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Losing acceleration and no throttle response

184K views 28 replies 12 participants last post by  Scruffs90 
#1 · (Edited by Moderator)
I'm losing throttle response at a much lower RPM than I was. The problem started suddenly, not gradually. The MAF looks good and I checked the TPS and got a steady graduation of resistance but I'm not sure what the Ohm range is supposed to be it was reading between 1.5 and 2.2 ohms with the multimeter set to 20K.

When I opened the throttle by hand I held it wide open and it revved up some and then began to fall almost back to idle before it picked back up all the while I was holding it open. Also, it's idling high. The check engine light came on when this problem started and I had the codes read and got 172, 121, 170, and 101.

If anyone knows what the ohm range is supposed to be for the TPS or any other information that could help with this problem it will be greatly appreciated.
 
#2 ·
Don't know what year and model you have but here is some good info Kia Global Information System (KGIS) will help with your problem. Service manual info just like techs at dealership get its free just have to register. Please fill out your profile this will help everybody on site to help you better good luck. My 02 rio book says ohm readings TPS (0.71~1.3kohms) @ idle 0.3-0.9v. (2.2~3.4kohms) @ full open 4.0-4.4v for code 121. 101 code is for maf 170 and 172 point to tps and maf hope this helps
 
#4 ·
I'm losing throttle response at a much lower RPM than I was. The problem started suddenly, not gradually. The MAF looks good and I checked the TPS and got a steady graduation of resistance but I'm not sure what the Ohm range is supposed to be it was reading between 1.5 and 2.2 ohms with the multimeter set to 20K. When I opened the throttle by hand I held it wide open and it revved up some and then began to fall almost back to idle before it picked back up all the while I was holding it open. Also, its idling high. The check engine light came on when this problem started and i had the codes read and got 172, 121, 170, and 101. If anyone knows what the ohm range is supposed to be for the TPS or any other information that could help with this problem it will be greatly appreciated.
I have a similar issue. Throttle response goes away at about 2000rpm. Can't accelerate any faster than that rpm will allow in any gear. Acts like it's starving for fuel. Engine never stalls and will start and idle fine.
Fuel filter has been replaced and no engine light is on. MAF sensor was replaced about 2 months ago in response to engine code at that time.
Now, I'm thinking TPS but don't know how to check it or even where it is to replace it.
 
#7 ·
Start with easiest checks first

I am a newbie at Kia's, but have been a car tinkerer for years, and right up front, this sounds like an air leak, or possibly some bad wiring. Run the car and spray some carb cleaner around the intake manifold and see if idle doesn't change indicating a leak. Your error codes sound totally cross related as if you have some bad wiring to ECM, so check for damage or bad grounding on all sensor wires/harnesses. Clean the MAF if you haven't already (especially if you use an oiled filter). Good luck, all those codes together is confusing. o2 says too rich...TPS has fault...fuel trim out of range...MAF has error... hmmm.
The possibilities are endless.... My best guesses are: intake leak, bad MAF sensor, timing off, or plugged exhaust system (cats).
 
#8 ·
Update

Mine had no check engine light, hence, no codes to check. The first shop I went to spent 3 days swapping out parts in hopes of fixing the problem.
On my way to the second shop, the engine light came on and logged the following codes: 116, 121, 140, 101. The MAF had already been changed and the other issues were checked and no problems found. The shop reset the computer and now it runs fine. Go figure!
 
#9 ·
2001 Kia Rio - Idles great, but as soon as you give it a normal foot pressure to accelerate it will hesitate and then drive on.. I even driven on the highway and when I slow down and try to boost back up it will hesitate again... My engine light codes say MAF sensor. But it did that over the winter and I changed the plugs, wires and run fuel cleaner in it.. it worked.. but now its doing again, Its Spring!
 
#10 ·
I'd clean the MAF sensor and replace the injectors if you have the money. Rebuilts are about $40 each. Of all the things I have done to my Rio, I found throttle body cleaning, new(rebuilt) injectors, and gapping the plugs at .026 worked the best. Injector cleaner helped but takes too many tanks to get good results. I am still searching for better mileage, but at least it runs good. And all the above are easy fixes you can do yourself.
 
