Kia Forum banner

1 - 20 of 37 Posts

·
Registered
Joined
·
17 Posts
Discussion Starter #1
2004 Optima jerking/poor acceleration PLZ help!!

Hey everyone, i have an 04 kia optima with only 18,149 miles on it, but is driving very bad and does not accelerate well at all after it warms up mostly. it threw a cylinder 4 misfire code a while back and hasnt thrown the code since i replaced all 4 spark plugs and the ignition coil for it. i have ordered a pair of new spark plug wires and a camshaft sensor, will be getting them soon in the mail. The person i bought the car from said all it needed was the cam sensor. it drove a lot better when i first bought it and wasnt misfiring or jerking as much and has gotten worse as time has gone on. i notice the engine power really drops once the car is warmed up and has been driven around for 10 minutes or so. Another thing i notice is the engine or exhaust is louder after it warms up and starts the problem of poor engine power. The car jerks only when u push the pedal to 2500 - 3000 and when you are trying to go faster than 30-35 mph. Also the last symptom i notice is it really jerks bad and loses power whenever i have to drive up hill.

Please if anyone can help at all its greatly appreciated as i am scared to take the car on any highway in fear for it being too unsafe and also worried that i could possibly damage the cat converter.
Thanks
 

·
Registered
Joined
·
17 Posts
Discussion Starter #2
My car is a 2004 kia optima 4 cyl. The car only has about 18,500 miles on it. it shot the P0304 code awhile back but has had no codes since and currently has no codes but is still having the problem. All the symptoms it is having now is after the car warms up it has very poor acceleration and struggles. It then jerks trying to go past 35-40 mph and anytime going up hill. It will then start to over heat if going up hill over a bridge for instance and will not go past 30mph. If i drive the car cold right after starting it seems to drive a little better, but when it warms up and starts misfiring or jerking and having horrible acceleration it sounds like the exhaust or engine is much louder..

So far i have replaced all 4 spark plugs and the one ignition coil pack that goes to the 3rd and 4th cylinder (the one furthest from the serpentine belt). i ordered new spark plug wires in the mail and should be getting them by this friday. The guy i bought the car from said it needed a new camshaft sensor so i have ordered a new one too and am waiting to get it in the mail as well.

The first day i bought the car it was driving much better but has seem to have gotten worse since then. I am really tight on money and cant afford to take it to a shop for an expensive fix right now. Does anyone know what else it could be causing this?

Any help is very much appreciated, thanks
 

·
Registered
Joined
·
1 Posts
F for buying one of these "last of the mohican" optimas. I made the same mistake. Is the car the 4cyl or v6? I'm having a hard time believing the car only has 18k miles on it. If this is the case, has it been sitting for awhile?
 

·
Registered
Joined
·
17 Posts
Discussion Starter #5
The car is a 4 cylinder. I scanned with a obd2 when a check engine light appeared it was a p0304 code then went away but still jerks and has horrible acceleration especially after the car has warmed up. It was owned by an older guy and have tracked the miles from car fax. It was driven and serviced for about the first 10 yrs and after that it was driven sparingly but didn’t just sit completely.
 

·
Registered
Joined
·
1,100 Posts
I suggest that you try to figure out why it's overheating, before hanging on any more parts. Have you checked the coolant level at the surge tank, and also at the radiator (if your vehicle has a radiator cap)? Also, does either the oil or coolant show any signs of fluids mixing?
 

·
Super Moderator
Joined
·
6,851 Posts
You might try moving the coil pack from #4 to a different cylinder...Even if it only has 18k on the engine the coil pack may have broken down from the weather... They are cheap on ebay (under $20)
Dave
 

·
Registered
Joined
·
17 Posts
Discussion Starter #8
Thanks for the replies, the engine coolant lev is good it doesn’t over heat normally it only did it when the car would not accelerate past 15-20mph going up a steep incline over the Verrazano bridge I guess because it was only using 2 cylinders at that point cuz of the misfire.. I guess I can try swapping coils to see if anything improves. I already ordered the camshaft sensor and new spark plug wires after I put them in I will not spend any more on parts until a mechanic or someone can figure out the cause of the jerky misfire..
 

