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doctor-d
doctor-d, ASE Certified Technician
Category: Kia
Satisfied Customers: 756
Experience:  ASE Master, Auto Shop Owner
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Kia optima 2004 LX 2.4 liter hard to stop,does not

Customer Question

Kia optima 2004 LX 2.4 liter hard to stop,does not decelerate like it should.Rpms jump when coming to a stop and car wants to go forward.Have tried everything I could and tracked down every angle of this problem from Alldatadiy website but nothing.
Submitted: 1 month ago.
Category: Kia
Expert:  Amedee replied 1 month ago.

Hello and welcome!

My name is ***** ***** I can assist you with your question.

Expert:  Amedee replied 1 month ago.

I am very sorry your having this issue with your vehicle.

I will try my best to answer all of your questions.

However, before we get started, please let me mention a few things.

1. If at any point you would like to speak on the phone, please feel free to request a phone call on your end and I can call you right away.

2. If you dont understand any technical terms or anything that I mention (component tests or theory or operation), please let me know and I will provide you with a more in debt explanation or answer.

3. Please understand that I am here to help you any way I can.

Expert:  Amedee replied 1 month ago.

Is the check engine light on? Are there any codes in the computer?

Would you be willing to speak on the phone?

Customer: replied 1 month ago.
No there's not and sure yea I can
Customer: replied 1 month ago.
Nevermind we'll just talk here,proceed with your questions please
Expert:  Amedee replied 1 month ago.

Have you checked the air intake snorkel for cracks/rips? If there is air entering the engine that is not accounted for by the computer, it can and will cause this issue that your having.

Customer: replied 1 month ago.
The air filter assembly? If yes then yes I have.
Expert:  Amedee replied 1 month ago.

I am talking about the air intake snorkel from the mass air flow sensor to the throttle body.

Customer: replied 1 month ago.
thats what I'm talking about
Customer: replied 1 month ago.
Let me take one more look before we proceed if you dont mind
Expert:  Amedee replied 1 month ago.

NO problem. YES, please check.

Look close for any cracks or rips or tears where air can enter the engine AFTER the mass air flow sensor.

Customer: replied 1 month ago.
Almost done
Expert:  Amedee replied 1 month ago.

Ok

Customer: replied 1 month ago.
Ok so I went ahead and disassembled the whole thing and bent and looked in every crevice and no cracks then made sure all fasteners that hold the sections together were tight
Expert:  Amedee replied 1 month ago.

Ok excellent! As long as it is securely fastened on either end, you should be OK.

So your saying that the MAF was replaced correct?

The engine bogs down under a load?

Customer: replied 1 month ago.
No I didn't replace cause I checked it as Kia instructions told me to from Alldatadiy.com
Expert:  Amedee replied 1 month ago.

Ok, the MAF sensor is the number 1 input to the PCM for injector pulse width. Your MAF sensor might just be faulty.

Another possible cause would be plugged exhaust or incorrect valve timing causing this low power or hesitation condition when accelerating.

Customer: replied 1 month ago.
When coming to a stop it takes it slower for the rpms to come down than it used to, plus as this slow deceleration occurs the rpms jump like the cars saying "no I dont wanna stop I wanna keep going" like a hiccup
Expert:  Amedee replied 1 month ago.

Got it!

I would suspect a faulty throttle body, sticking throttle cable or faulty TPS causing this condition. If the TPS was replaced, monitor the TPS voltage while this happens. It should stay under 1.0 volt with the throttle closed.

The only other possible cause would be an air/vacuum leak causing a higher than normal idle.

Expert:  Amedee replied 1 month ago.

I am glad I can help!

Please don't forget to honor your good faith deposit by rating my answer as "5 STARS or SMILEY FACES" for assisting you today.

Keep in mind, we can still continue this conversation at no further cost to you even after you rate my answer. Just reply back to me using this page and I will get it and get back to you ASAP!

Also, if you are a member or if you have a subscription to the site, you still need to rate my answer in order for me to get credit for assisting you with your question.

You should see the rating system towards the top of the page.

Please let me know if you have any further questions.

Customer: replied 1 month ago.
I checked exhaust for it being plugged and when I revved the engine like instructed it went up and not backwards like its suppose to so Im good there.Now wouldn't the CEL light come on if MAF was defective? I am losing like 160 mpg.You would think the light would've gone on if I'm losing that much gas.Plus timing has been verified all around.This past weekend I cleaned the valve lifter oil galleries to see if they were culprit but problem still exist.
Expert:  Amedee replied 1 month ago.

If the MAF signal never goes outside of the "window" that the computer is looking for then no, it will not set a code.

Customer: replied 1 month ago.
As I explained in the "what have you done so far" section I cleaned and inspected the throttle body already,have done all electrical inspections for TPS and other switches,solenoids and sensors.Also verified no sticking cable already.Also you say "under 1v when closed" is incorrect.It's actually 300mv-900mv when closed.
Expert:  Amedee replied 1 month ago.

What is the engine vacuum at idle?

Customer: replied 1 month ago.
Vacuum is 20 hg which 19-21 hg isbmy specs so I'm good there.It pops down to 0 then hits 24hg then stabilizes at 20hg
Customer: replied 1 month ago.
Needle is steady
Expert:  Amedee replied 1 month ago.

And the IAC was replaced correct?

Customer: replied 1 month ago.
No I checked.I dont just replace,I thoroughly diagnose.Ohms are correct on both open and close side of the coils.Continuity is good from ecm to IAC as well as no voltage drop
Expert:  Amedee replied 1 month ago.

Excellent!

So where is the air coming into the engine causing this high idle?

Expert:  Amedee replied 1 month ago.

Were you able to check the fuel trims?

Customer: replied 1 month ago.
34;Where is air coming into engine causing this high idle?" huh? Where did that come from? I never said anything like that.lol Hey just don't worry about it I'm gonna call a mechanic tomorrow thanks have a good day.
Expert:  Amedee replied 1 month ago.

Sounds good!

I am glad I can help!

Please don't forget to honor your good faith deposit by rating my answer as "5 STARS or SMILEY FACES" for assisting you today.

Keep in mind, we can still continue this conversation at no further cost to you even after you rate my answer. Just reply back to me using this page and I will get it and get back to you ASAP!

Also, if you are a member or if you have a subscription to the site, you still need to rate my answer in order for me to get credit for assisting you with your question.

You should see the rating system towards the top of the page.

Please let me know if you have any further questions.

Expert:  doctor-d replied 1 month ago.

You have a big vacuum leak or a bad MAF. Unplug the MAF and note engine performance.

OR the timing belt jumped, or someone screwed up installing one?

You need to start with the basics! don't just replace parts as it makes more problems and harder to diagnose.

Customer: replied 1 month ago.
Have you not read the previous conversation with the other guy?If not please read it.I requested another mechanic cause he seemed to not communicate well and most of your answers for questions or assumptions are written there.So please go over that and get back with me thanks
Expert:  doctor-d replied 1 month ago.

Sir, No one will be able to help you if you cannot give proper diagnostic information. I did read the entire story. Have a great day and good luck with that!

Expert:  doctor-d replied 1 month ago.

you've spent more on your car then it would have cost to have it repaired at the Dealer. Good day

Customer: replied 1 month ago.
I did give proper everything and like I said all things I have already done are in the "what have you done already"section when starting the process.You assumed I just threw parts at car but nowhere do I say that.If you knew about the MAF on my car you would also know that disconnecting it would make it die.Also there are no CEL lights at all.Timing belt and all is correctly done.
Expert:  doctor-d replied 1 month ago.

Start the engine with the MAF disconnected. And see how it runs after 30 sec or so

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