Mechanics

LOSING SPEED AND JERKING INTERMI

2001 Kia Optima

Engine Performance problem
2001 Kia Optima 4 cyl Two Wheel Drive Automatic 750000 miles

I literally have no hair left to pull out anymore. I have been trying to troubleshoot this issue for so long. ANY help would be very useful at this point.

My Kia Optima 2001 2.4L 4 cyl automatic is having an issue where when im driving I am feeling a loss in RPMs or sometimes, am at 4,000-5,000 RPM and am only accelerating to 20 mph, and then it will boost up to the normal speed if I keep giving or give more gas. It doesn't happen all the time, but it seems to be getting worse slowly. No one knows exactly what it is, I have had a lot of work done to this sucker. The CEL is on and reads a lean fuel mixture in bank 1. I had a problem a year and a half ago where my coils went bad causing an awful jerking when driving, and since then, replaced the coils and all my plugs. Wires probably did not get replaced (not sure). My mechanics dont seem to think coils/wires/plugs are the issue. I replaced one O2 sensor last year, and am waiting on a MAF in the mail to replace that (since my mechanic did a check on it, and it was reading an incorrect voltage). I have used seafoam in the gas tank and regularly use Chevron with techron fuel injector cleaner (about twice a year). I am hoping the new MAF fixes it. I also had a few small vacuum leaks fixed, and the PCV valve was replaced. I did also have to replace the crank sensor a couple months ago. I've replaced all my belts, and I am just running out of resources. At 75,000 miles this thing still runs smoothly other then the jerks while driving. Any ideas? I've heard coil packs, wires, plugs, throttle body, tranny slipping, fuel injectors, fuel delivery, MAF, O2 sensors and cat converter clogging as different problems from similar situations. I will gladly pay for help, but first im waiting on this MAF to arrive (since I just dished out another 100 on it).
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Captgeech21
October 8, 2009.




Does it seem like the trans slipping?

I mean, from what I have read, it sure seems like it could be the tranny slipping. But none of the three mechanics i've taken it too seem to think so. I get the p0171 code for lean bank 1 a lot. From what I read, the o2 sensor is reading a lean mixture which can cause the symptoms of loss of power, jerky accel/decel. I have replaced the MAF now, and it didn't fix it right away (which I think if it is going to, it would do it immidiately, but I could be wrong). I am still testing it for the next day or two. Leaving it cold for a while seems to excite the issue too, or at least it used to, now it seems like it is doing it more often. I replaced the upstream sensor on orders of a mechanic, and don't feel like replacing the downstream if it is unnecessary as its 100+ dollars =-(. Im so broke and in debt I really cant afford to keep paying for a hundred here and there anymore. I also cant afford a new car. I just dont want this thing getting more damage than it is. Im in a conundrum.

Tiny
Captgeech21
Oct 12, 2009.
Is it possible for you to get a sensor from a junk yard? The reason I say that is because if the mixture is lean, the colder the vehicle, the worse the problem will be. And based on your description, that is what happens.

I don't know where you live, but here (near me) there are " U-Pull it" salvage yards. Basically, you tell them what you need, they tell you where to get the part, and you find the vehicle and remove the part you need. Because you do the work, the parts are really cheap. Getting a used O2 sensor isn't what I would want you to do, but it may get you by for the moment.

Let me know if you have other questions.

Joe
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Wow thanks for such a speedy response. I actually found a downstream o2 sensor for only 40-60 dollars new, its pre-wired and it seems like it will do the trick, its a Denso, there is also a Bosch for just over 100. The junk yards here have a minimum 25 dollars for any part pulled, so I figure for 50-100 to get a new, sure fit, I don't mind doing it. So you really think it could be the downstream o2 sensor? I am game to try it, just didn't want to waste my little remaining money on something that doesn't have a high probability of helping. Also, I replaced the MAF, but I got it from this link: http://www.2carpros.com/makes/kia/optima It looks exactly like mine, and the car starts and keeps running fine (until the said issue occurs). Do you think it was a mistake not buying the MAF directly from KIA? their's is 2-3 times as much money.

