2000 Hyndai Sonata V6 Sluggish Acc. High RPMs

[Michale]

My daughter just got a new car. An 2000 Hyundai Sonata 6cyl, Automatic.

In the last few weeks a sporadic problem has developed. It'll be driving along at 75 or so on Cruise Control. All of the sudden, the car will buck and the acceleration goes way down and the RPMs shoot way up. This happened at lower speeds as well. It would accelerate real slow and sluggish (but not spurting or stuttering) and the RPMs would be way high, in the 4-5K range. Check engine light would come on.

But it hasn't done this in a week or so. Everything appears to be OK. Check engine light is off and it accelerates normally.

All fluid levels appear to be normal.

Anyone have a clue??

Thanx

Michale

[MXlonerider]

Only with cruise on? From the sound of it, and just a general experience, I'd say it may very well be the catalytic converter clogging up.

[Michale]

Originally Posted by MXlonerider

Only with cruise on? From the sound of it, and just a general experience, I'd say it may very well be the catalytic converter clogging up.

It's happened three times. Twice while on cruise and once when not.

Catalytic Converter.. Hmmmmm Had not considered that.

Any way to confirm? Other than replacing it and see...

Thanx for the response.

Michale

[Slow_n_ez]

Last year our Jimmy was doing same thing .............

If you punch it ( floor it ) does it just bog down with high rpms ?

Is there a sound like a rattle when you first start it ?

Does it lose speed when trying to climb a hill ?

My Jimmy would not climb a hill without having to floor it and go up in second gear with rpms like around 4000 ..... Of course beads of sweat formed on my fore head thinking any moment the engine is going to blow ..... As soon as I got back from short trip I took it to a muffle shop and had a new catalytic converter welded on and problem was instantly fixed ...

As MXlonerider says . its clogging up ... gradually it'll get worse .... When one gets clogged up the exhaust doesn't have where to go .......

If you want to " try " to see if that what the problem really is or not .... go to auto parts store .. get a muffler clamp or better yet a exhaust pipe adaptor ... cut the exhaust pipe someplace in front of the converter ( towards engine ) .... make sure your clamps are easy to install in the area you cut .... pull the muffer pipe away so it'll have free flow of exhuast and secure it ...... Take it out and drive ( I wouldn't susgest very far ) .... of course it'll be very loud as its just straight pipe off the engine block .... If you get nice smooth acceleration and the problem has gone away ... you need the new converter .... if not.. then you need to use the clamps you bought before starting this ......

[MXlonerider]

A lot of times you'll hear the cat rattling. While in neutral, see if you can hear it, or even while not running jiggle the pipe and listen, you may be able to hear it. It wouldn't be a contant problem as it's not technically clogging up, just the peices inside are jiggled into position blocking most of the output when there is a lot of flow, such as when you're accelerating or cruising at higher speeds. Other than that, you can take it to a muffler shop and have them just take a look inside, not replace it, if it wasn't that, all they'd charge would be labor to cut the cat off and then weld it back on. Or, if that did turn out to be the problem, they could go ahead and replace it while they had the car there and you'd be all fixed up.

[Michale]

Thanx to everyone for their responses.

I have what may appear to be a really stupid question.

Is it possible that this condition might be caused by low gas??

The reason I ask is this.

It happened today again with my daughter driving. She was cruising along about 65 or so and then it bucked, got a little sluggish and the CHECK ENGINE light came on.

I took it around for a test drive and noticed that the gas gauge was almost to the E mark. So, I thought to myself, "hmmmmmm"...

I put gas in it and the CHECK ENGINE Light went out.

So, I am guessing here, that the CHECK ENGINE light doubles as a LOW FUEL indicator and the BUCKing and sluggishness could be caused by either air being sucked in or sediment being sucked in, in a low gas tank situation.

Does this sound reasonable?


Michale

[MXlonerider]

Definitely reasonable. I dont know where the pump is in these tanks, never had to lower mine and look in it, but this could be especially reasonable when either going up or down inclines.

[jmcb]

I know this is an old post but I'm having the same problem with my 2000 sonata and it just did it again the other day. I had a full tank of gas and I was driving on a flat road.

[saintsfann76]

sounds like it may be vehicle speed sensor, if the engine light came on., my optima did the same thing almost, you know a kia and sonata are one in the same