Car starts somewhat roughly, idles horribly for a few seconds, then dies


#1

It’s an 05 Kia Rio. I’ve recently put a bit of work into it due to a few issues which were fuel related, namely replacing the fuel filter/pump. It also has brand new spark plugs. That solved the issue that originally put it on blocks for a few months and it ran fine for the past few weeks.

Today I went outside to drive to work and got the symptoms in the title. I know it’s not a spark issue because it does start, and I used it on accessory to air up my tires this morning.

I’m just not sure where to go next. I’ve done a bit of searching and have found recommendations for checking the grounds and the distributor cap.

A few notes -

  • While running at rough idle, depressing the accelerator makes it die faster, rather than keeping it running.
  • It rained last night and this morning. It’s about 70 outside instead of the 80-90 it’s been the last few weeks.
  • No check engine light, but I’ve only tried to start it about 10 times.

#2

Since you mentioned rain, it’s a common problem that the insulation on old spark plug wires degrades to the point that atmospheric moisture (ie rain) will cause the plug wires to short out and cause the engine to run rough, stall, or not start at all.

First thing I’d do is install new spark plug wires.

If that doesn’t solve the problem, next thing to check would be the idle air control valve (IAC) and mass airflow sensor (MAF). Dirt in/on either of those can also cause your symptoms.


#3
starts somewhat roughly, idles horribly for a few seconds, then dies.

That was the exact complaint my ex-wife had. Not about her car. About me. lol …


Ok, back to your car problem. I’m guessing some kind of fuel problem. Especially b/c the car sit unused for several months. I guessing clogged injectors. Mechanics have tests they can do to prove or disprove this. Fuel pressure drop tests, Injector balance tests, etc.

If I had this problem on my own car, first thing I’d do is what jesmed1 says above, about the spark plug wires. I’d at least inspect them for any signs of cracking insulation.

Then I’d have all the diagnostic codes, stored and pending read out of the engine computer memory.