Tiny
Captgeech21
Oct 12, 2009.
Chances are, if the computer says the O2 sensor is the probem, it is. It sounds like you are getting a universal one for the price. Make sure the wiring is the same because (if I recall correctly) you will need to wire your plug into it. Make sure it has the same number of wires and they are the same color. If the color is different, make sure the directions explain which ones go to the new sensor.

As far as the MAF sensor, anytime you can afford to get an OEM part, you are better off. Remember the old saying, " you get what you pay for.&Quot; As for parts, it's the same. For my own cars, I will go to auto zone or advance auto and purchase cheap parts that come with a lifetime warranty. It's easy to replace parts and they always keep records on their computer of the purchases. When I work on customer vehicles, they get the choice. Usually, they will take the cheaper part. They usually work just fine, but I've had my problems.

Let me know if you have luck with the O2 sensor. As I mentioned, if the computer is picking up the problem, chances are it should fix it.

(I miss the old days with nothing more to worry about other than a carb, points and condenser, vacuum, and compression. If you had spark and fuel, the cars always ran. A few minor adjustments to dewll or the carb and things were perfect again. Things were so much easier.)

Joe

Well Joe, I wish we could get back to those good ol' times. All the computers and sensors, especially on a early 2000 model Korean car are just trouble. Thanks for all the good info. The universal o2 sensor I found was a Bosch, pre-wired to fit sensor, I may give that a try. The problem seems to have become quite a bit less pronounced since adding the new MAF. I will keep you updated daily. Thanks my friend! When I finally get this problem resolved for sure, can I donate directly to you? Or does that not affect you? Or how does that work? Thanks

Ken

Tiny
Captgeech21
Oct 12, 2009.
Ken: Don't worry about the donation if you can't afford it at this time. I'm just glad to help and hope I did. Maybe sometime in the future, if and when, the economy gets better, you'll need help with a different problem and will be able to donate then.

We are here to help people. And it sounds like you are a good one, so I'm happy to have spoken with you. Spread the word to friends about our site. There is a list of outstanding mechanics here to help people. The site owner who started the site is one of the best I've ever spoken to. Let me know how things work out, and good luck.

Take care,
Joe

Joe,

I have already been spreading the word. A few friends of mine have been having car issues, and I have seen these sites before, but never seen one so well put together and with so much help to be had. I will keep spreading the word.

Also, as soon as I can make sure this issues is resolved and I will have transportation I can rely on at least to get my through my master's program, I will be glad to donate. It may not be much, but I will do what I can. Thanks so much for everything, and I will keep you up to date.

Thus far, the MAF actually seems like it may have done the trick. But I am not hoping for too much. Though I have no felt much jerking or loss of speed, I've been afraid to really go out and test it, and the though the trouble code for the P0171 lean code hasn't come back yet, it has stayed off for a day or two before (since I make small trips to work and school). I will update you again tomorrow. Lets hope for the best! Thanks so much Joe!

Ken Lieberman

Tiny
Captgeech21
Oct 13, 2009.
I'm glad you are getting your masters. I've wanted to for years, but with a wife, kids, house. There is no way to afford it.

Thanks for the compliments and good luck!

Joe,

Thanks you for saying so =). I am trying to make sure I get it out of the way now, as I know myself, and if I stop school, i'll never go back! I hope one day you can find the time and resources to get back for your masters.

I wanted to write you and update you on how things went. It took me a while to be able to sit down and do so, because classes have been killer and work has been tough (I work in the computer sales industry and Windows 7 coming out is a busy time).

So far so good as far as any trouble codes. It seems as if they new MAF took care of that. It also isn't acting up nearly as bad anymore in regards to jerks and loss of RPM/speed. However, I do feel a lot of very tiny jerks when driving at lower RPM (usually under 2.5k). Also, I am not sure if I am just imagining it as only happening now, but it seems when my engine is cold, the car often runs very rough for a while, sometimes until I turn it off and leave it, and then start it after class, then it seems to be smoother. But it is noticeable, even my girlfriend in the passenger seat has commented on how rough it feels. It isn't so rough that the car can't drive, and when you put some gas on it, it seems to drive okay, but it just feels more rough than it ever has. If you have any ideas, id be grateful to hear them =).

Thanks Joe, hope all is well.

Sincerely,

Ken L.

Tiny
Captgeech21
Oct 21, 2009.

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