I have a 2001 Santa Fe, 2wd. The problem is when it downshifts on its own to provide more power ( its in 4th gear and needs to go faster to get up to speed, it jumps down into 3rd) When it does this, it bucks the car while doing so. My wife says it feels like its slipping. It doesnt doing it when shifting into a higher gear, only into a lower one when more power is needed. Sometimes it will happen if I slow down very quickly, but that doesnt happen very often. I know its only on the downshift b/c my car lets me take control of the shifting if I want to, and when I keep it in a lower gear until its ready to go higher, it never jumps, but when it needs to go lower, it jumps. I dont do this often, and hardly EVER before this problem started, so I really doubt it would hav been from me incorrectly shifting b/c I only did it a handful of times and a good while before it started. I have checked the fluid level and it is good.

 

How many miles do you have?

When was the last transmission flush?

Did you do the transmission flushes on time?

Is there a "check engine" light?

 

144,000 miles

I havent done one since I got it in August 2007 with 82,000 miles

no, I dont, I didnt know I needed to do them

yes, but i am getting p0421, which Im told isnt related to this problem.

Thanks for the reply!!

 

Probably if you had read the owners manual, the specified interval for transmission flush is 30,000 miles. You can't just take it to Jiffy lube for this because Hyundai cars are rather finicky about what fluid you put in them, only use Hyundai spec fluid in a Hyundai transmission. So take it to the dealer for a flush, and expect to pay $200 for a good job. It might not fix your problem, but it's long overdue.

P0421:

Probably your "downstream" oxygen sensor needs to be replaced, or your exhaust flex pipe is leaking. If you haven't changed the spark plugs, you should do that. All these things can be considered normal wear and tear.

 

I got the tranny flushed, and am still having this problem. It doesnt jump as bad, but its still jumping when it downshifts to give more power. Any ideas?

 

When was the last tune up?
When did you last change the timing belt?
Did you get the PO421 code fixed?
Fuel filter changed?
Air filter?
Reset the adaptive learning?

 

tune up- Last September
Timing Belt- 60,000 miles ago
P0421 fixed- No, not yet.
Fuel Filter Changed- No idea
Air Filter- Last August, I think. Have vacuumed it out since
What is Adaptive learning? Is it easy to do?

 

It seems to me you're not too "up" on the maintainence.

"Tune up" usually means they just change the plugs. It's usually a total rip-off unless there's one actually misfiring.

Timing belt gets changed at 60K. Probably yours is stretched out, doing weird things to the timing, could be making the transmission do strange things too. Don't get lazy on this one, as if it breaks it will destroy the motor.

P0421 - You need to fix that.

Fuel filter - Since you've been driving the car for 60K and you didn't change it, then assume it's not good.

Air filter - Every 20K

Adaptive learning - These transmissions do a "adaptive learning" thing. They set the gear changes based on your driving habits. Wouldn't hurt to reset it. You can do it by removing the negative battery cable for 15 minutes, but this will also clear the P0421 code too. See if the P0421 code comes back.

Any of the above problems could cause your car to run and drive "funny". No telling what the problem REALLY is. Good chance it could clear up with better car care.

Take better care of your car, and it will take better care of you.

 

I had no idea that all needed to be done regularly, I thought if it aint broke dont fix it. I will look in my manual for the routine maintenence and will try to keep up with it as money premits. Thanks for the help, I will let you know when I get thse done and how it works out. I am resetting the adaptive learning right now.

Thanks!

 

Hey!!! Resetting the adaptive learning worked!!! Thanks so much!!!!