[MrGoodman17]

I have a 2000 kia sephia with around 150,000 miles on it. Today when I got in my car to head home, my rpm's started going up and down significantly as if was accelerating from first gear to second. This is the first time I have ever had this issue and I am at an absolute loss as to what the problem could be . Any assistance would be greatly appreciated.

 

[GottaCruise]

Greetings,

Welcome to the forum.

Did the uneven idle occur when you were parked, or when driving?

If driving, what type of transmission is in the vehicle (automatic, 5-speed manual)?

Some additional info. would help us to give some suggestions..

Regards,
GottaCruise

 

[MrGoodman17]

Thanks for the welcome. The fluctuation only happens in park or neutral, but in drive or reverse, the rpm's are so high that I have to hold extra hard on the brakes to keep the car still. The car has an automatic transmission btw.

 

[GottaCruise]

Would start with inspecting the entire air intake assembly, from the airbox -> back to the throttle body, looking for missing hoses, cracks, etc..
and cleaning the IAC valve & Throttle Body intake and plates using Carb Cleaner, and if the MAF hasn't been cleaned recently, cleaning the MAF with (CRC-Brand) MAF cleaner,

and installing a new air filter if older than (6) months / cleaning out any debris from the airbox using a shop vac and/or compressed air..

a general inspection of all vacuum lines / ports from the Intake manifold to respective components might be a good idea also,

In short, I'd start by checking for illegal air, and cleaning/making sure the throttle body/IAC Valve, and airflow is operating as expected,

Lots of posts on how to clean the IAC, Throttle Body, and MAF sensor, but if you have questions, post back, we'll try to help,


Regards,
GottaCruise

 

[MrGoodman17]

Thanks a ton! I'll see what I can do.

 

[MrGoodman17]

Hey guys, I'm finally able to get back on to update you on my findings. I inspected my throttle body to see if I could find any extra air coming from anywhere and I found what I thought to be the culprit, my intake hose had a crack that turned into a hole ($71 replacement from AutoZone by the way). However, after waiting on this hose that had to be special ordered, it turned out not to be the problem. So, I decided to test the IAC by unplugging it while the engine was running, and absolutely nothing happened! Luckily, I didn't have to replace it, I just sprayed it heavily with some STP Intake Cleaner with it still on the engine and drove around the city for about 15-20 miles (40mph average speed) and I felt the idle finally even out. At first it tried to stall a bit but I just gave it a little gas and it went back to normal shortly after. Now I'm running as good as before! Thanks for all the help.

 

[GottaCruise]

Nice job on the diagnostics & fix - congrats on the repair.