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2002 Kia Rio Cinco
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Discussion Starter · #1 ·
I have a 2002 kia rio cinco 1.5L engine, (97,000 miles) i have changed the timing belt and water pump 2 weeks ago, changed the spark plugs, spark plug wires, i have checked the compression in each of the cylinders and they were all equal (175 psi). However my check engine light is on and reads P0304 which states that cylinder 4 misfires. I have noticed by accident that there is a crack in the exhaust manifold right under where cylinder 4 is, and air gets out from it. Would it be the exhaust manifold that causes this or something else?? Thanks, appreciate the help.
 

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2012 Kia Soul+, Kia Sportage SX FWD
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That may be a problem but an exhaust leak won't necessarily cause misfires. Did you gap the plugs correctly? and What plug did you use? The plugs usually come pre-gapped too high, so you need to make it smaller. .028-.032" seems to work best. Plain ol NGK stockers just seem to fire best.....all the fancy plugs are a waste of money.
 

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2002 Kia Rio Cinco
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Discussion Starter · #3 ·
They are just the most common spark plugs however I do not think they are the problem because the Kia rio came gapped at 0.044 from stock, I already ordered a new exhaust manifold and I'll see if the crack was the case, but thanks for the help man I appreciate it
 

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Discussion Starter · #4 ·
Okay so I changed the manifold, changed the coil, and the rough idle stopped, the car runs like new, however I am still getting the check engine light on and the OBD still reads that cylinder 4 is still misfiring...I checked the compression in each of the cylinders and they are all equally good...Anyone know why this is still happening? Do I need to drive the car around for a bit until the check engine light goes off? Thanks
 

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Ford Escort '01, Kia RIO '03
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Gap the plugs to .028 to .032. That is per specs for your car.

BTW, what is "the most common plug"? Suggest you use OEM plugs, this is what KIA'S like.

To clear CEL disconnect battery for 15/30 minutes and reconnect.
 

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2008 SpectraSX, 2014 Optima LX,2006 Jeep Liberty, Linux Mint Mate
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jcwit is correct...you have the gap way too large and this can cause mis-fires on all 4 cylinders.
The pre-gapped plugs are wrong and MUST be re-gapped to .028"~.032"
Most KIAs came with NGK plugs and they have been proven to be the least troublesome plugs.. KIAs don't like fancy design/multiple element/round grounding element plugs...NGKs don't create firing errors.
Dave
 

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2012 Kia Soul+, Kia Sportage SX FWD
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Hey Evilbob, I had a 2004 and started having trouble after changing my timing belt too. I changed my coils/wires/plugs/injectors, and kept getting weird codes and misfires. I found/fixed 2 problems that ended my misfires. First, my cams were one notch off. I could not get the marks to sit straight up as the book shows, when I was installing timing belt, so I left one slightly right while one was up on mark. Ended up having to move them so they sat slightly pigeon toed( trust me that is where they sit based on cam lobe positioning). Second and probably the most critical fix was replacing my first catalyst. It was clogged, and the codes it caused were freaking me out! The last thing I did before I sold the car was replace the IAC valve. Car ran fine after that, but wife still made me sell it.... (it had 147,000 miles on it).
 

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2002 Kia Rio Cinco
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Discussion Starter · #8 ·
Ahh I see... I will change the gaps and see if it still shows up, I really appreciate the help. Thanks a bunch!
 

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2002 Kia Rio Cinco
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Discussion Starter · #9 · (Edited)
Ok so it turns out that I had already gapped the spark plugs from .044 to 0.032, so it's not the spark plugs. And like I said only cylinder 4 is misfiring according to the OBD...However the car runs like brand new, no more rough idling or any of that nature. The timing belt, and the other 2 belts have been changed as well with the O2 censor, the coil, iac valve, the exhaust manifold...the compression in each of the cylinders are all equal and good, which is why it's confusing as to the check engine light still comes up and the OBD still reads the same exact error message...any other suggestions would be great...thanks appreciate it!
 

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OK...I'm coming in a little late.... but I see one item missing...
You say you replaced the coil... was there only one coil and a distributor
or are there two coils? Have you tried switching the coils..the mis-fire may follow the coil. The one that was bad was probably made the same time as the second one and it may only be on it's way out and only slightly flaky.
Just a thought..
Dave
 

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2002 Kia Rio, 2011 Kia Sorento 2005 f 250 1996 geo metro 1992 f 150
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Did you clear the code and get rid of it after you fixed it, there may be a pending code try getting rid of the pending code for what it is worth Reguards Ronjohn
 

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If you are sure its not a plug...wire...or coil, just swap the #1 and #4 injectors and see if problem moves to PO301... Just a thought ...it may be a bad injector. Or an intake leak on 4...
 

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2002 Kia Rio Cinco
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Discussion Starter · #13 · (Edited)
The car doesn't have a distributor it has a crank position sensor that works with the ICU. It has one coil but 2 parts that 2 cylinders go in each part, I don't know if that makes sense...Anyways, as for the injectors, I tried the above and i still get the P0304 error code. There's no intake leak either. I tried clearing the code and the check engine light came back on. It's very strange because the car is running really great compared to when I first got it. The rough idle stopped, acceleration is a lot smoother, etc.
 

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2002 Kia Rio Cinco
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Discussion Starter · #15 · (Edited)
Okay so it turns out that the spark plug wires I bought brand new weren't working properly. Last night the car was running good and today when I tried to turn it on the car wouldn't start. I wanted to check the compression in each of the cylinders. So everything was running, the engine, the timing belt, etc, and I had no compression in every cylinder. Weird right? Would it be the starter that caused this? anyways I put in the old spark plug wires and put the spark plugs back in and the car started all of a sudden and ran better than it did ever before. I cannot explain why this happened, because the timing belt is brand new...So I was wondering why I didn't have compression the first time.

EDIT:
I changed the fuel pump today and the car is working, and working pretty good, not fantastic, but good. However, I still get the same error with my OBDII, P0304...I tried clearing the code and I'll see if it pops up again but I can't get it smogged with the check engine light on. Any other ideas? Thanks, and appreciated.
 
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