2004 Kia Rio HELP with LEAN condition

Tiny
DOCHERA
  • MEMBER
  • 2004 KIA RIO
  • 4 CYL
  • FWD
  • MANUAL
  • 84,000 MILES
I recently bought this 2004 kia rio, with the check engine light on. (I know dumb move but it was only $2300) so first things first, got it scanned and it said (lean mixture, random misfire, knock sensor).
I changed the plugs and wires, oil, topped off the water and changed a belt. I also looked at the timing belt which looks good!
Things I've done since include, (replace MAF, replace TPS, clean and check idle air control valve)
ok so I have a rough idle and intermittent missing while driving. I hooked up a "live data" scanner and recorded info.
Immediately a couple things jumped out at me.

1 is BOTH o2 sensors read a lean mix, when I add propane to intake they both jump to.9 volts then back down around.03 V (so I'm fairly certain the o2 sensors are NOT the problem.

2nd thing I noticed is the engine load at idle is around 40-50% WHOA NELLY! Seriously whats up with that? Fuel trims are very high 20-30% range

I removed exhaust manifold, and valve cover, all looks good. There. I checked all vacuum lines and they all seem connected and in good shape. Fuel pressure holds around 45psi with key on, also with engine running.

So at this point I'm assuming I either have an enourmous vacuum leak I cannot detect, or possible the map sensor is bad. Anyone have any ideas or something else I should be looking for with the live data. Remeber I just bought this car so have no idea of its maintenance and service history
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Sunday, May 31st, 2009 AT 4:46 PM

9 Replies

Tiny
RASMATAZ
  • MEMBER
A lean fuel condition can be caused by:

* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (Use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (Try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)
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Sunday, May 31st, 2009 AT 5:37 PM
Tiny
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Thanks for the reply, but

I REPLACED the MAF so its not that.

Its a 2004 kia rio and has no EGR valve apparently.

I tested the fuel pressure at idle and its 45 psi and holds steady.

I ran a bottle of lucas injector cleaner through fuel system, didn't help.

Tried to run a vacuum test and it did seem low but I can't get the idle to hold steady or 2000 rpm to hold steady enough to get a good read, I did only get about 7 in/hg though which seemed low but I'm not sure I had it hooked up right. It was coming off an intake hose leading to some round inline device with a wire harness then from there it goes to a small canister, I used a T connector to plumb in the gauge but the vacuum attachments with the guage are way smaller than the vacuum hoses on the car so I may have had a bad setup.

I checked pcv valve, rattles around and only lets air pass one way.

Only two places I havent checked are the intake manifold and throttle body gasket, becasue I heard once they are removed I have to replace them, and both are "speacial order" gaskets they don't have here in town so I was trying to work around those two possibilities in the mean time.

Another thing, sometimes the car will rev up to 2000-3000 rpm when it should be idling, then sometimes it will drop out like I turned the key off but if I save it with gas pedal it will then idle around 800-1000 but very rough and lean.

Can anyone tell me exactly what sensors the car uses to determine the "calculated engine load" I assume it uses the TPS, MAF, and MAP sensors for this calculation. And since both TPS and MAF are new, leads me to think its the map, but I'm sick of assuming and being wrong ! LOL

Thanks.
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Sunday, May 31st, 2009 AT 6:21 PM
Tiny
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Cleaned and checked all fuel injectors. They were a little dirty but once re-installed on the fuel rail I cranked the engine a few times all four fired a nice cone shape. (Was like watching the belagio fountains LOL)

Seriously though any help would still be appreciated, I'm begginning to wonder if it could be a valve problem. I took the valve cover off yesterday and everything looked clean and nice, but I don't know enough to tell if there is a problem with them. Any way to tell other than a compression test.