#11 ·
Mine is doing the same thing!!! Help! I have changed the fuel filter and I can start up fine... but it does just what you stated... any fixes.. auto parts store did a check and it came up MAP sensor.. I thought fuel pump, but a friend at the auto parts store said a fuel pump would not let you have a good RMP in park... I do hear air coming from the exhaust when I hit the gas pedal... could this be a leak.. once I drive and stay drive its fine... but when I come to a stop and start to move I have to do really slow and then it runs.. I did notice that when I floor it I will get a hesitation too..
 
#14 ·
Hey kevster, I didn't get the exhaust down yet working alot of overtime but when i seperated the cats 1 and 2 i got my rpm's back and it idled great so it could be the #2 cat or muffler not sure yet but seperating the cats got me in the right direction check out my therad 2002 rio p1166 p0300 p0304 to see what i did and all the great help i received all exhaust components are original 134000 miles on car so somthing is blocked really hopes this helps you out.
 
#15 ·
Thanks Ronjohn. Just curious. When I dropped my cat(2nd one) I stuck a wet vac hose in to see if it might pull anything out of muffler, but it was clean. I have a large powerful vacuum and it didn't even change tone when I stuck hose in there. Any restriction would have made it pull harder and change tone. I went to the tail pipe and did it the other way and same thing. No change. No restriction. Somethin you might try to see, without dropping the whole rest of the exhaust. Maybe you'll get lucky and pull a bunch of debris out the front side... :)
 
#16 · (Edited)
no my pipe from 2nd cat to muffler is broken (hangars) have new pipe was hopeing to change this weekend but it's raining outside going to replace everything from 2nd cat to tail pipe when i can (weather permitting) all i know is when i disconnected between 2 cats my car came back to life that should eliminate the 1st cat just leaves 2nd cat or muffler what's the best way to break the bolts on cat i have no air tools? like I said thank you very much for your help I really mean this. And my son thanks you also he is a computer geek not much for wrenching.
Ronjohn
 
#17 ·
Kevster...
Inside the catalytic converter is a ceramic with a very tiny "honeycomb" structure. Made that way so as to increase the square inch area the exhaust has contact with.
As far as vacuuming out the "dirt" you can't... the poisoned CAT won't let go of it.
Here's a great site to see and understand a CAT...
All Catalytic Converters - How do I know if my catalytic converter is defective?
If you can get a steel rod into the CAT you can break up the ceramic honeycomb and then dump (or) vacuum the broken parts out (only do this if the CAT is plugged as you may not "pass" a car inspection if you have one in your area). I see you live in California so you WILL NOT pass inspection.
The second CAT is NOT monitored by the engines ECM and "gutting" it won't hurt the car's performance (if plugged the performance will improve) but again you won't pass.
I'd try driving it temporarily with the 2nd cat disconnected...It will be noisy but IF the car performs much better the CAT is plugged and you'll then need to replace it.
Dave
 
#19 ·
Thanks Davesspectra, I already combed the internet and read several articles to gain more knowledge on cats, including the one you mention. Awesome article I might add!! I already passed smog so knew at least one of my cats was good enough to function at least somewhat, but was worried I might still have some restriction. Here in CA they put car on dyno and run it at 2500rpm (under load) to actually simulate real world cruise conditions for the smog test. My reasoning was, it might pass at that minor load/rpm, but display bogging under a higher load if things were starting to clog. I fully intended to break out the ceramic on the second cat, but it was obvious it was not clogged. I could see light (easily) through the honeycomb and my vacuum test tells me if there is any restriction it is so small it won't matter. I actually broke out a cat on an 85 Nissan pickup (2.4L engine) many years ago and it actually passed smog afterwards!! Course it was almost new and CA didn't use the new dyno testing in those days... but it passed.
When I ran mine with the 2nd cat out, it really wasn't that loud, I expected far worse. Anyway, After reading all I could find on cats and thinking too much, I theorized my second O2 sensor was funky and might be freaking out my mixture but not setting a code, so that is why I replaced the O2 sensor today. I drove the car 18 miles today and it seems WAYYY BETTER, but I don't want to get too excited cuz its a bit premature after only 18 miles. I want to get her out on the highway and push up some hills to see what it does. Then I will be able to really see a difference if any. Oh and maybe I should clarify my vacuum suggestion. I don't expect it to clean a cat (especially a "poisoned one", of anything bonded in the honeycomb. I just thought it MIGHT remove any rust flakes or broken bits from previous cats, or such... from the muffler. Mostly I was using the vac to see if it (muffler/tailpipe) was restricted. On a large powerful vacuum...even a window screen placed over the end will make it change tone slightly as vacuum "pulls" harder from the added resistance. More resistance= more noticeable change in tone. And just for added clarification, my Rio would always rev to the moon when sitting in my driveway... I shoulda known it wasn't clogged. But my imagination got the best of me! :) As of today, my Rio seems to be running sweet....at 141K miles on the odo.
 
