P300-p304 Missfire in all cyl. And random.

[flashover]

2005 Rio 170k. Car was barely drivable. Sputtering, reving, and stalling. Kia service told me that it needed a short block because the compression was between 120 and 130. I didn't believe that that was causing the problem. I replaced the plugs and wires, same problem. I replaced the coil pack and reset the codes, The car is actually drivable now, about a 90% improvement. But, it still has a slight sputter when accelerating and the Missfire codes came back. It also shutters a bit when at cruise speed on a flat road or downhill. I think I need to look at the rest of the ignition system. Does anyone have a diagram of the whole ignition system and vacuum system. Unless somebody has another suggestion.

[DavesSpectra]

Hi flashover...
Your comment "Sputtering, reving, and stalling" can also be caused by a dirty IAC (idle air control) valve located in the throttle body and visable when the large rubber air hose is removed. Try cleaning it with choke/carburator cleaner...
Also poster ronjohn will tell you to check your catalytic converters for causing back pressure to the engine, misfiring and poor performance.
120~130 PSI is not that bad especially if all cylinders are all in that range. You probably got a bad Dealer service department.
Read up on the 2001~2005 Rio section of this forum...Lots of good info..
Dave

I see from your other posts you checked the cats...have you cleaned the IAC?

[ronjohn]

I don't know about your compression but that's low but you can get on kiatechinfo.com http://www.kiatechinfo.com/ free just have to register for service info. hopefully your timing bellt is ok. use kia tech to help i had the same prob/codes with my 02 rio. did you have a p01166 also, Can you go uphill with good power or just on the level or down hill if so check your cat's also clean your iac valve. Good luck Reguard's Ronjohn

[flashover]

Here is what has been done.
Plugs and wires (plugs were gapped to popular recommendation on this site)
New catalytic converter
Cleaned and tested IAC
timing checked and verified by dealer
Cleaned throttle body
Tested TPS with OHM meter
Removed and vacuumed entire exhaust system
Dealer did a leak down test (tested fine)
Swapped out MAFS with another used one (no change)

All of the above was done and I still couldn't make it up a 5%grade for 20 feet. I wouldn't pull into traffic because I didn't know if I was going to be able to get out of the way. I had pretty much given up on the car and posted it on Craigslist as a vehicle with mechanical issues. But then I started thinking about what the dealer said and I realized, compression doesn't have anything to do with the Misfire.

Today I replaced the coil pack.

Took the car for a drive and I was blown away by how much of an improvement there was. The car was downshifting and accelerating, the sputter was minimal and pretty much only when I am accelerating from a stop. I can climb hills and I even passed a car in the passing lane on a 50mph divided highway. Like I said before the car is actually drivable. But the codes did come back so I even though I almost got it licked, I still have some work to do.
I did not have P01166 , Timing belt was don about 40,000 mi ago. If I get the car running smooth I will probably do it again. I don't want to put a lot of new parts on an engine that is trashed. If it is.

[flashover]

I need a picture and list of parts for the ignition system and the vacuum system from the service manual if anyone has it. I have a feeling that there is either another ignition part that is bad or I have a vacuum leak.
Or could it be the cam or crank position sensors. Since I am getting a misfire could it be that the computer is not being communicating properly with those sensors.

Does anyone have procedure to test the cam and crank position sensor.

[ronjohn]

Flash no way to get on http://www.kiatechinfo.com/ for service material the diagrams and test procedures are there. I have an 02 book it my not be the same as an 05. Did you change the coil pack twice and what cat did you change there are 2 the 2nd cat was blocked on mine. You could get on a dealer web site they list the parts and location. there is also a known issue with the coil pack female connector's going bad. Best of luck. Reguard's Ronjohn

[flashover]

Ok, So I got on the Kiatechinfo.com site and it was very helpful. I did have to use my PC to initially sign up instead of my MAC. What I found was that the Crank Position Sensor needs to measure between 800-900ohm resistance. I got a reading on my multimeter of 680. I am thinking about buying a new CKPS, I just don't know how reliable this test is. The part is almost $80.00 and of course it is not returnable. I think I might try to find one at a u pull it yard.
I replaced the first large cat on the exhaust manifold, the second cat it clear, which i know is not great but also not bad enough to cause all of these problems.
The coil pack was replaced only once with great improvements.
And yes, the female connectors from the wires leading to the ECM are cracked and need to be replaced.
I would think that these connectors would be more resistant to heat.

[Kevster]

Very carefully look for vacuum leak. center of intake manifold underneath (where it is hard to reach) is where I found mine. Also, what about O2 sensors? They have about a 100-120K lifespan. Injectors? I would pull them and clean the ports at least. Then run some strong seafoam through the intake. I had an 04 Rio with 146K miles and it was badly gunked at the injectors AND the throttle body. It had a clogged cat, and the biggest nightmare was that IACV. Personally, I'd throw it(IACV) in the trash and buy one with fewer miles or brand new, but they are rather expensive. I had 185 psi compression on all my cylinders so yours is low. Low compression can and will cause issues. Worn rings or leaky valves are going to make a problem seem even worse. And Isn't Albuquerque about 6000 ft ? You will have a weak little engine at that altitude. Mine was slow at sea level. Anyway.... Good luck with it.