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Intriguing problem - engine rough idle & hesitation - P0300

168K views 25 replies 14 participants last post by  stinkyskibum 
#1 · (Edited)
Hi everyones, Im newly registered here after a couples year of reading helpfull tips here.
This forum has been helpfull since I got my 2004 Rio RXV with/AT two years ago.

After a couples day of search here, I did not find a very similar case to my problem.

# 1 Symptoms/problems
The car as 85,000 km on the odo (50,000 miles).
So, here it is...It started in beginning of August 2011..rolling on the highway by a beautifull summer noon, speed was around 60mph / 100 kmh then I sense a sudden hesitation in the car motion.
It was for a very brief period like 0.1 second. Like if I would have very rapidly have let off pressure on gas pedal and then reapply it.
It did it 3-4 times during the 75km trip home.
Let me tell you I was stressing as my newborn was in his childseat and with no cell phone on board.
My girlfrien used the car intown for 1 weed until the Check engine came on.


#1 Fix
I sent the car to my thrusted mechanic garage, he read the codes P0302, P0303 ( misfire cylinder 2 & 3)
So I told him to suggest me something...we opted to start with the spark plugs first and also erase the codes.
The car ran fine except for still small hesitation while rolling.

#2 Symptoms/problems
One week later We are now mid August... my girlfriend used the car to go to his parents in the neighbor town ( again 75km ).
Almost arrived at destination the car started to hesitate like never before...a lot of stumbles and ckeck engine lighted again....but this time the engine was running with the computer in safe mode so not much power.
Very frighting when it happen on the highway with a kid onboard.

#2 Fix
There a friend mechanic read the code and still P0302, P0303 ( misfire cylinder 2 & 3). So he tested the plug wires with a splash of water just to find they were no good anymore.
So changed the wires....damn problem was still there engine was running very rough. So we did changed the coils pack....that did the job car ran great.


#3 Symptoms/problems
So, coil, wire, plugs are changed, no check engine. My girlfriend decided to come back home. Midway (km 20 of 75 ) Hesitation again...Damn and Damn !!...the mecanic told me the only thing he can think of is bad gas.

#3 Fix
I did put a can of gas treatment in thank with fresh gas.

#4 Symptoms
Since 1 week from now the car is acting stangely, sometimes it is running ok than hesitate a bit. But 4 days ago it started to idle very roughly when in D or R. When arriving at a stop or red light, SOMETIMES the engine want to stall. Then a couples minutes after the check engine light on.
When it want to stall if i put it in Neutral and give it a bit of gas is help to keep the rev. If i dont do that , the engine keep reving slower and slower with a lot of vibrations ( like a harley davidson engine on idle). Keep in mind that it is an intermitent problem.
The check engine code is P0300 (multiple cylinder misfire )

#4 Fix
I brought a spray can of Throttle body cleaner that i used completly through the mass airflow as per the recommendation of my thrusted mechanic....did not seem to help a lot but it seem the problem bay be lessen than before.
So he suggest me to unplug the car battery to erase the code..and possibly reset the computer. My mechanic suspected the bad idling is comming from the SAFE MODE in the computer.
That fix WORK. Since the 2 last days, car go well for 4-5 km then bad idling start and car as difficulty reving and has no power, I just reset the computer with the battery unplug method then Im good for another between 1 to 20 km... again and again.


Now im seeking for help from the community.

Thanks in advance.
Daniel
 
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#2 ·
Wow, one of those irritating things that could be a single "hard to find" problem, or a group of problems that just coincidentally appeared. Almost sounds like a bad connection somewhere but if all you're getting is misfire codes, I would look at the crank sensor and cam sensors first. Pull them and Clean them and check the connectors for corrosion. Check engine ground to body. On my 2004 Base Rio it is on passenger side from body to timing cover bracket on engine. What did you gap the plugs at? A lot of posters here agree the gap needs to be on the low end of the factory recommendation (about .031"). Mine worked best at .027. If you have a fuel issue or leak, you should be getting a few other codes besides the misfires (O2, lean or rich, intake leak, CAT issue). A plugged fuel filter, or injector or 2, might show up as an intermittent misfire, but the way it runs okay for a few miles then appears out of nowhere makes me think wet/bad connectors, or bad ground somewhere.
I got 303/304 codes when my plugs were gapped too high. I also saw 301/303 codes a couple times before I discovered I was one notch off on the exhaust cam timing (after replacing my timing belt). Maybe you ought to double check your timing...??? And the next thing that comes to mind is a compression check just to verify something odd isn't happening inside the engine.
Hmmmm... check ECU connections/ fuses/ battery voltage, and connectors. Load test it. I know I am reaching a little but I have read all sorts of crazy things happening with a bad battery or connectors. Worth a look....
Go to kiatechinfo.com and register and study their troubleshooting guides and do the easy checks first. Maybe you'll get lucky and see something there that applies to your situation.
Anyone else see something I'm not?
 