#20 · (Edited)
I cleaned the IAC valve and MAF and throttle body on my 04 and it cleared almost all issues with hesitation up >> http://www.kia-forums.com/1g-2g-2001-2005-rio/60544-hole-airbox-3.html

I did eventually replace the MAF sensor though cleaning it can help for a little while, if the issues persist, you should replace. also make sure your valve cover gasket is not leaking oil into the spark plugs or anything, at 108,000 after buying the car from a large dealership around here that claimed all maintenance was done up to 50,000 miles, the stock valve cover gasket was found brittle as hell, and i had oil leaking into the spark plugs that would cause these issues combined with the IAC and MAF and TB being really dirty due to that hole in the airbox, i believe, and I also think there is no fuel filter on my 04 ;/

ill take a pic of what im taking about the valve cover gasket and post up here ina few hrs: I just changed it last night :)




more pics next post.
 
#21 · (Edited)


The pictures show a brittle old gasket, and the gasket that goes around cylinders 1 and 4 stuck to the valve cover and we had to pry it out, it was very hard to accomplish. the new gasket once we got the old one off the cover went on smoothly and we used some regular hi-temp sealant from the parts store on all of the curves of where the gasket would fit into.

now the car runs much better on the low end, and the car runs soo much better. I also cleaned off all that oil before putting int he new gasket
 
#22 ·
So you actually saw an improvement in the way she ran after doing the valve cover gasket? I also have an 04 and have a piece of metal duct tape around my intake tube exactly where you have one. That made me laugh. I wondered if that hole was supposed to be there or not...and got to thinking it doesn't matter since it is before the filter. I just changed out my MAF 2 days ago after having a month of poor (weak)running engine issues, and having already done most everything else I could think of, and it helped my low and mid range a lot. It had very little effect on my top end though. I have one plug hole that gets oil every so often but its not bad (doesn't miss)so I've waited on the gasket thing. Now you are making me wonder if the leak at the valve cover is bad enough, could it affect the intake vacuum enough to make her run worse? Hmmm, something to think about.... And my main issue at this point is mileage, and not so much power. Thanks for posting!
 
#23 ·
Kevster, yes that is where the hole is on the other side, it made the engine run better i think that's crazy Kia did that ;0

Yeah, i found out that gasket was stock, and the car has 108,000 on it..it was soo brittle it has been leaking slowly for at least 20,000.. :) it depends on the maintenance history on the car I'd say, but the engine is perfect i literally drove it around yesterday and burned 5 gallons of gas all day and it didnt studder once
 
#24 ·
Changed mine yesterday. The gasket material was hard but not so brittle it wouldn't come off pretty easy. I was able to pull and pry it out and not even break it. The new one (Felpro) ought to seal it up well. I had 139K when I bought my 04 Rio, but I think the previous owners did the maintenance on this car, because it wasn't thrashed under the hood. I have 141K now and it runs good too. Now if I could just figure out how to get it to do 36mpg...
 
#26 ·
Hey dchrsf, Nice pics my gasket looked the same. I had the same issue with oil down in the plugs I think #3 only changed my gasket also but didn't help with power issue but it did solve oil on plugs. I had exhaust issues. After I replaced gasket idle was bad the hose from pcv valve was bad dry rotted and brittle causing vac leak 10 dollars at dealer for new one just one more thing to check. Reguards ronjohn
 
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