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Just bought a 2003 Rio with 53000 miles. Noticed that while in Drive at a stop light or sign, it runs rough. It shakes the car. It seems to run fine otherwise.
 

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I noticed that you're from Florida. Does it run rough when you have the AC on? My 02 Rio will run a rough idle when I have the AC on. Otherwise, it's fine.

I'm from the Southwest area and until recently I was running the AC constantly.
Rough idle and all the rattles included until I switched the AC off.

If this isn't the case, you might want to check your plugs and plug wires and go from there.
 

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Have you replaced your plugs, or are you getting condensation water under your engine cover?
 

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Memorial Super Moderator
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Is the idle ok in neutral or park with your foot off the brake? If it is only rough with your foot on the brake you may have a vacuum leak in a line to the brake booster or a leaking booster diaphram. Try it in neutral with your foot on and off the brake if the idle is rough only with you foot on the brake, suspect leaking brake booster hoses or booster diaphram. You can check the booster by putting your foot hard on the brake and then starting the engine if ok the pedal will sink towards the floor when the engine starts as the booster gets vacuum from the inlet manifold. Best of luck. :cool:
 

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This car sat for awhile. We got an oil, oil filter, and air filter change. Seems to have helped. I did try the brake booster test. It seems fine. I think I will change the plugs and wires.
 

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Memorial Super Moderator
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If the car has sat for a while some of the vacuum hoses might be cracked, a cracked or loose fitting vacuum hose can cause a rough idle. also check that your idle speed is correct, if it is slow the extra load of sitting in drive might drop it further and cause the rough idle.
 

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Hi all, new here. I just got an 05 Rio and have same issue with idle dropping to about 500 rpm at stops. No difference noted with compressor on/off. Car had regular oil changes from dealer, not sure about mx though. I was just wondering if it is easy to increase the idle rpm, seems to like rpms around 7-800. Thanks, trying to make sure car is ok for son as first car.
 

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I've read a lot about KIAs running poorly around 50k miles that the cause was worn out spark plugs. I think the mind set of replace spark plugs at 100k still lives.

Also ....Very important!... be sure to measure the spark gap and re-gap plugs BEFORE installing them. Check the specs in the owner's manual. They may be gapped for a different engine. I also read that KIAs DON'T like platinum plugs.

Spark plug wires like "hoses" can degrade with time and can leak their high voltage to the engine or body frame causing poor idling.
Dave
 

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Marty, heres all the info you need, registration is free, once there click on shop and pick and choose what you need. http://www.kiatechinfo.com/default.asp

The manual does say to gap the plugs at .039 to .043, however the old spec. was .028 to .032. I have better luck with .030, I realize thats not what the current spec. is but my Rio runs better at that setting and gets an avg. of 38 to 42 MPG, so I'm not going to change.

Another thing I've found is condensation under the engine cover and dripping onto the ignition wires causing cross firing. My fix was simple, ran engine till hot and totally dry, let engine cool off and sprayed wires with silicone spray which seales them. I now do this once a year, so far just as effective as replacing the wires and much less expensive. Tip, do this with engine OFF, you do not want any silicone sucked into the intake as silicone is death to O2 sensors.
 

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its the idle solenoid .
its connected to your throtle body, held by to bolts size ten.
there is a wire connector three wires to be exact .
on bolt on the left has to be taken out by a philips bit.
you have to take the coil pack first to get access to it.
its about 300 bucks plus from the dealer.
this solenoid or valve controls the idle of the car.
if you have the keys to on you can hear this thing buzz then you know you have to change it.
 

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sometimes it can be a worn flex pipe in the exhaust. ive been hearing about this prob alot, even my fiancee has this problem with the ac though. no cracks in vacuum lines and booster is fine. put new plugs in and have a k&n filtes so plenty of air. so basicly on this throw away car things are just going wrong,lol
 
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marty-mar
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