses arounf the throttle body. A bad IACV (idle air control valve) will cause symptoms similar to an air leak.
What happens is if too much air is getting into the system (and NOT being metered by the MAF sensor) the fuel trim gets freaky and you will get 3 or 4 codes that may send you chasing phantoms. If you have over 120k miles you need to look at catalysts possibly being bad. But my Rio had a bad IACV that made me pull my hair out. The dealer didn't even diagnose it right. I say check for any obvious bad hoses, then clean the MAF sensor and the IACV. Also clean the throttle body area to get all the gunk out of the intake and butterfly valve area. Make sure you have a good air filter and no restriction in the intake anywhere. Make sure the connections on all the sensors are good too. TPS, IACV, MAFS, IAT. Alos if the mileage is high you should look at replacing the oxygen sensors, as they have a finite lifespan and do NOT last indefinitely. I'd recommend changing ANY O2 sensor after 120K miles....even if it seems to work fine. Read up on catalysts and O2 sensors and you'll see why I say that.
Good luck.
 
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