·
Registered
Joined
·
17 Posts
Discussion Starter #10
Tried test driving the car after putting the new spark plug wires in and new camshaft sensor.. after about driving fine for a few minutes the engine suddenly lost power to a crawl of only 15-20 mph. Even when the pedal would get pushed to the floor basicly it would not go any faster.
 

·
Registered
Joined
·
21 Posts
you said it was sitting a long time, what about bad gas or a rusted out fuel system? basically i would say take it to a pro and spend 100-200 on diagnosis since you dont really know the history of the car so much. 20000 miles is like hard to believe. theres gonna be some weird problem there becuase of the low kms.
 

·
Registered
Joined
·
1,100 Posts
Tried test driving the car after putting the new spark plug wires in and new camshaft sensor.. after about driving fine for a few minutes the engine suddenly lost power to a crawl of only 15-20 mph. Even when the pedal would get pushed to the floor basicly it would not go any faster.
You need to scan again for codes, because there must be something else going on, beyond just one cylinder misfiring.
 

·
Registered
Joined
·
17 Posts
Discussion Starter #13
you said it was sitting a long time, what about bad gas or a rusted out fuel system? basically i would say take it to a pro and spend 100-200 on diagnosis since you dont really know the history of the car so much. 20000 miles is like hard to believe. theres gonna be some weird problem there becuase of the low kms.

since i bought the car i have gone through 5 to 6 tanks worth of gas. i looked up the history of the car and seen the car was used and serviced the first 10 years of the cars life. the last 4 years it was driven occasionaly. i was thinking to do a last effort of getting some chevron to see if it helps the problem at all, before i take it to a shop to diagnose as i am really tight on $$ right now i dont think id be able to take it in for a little while unfortunately this is my only car and cant really get around and have to use public transportation to go anywhere farther than a few miles..
 

·
Registered
Joined
·
17 Posts
Discussion Starter #14
You need to scan again for codes, because there must be something else going on, beyond just one cylinder misfiring.
i have been plugging in my obd2 in every few days to see if it is picking up any codes but it has no stored or pending codes which is frustrating. the only code it ever had since i had the car was a p0304.
 

·
Registered
Joined
·
1,100 Posts
i have been plugging in my obd2 in every few days to see if it is picking up any codes but it has no stored or pending codes which is frustrating. the only code it ever had since i had the car was a p0304.
There are not many issues which can produce the symptoms you describe, without setting any trouble codes. Two things that come to mind are a plugged exhaust system (cat, muffler, pipe), and a bad crank sensor (which sometimes doesn't generate a code). You can test for a plugged exhaust by removing the upstream O2 sensor, and taking it for a short drive to see if the symptoms are noticeably reduced. This would of course be loud, so you'll have to decide if you can get away with making a racket for a few minutes.

Unfortunately, a bad crank sensor signal cannot be diagnosed without a scope. So although I previously recommend against hanging on more parts, in this case having a shop check the crank sensor signal would probably cost more than it would to buy the part. So replacing that sensor would likely be the best way for you to proceed.
 

·
Registered
Joined
·
17 Posts
Discussion Starter #17
Okay so for removing the upstream o2 sensor , I want to try and see if it drives better but do I have to remove the sensor completely or can I just disconnect the wire to it to see if the car accelerates better?
 

·
Super Moderator
Joined
·
9,473 Posts
Okay so for removing the upstream o2 sensor , I want to try and see if it drives better but do I have to remove the sensor completely or can I just disconnect the wire to it to see if the car accelerates better?
To assess whether you have a choked CAT, remove the O2 sensor from the exhaust allowing it to vent the exhaust gas through the open O2 port.
 
1 - 20 of 37 Posts
Top