2002 Kia Rio misfire issue on cold starts

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.

9 Replies

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.

Was this

answer

helpful?

Yes

Wednesday, October 8th, 2014 AT 9:02 AM

ELIASP87

MEMBER
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?

SPONSORED LINKS

Was this

answer

helpful?

Yes

Wednesday, October 8th, 2014 AT 9:08 AM

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.

Was this

answer

helpful?

Yes

Wednesday, October 8th, 2014 AT 9:53 AM

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?

Was this

answer

helpful?

Yes

Thursday, October 9th, 2014 AT 5:02 PM

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.