Why does my car have a MAF and MAP sensor, but on my "live data" it doesn't seem to have the manifold pressure listed. I tried the scanner in my nissan pathfinder and it showed manifold pressure!
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Sunday, May 31st, 2009 AT 8:15 PM
Tiny
RASMATAZ
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To find a valve problem you need to perform an engine compression and cylinder leakdown tests.
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Sunday, May 31st, 2009 AT 9:40 PM
Tiny
DOCHERA
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Ok I performed a second vacuum test, this time instead of using the "T" fitting I simply bypassed the canister system entirely and put the gauge right on the end of the vacuum line to the intake manifold. This time at idle I was getting about 17in/hg, then when I'd rev to 2000 RPM it would dip momentarily then climb to 20in/hg and both held pretty steady +/-2in/hg. So I'm thinking I don't have a vacuum leak.
After resetting the codes I let it run and revved it a few times.

The first code to come back was p0507 " idle control system RPM higher than expected"

the second was p0300 "random misfire" and

the third was p1166 "lambda o2 sensor bank 1 limit"

the live data during this period was showing
STFT at about 22 and LTFT at 17.1 both o2 sensors were about.030V at idle and would breifly jump to.8V when I would rev up but then they would drop again even if I held the rpms up.

"calculated engine load" was about 25% when at idle with A/C off so that seems high to me.

Also the TPS sensor says 13.7% at idle with no pedal movement and 84% at WOT

That doesn't seem right to me but I read it could just be the odb-II scanner misinterpretting the voltage of the sensor. So I hooked it to my nissan pathfinder that runs fine and it said TPS 1.2% at idle and 87% at WOT (not sure any of that matters LOL)

so what the heck. I also noticed on my nissan it gave me a manifold air pressure reading in live data, but on the kio I'm troubleshooting it did not, even though I see a map sensor on the intake. Could it be that simple that the map is out? (No code for it) remember the MAF is brand new!

Thanks for any suggestions
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Sunday, May 31st, 2009 AT 10:34 PM
Tiny
DOCHERA
  • MEMBER
Ok so I changed the plugs to mgk gp/platinum OE type and gapped them at.30 still have the same running condition.

Current codes are

P0303 cylinder 3 misfire
p1166 lambda con. At L/R Limit-B1
p0304 cylinder 4 misfire
p0325 Knock sensor
P0121 Throttle/ Pedal position sensor A circuit range/performance

Freeze frame data at cylinder 3 misfire is as follows
fuel sys 1 Closed loop
Calc Load % 23.1
ECT (f) 100
STFT B1 (%) -12.5
LTFT B1 (%) 17.1
Eng RPM 2373
Veh Speed MPH 0
Spark ADV 11
Internal Air TEMP 80 (Farenheit)
MAF (lb/min) 1.082
TPS % 14.1

Any more suggestions anyone? This thing is driving me nuts
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Monday, June 1st, 2009 AT 6:40 PM
Tiny
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Compression tested the engine.

Here are my results.
Cylinders:

1- 220 psi
2- 225 psi
3- 100 psi
4- 220 psi

so obviously the problem is in cylinder 3

then I poured a capful of oil in and repeated the test on cylinder 3

this time got around 120 psi but not a huge jump so am I to assume I have a burned valve.

With that being said I know I have to pull the head to get to the valve. My mechanic (which isn't very helpful) told me he usually sends the heads out and gets different ones to install, but he wouldn't tell me where to get the head. He also said maybe I should just throw a used engine in it. I found used engines around $1000 haven't located heads.

So that being said, what should I do. Can I do it myself. (I never have, done either but I'm pretty quick at picking things up to and worked on alot of engines, this one seems especially simple to work on, so I'm tempted to try)

anyone know a good place to get the head or used engines?

How hard would it be, labor time isn't much of a problem just the complexity of it all.
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Tuesday, June 2nd, 2009 AT 3:02 PM
Tiny
RASMATAZ
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When you inject the oil and the compression rises it means its a ring problem not a valve
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Tuesday, June 2nd, 2009 AT 3:37 PM
Tiny
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Ok I pulled the head off, (8 hours for a newbie, sheesh) lol

ok so even with only a 20 psi increase you think its the ring.

Obviously I want to be sure I already have the head off and found someone in town that will rebuild it for me for about $300-$600 depending on parts but at this point how hard is it to get to the rings,

it went from 100psi to 120 psi.

Thanks again for the input
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Wednesday, June 3rd, 2009 AT 1:28 AM

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