#3 ·
Oh yes! and the Idle air control valve will mess up your idle! Clean that thing first! It is mounted on the front of the throttle body under the air cleaner assembly behind the ignition coils. Take it off and clean it out with carb cleaner until the little valve gate inside slides easily. Thanks Ronjohn, I heard you shout that all the way across the US!! :)
 
#4 ·
#5 · (Edited)
Hey daniel, Kevster is right on track like he says WOW it could be anything. Do what kevster say's check the cam and crank sensor and fuel pressure and please don't forget about cleaning the IAC valve it might help and the electrical connections to the ecm. My problem started with a p0304 and p0300 turned out to be a blocked 2nd cat after all i did fuel pump , fuel filter plugs , wires pcv and hoses. It didn't go away untill i broke out the 2nd cat (loss of power), but you don't have that issue. Check out Kia Global Information System (KGIS) I don't think its free in canada might have to pay it can help. But give it a try listen to kevster he has been there and done that I wish you luck with your problem. Reguards ronjohn once again thanks for your insight kevster
 
#6 · (Edited)
An update to everybody. My sparkplugs are gapped all right. 0.039 to 0.043 as recommended.

I actually found the cause to my symptoms...
When the engine is running rough, Im actually running on only two cylinders. I have no power going to the connector pluged in the ingition coil 2-3.

So I tought I had a bad connector, so chopped it to change it with a junkyard one....BUT I tryed to mesure voltage on the chopped wires when ignition is ON but there is no juice !!!

So im left closer to find the real problem. But now the symptoms are no more on and off ... it now only run on 2 cylinders.

Does someone know where the power to this connector is coming ?

Can the problem be the ecm or a relay or the Ignition control module embedded in the ecm ?


Thanks again.

Daniel
 
#7 ·
Daniel...
You seem to be doing a good job at diagnosing your car. The next step would be tracing the wiring harness from the coil to the ECM. "kiatechinfo.com" should be available to you in Canada. You need to be running windows (XP/Vista/7) and Internet Explorer (6 or higher) and have Adobe SVG (scaled vector graphics) installed.
On kia's site there is a complete wiring diagram available showing plugs/sockets/connectors. Sounds like you have a corrosion problem in your wiring. The ECM does control the coils but they don't fail very often.
Dave
 
#8 · (Edited)
:) Problem is fixed....guess what was the problem !

It was a wiring problem. The white wire going the the connector for the coil 2-3 was splittting due to stess and fatigue. It broke at the right angle corner exactly where the wires harness attatch to the radiator fan shroud. I suspect a bad design because the engine move front and back due to torqe and the main harness is attached the front body of the car so wires have to flex at all times. So I welded back another wire and car run now like a new one...sould say like a normal 86,000km car.

What a lot of headaches due to the fack that the wire was very slowly splitting with problems becoming worst and worst...at the end problem was easier to find as the wire was completly separated in the insulator.
 
#9 ·
Hey RonJohn..
Here's another one for your Rio "book"....

DANBAT...
Sorry you had to spend the money before finding the problem...SEE... your registering helped! We ARE glad you joined our community...
Don't stay away!
Dave
 
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#12 ·
Don't be too hard on the guy....sometimes these cars mislead you with weird symptoms and even though the computer throws codes at you, the issue specified in code explanation is not always EXACTLY the source of the problem. If all the problems were simple to diagnose and fix we would have little use for fancy diagnostics machines and experienced mechanics. I personally like to fix my own stuff, both as a challenge and as a money saver. But I spent many frustrating hours fixing my Rio. Learned a lot from that car!
 
#15 · (Edited)
exact same problem as DanBat

I have all the same symptoms as the original post so I started checking the wiring that goes into my cylinders. There is a lot of greenish white powder on my wires and I'm having trouble trying to locate where the problem is. There is a plug where the wires for it and the wires for cylinders 1 and 4 are bundled together. I tried using my electrical manual but it's a little hard to locate. I THINK, based on my manual, that its the plug for my cam shaft position sensor but I'm not really sure. There's so little room to work in the engine that I'm having trouble lining up what all these wires are going to. I did notice, in the connection where the wiring directly into cylinder 2 and the wiring that goes down into the car, that there are some wiring that has been exposed and appears to have some discoloration(rust maybe). I'm not a mechanic so I'm a little confused on some of the lingo but I do have both the electrical manual and the mechanical manual (original kia service manuals) so they kind of explain it.

EDIT: It is the camshaft position sensor, I just found it.

EDIT: (again): I'm thinking ignition coil now. After talking to yet another mechanic (this one seemingly aware of the difference between his ass and a hole in the ground) and looking up more information it's starting to sound very convincing.
 
#16 ·
additional info

I have taken this car to every mechanic I can think of, including the kia dealership, and none of them have been any help except for the guys at pepboys who actually told me about cylinders 2 and 3 not firing. They also mentioned that my MAF and TPS will stick to some random voltage(that may not have been the word he used, sorry my memory sucks).
 
#17 ·
julia do check the low voltage connectors on the coil pack as cylinders 2/3 are on the same connector. From other posts the connector gets brittle and breaks and gets loose thus the connection will not fire cylinder 2/3 just something to check what code are you getting? on the coil pack connectors cylinder 1/4 fire together and cylinder 2/3 fire together its called wasted spark. let us know If you find anything. I know they dont have alot of wire to them connections very thight Reguards Ronjohn
 
#19 ·
I have the same problem as OP. I took it to the mechanic today and they mentioned cylinders 2/3, maf, as well as tps. My rio hesitated for awhile, now it won't rev past 2500 rpms. It revs up to 2500 normal then drops down to idle rpm over and over forever. Lol. Car tops out at 15 mph on flat land. I know the mechanic is taxing when he told me $200 for a maf sensor. So I'd rather find the prob sooner than later. Just like everyone else with car proplems, because later usually means $$$. I'm going to go get the exact codes from him tom and maybe unplug the battery and clear the codes before I hand him cash. I will keep you guys updated.
 
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