2002 Kia Rio misfire issue on cold starts

Tiny
ELIASP87
  • MEMBER
  • 2002 KIA RIO
  • 1.5L
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 89,000 MILES
One day check engine light came on and got the p0303 ccode ok bought new wires plugs and ignition coil. Replaced it and same thing still. Had some people check it out for me and couldnt firgure it out.I tried swaping plugs and also swaping the injectors and same thing misfire on number 3. Its happens on them morning cold starts then it will run fine afterwards it warms up. Had another place check it and they said it has compression spark and the igectors are working fine because they checkd it with a noid light. But when they sprayed down the wires on the part its connected to the ignition coil you could see sparks and the engine stalling like crazy. So he told me to replace the wires and coil so I purchased it straight from the kia dealer and replaced it and it still misfires. Says number 3 misfire p0303. Im out of answers dont know what to do next please help.
Wednesday, October 8th, 2014 AT 7:14 AM

9 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
One thought, you could have a vacuum leak in the intake system. The leak could seal after the engine warms up? Just a thought.
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Wednesday, October 8th, 2014 AT 9:02 AM
Tiny
ELIASP87
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  • 6 POSTS
Hmm but why only on cylinder 3 only wouldnt it be misfiring on all cylinders? What test could I perform to see where the leak is or do I just replace the intake manifold gasket?
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Wednesday, October 8th, 2014 AT 9:08 AM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
With intermittent issues, you have to test when problem is ongoing. Test when engine is cold, if you haven't.

On cold engine, you could do cylinder compression test on all cylinders, see how # 3 reading relates to other cylinders?

You could spray carb cleaner around intake gasket to see if it effects idle? Anytime you use a flammable spray, there are safety issues. Safety is YOUR responsibility. Keep a fire-extinguisher handy, just incase something unexpected happens.

It very well could be other issue, but, I can't see anything from here.
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Wednesday, October 8th, 2014 AT 9:53 AM
Tiny
ELIASP87
  • MEMBER
  • 6 POSTS
Ok well I had the car checked out again and said it may be a exhaust valve they have to run some test to check the valve also check the timing to see if its that. But if it was the valve wouldnt it be misfiring all the time?
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Thursday, October 9th, 2014 AT 5:02 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
You asked a good question, that I can't answer. It sounds like they are not sure, so they have to take a look.

A reputable shop that can look at your vehicle should be able to tell you more than I can over the internet. All I can do is list possibilities.
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Friday, October 10th, 2014 AT 9:18 AM
Tiny
ELIASP87
  • MEMBER
  • 6 POSTS
Ok well can sticky lifters can cause a misfire on that cylinder 3?
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Wednesday, October 22nd, 2014 AT 12:43 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Usually dohc engines don't have the type of lifters that I'm used to seeing? I'd have to look at the vehicle.
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Wednesday, October 22nd, 2014 AT 2:57 PM
Tiny
ELIASP87
  • MEMBER
  • 6 POSTS
These lifters are not self adjustable there a round metal tappet that sit between the cam and valve when the cam lobe hits the lifter its suppose to open and close the valve and since it gets stuck I wonder if thats causing my misfire on cold starts
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Wednesday, October 22nd, 2014 AT 3:59 PM
Tiny
JDL
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I suppose it is possible.
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Thursday, October 23rd, 2014 AT 12:00 PM

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