Well, if is only happening when it is damp, I would vote for the new wires and plugs. They tend to arc over or drop voltage through leakage when old and damp. Happened to several vehicles of mine. That 100,000 miles between tune-ups is BS!
About a week ago I started the KIA (rainy and in the 40s) and it was running rough under acceleration. It never stalled though. I filled it up and put some STP fuel injector cleaner in it. Upon leaving the pumps it was running better in a matter of minutes. And no I don't believe it was the STP. I took it in for an oil change and during their PM they didn't see anything irregular. How well they check I don't know. You would think these days they would throw ever car that came in on the diagnostic machine for free and make money on the parts and labor they would sell. Anyways, today, about 5 days later and at a 1/4 a tank it starts acting up again. Same weather. I am going to go fill it up and see if that fixes it. The only thing that might tell me (This is my theory) is that the fuel pump might be weak or filter clogged and needs more Gravity/pressure to work. I'll run some more STP thru it.
It has about 65,00 miles on it. So I think I'll start with Plugs and wires. Is NGK the recommended ones here in the group. Is there a good online parts store to order from?
Thanks, Phil
==== Try this injector cleaner first it's much better then the STP stuff.
I agree with your faulty fuel pump theory.
-- Christian
Don't overlook a loose gas cap , you left the pumps and it started running better within minutes . My Rio and several other manufacturers run badly with a loose gas cap .
The other Phil
I have a KIA also and heres what i experienced. At about 70k miles my ignition coils and cables started acting up. It did the exact same thing run rough then once it got warmed up no problems. I took out the presumed ignition coil and tested it and it was defunct plus i found out kia has redesigned almost all there parts like 2 or three times. Before you do that though just change your spark plugs. If no improvement then try your coils.
Thanks. I'll wait for warmer weather and start working back from the plugs to the coil.
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