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RPM rev and no acceleration?

I have a 2004 Hyundai Sonata with about 85,000 miles. For the past few weeks, when trying to accelerate, I press down steady on the gas pedal, and sometimes the car does not accelerate. Also, the RPMs rev very high from about 2 to sometimes 5,000 (all with no acceleration). This seems to happen randomly, regardless of how fast I am driving or the road conditions. Today, the check engine light came on as well when it was happening. Any ideas? Thanks!

Check the transmission fluid. How does it smell, burned or like good oil? Is it brown or red? Get the trouble codes that triggered the CEL read. Get the raw codes and post them here.

This is almost surely a transmission problem. As B & B suggests, the first step is to check the level, color, and smell of the fluid.

If the fluid level is low and adding fluid does not immediately remedy the problem, I suggest that you limit the amount of driving that you do and that you get it to an independent trans shop a.s.a.p. The more driving that you do, the greater likelihood that you will completely wear away the friction surfaces in the transmission.

Whatever you do, DO NOT take it to a chain operation like AAMCO, Lee Myles, Cottman, Mr. Transmission, etc. These places are reknowned for poor quality, overpriced work and for failure to stand behind their work after the transmission fails again.

Certainly get the codes.

But I agree that it is likely the transmission. Be prepared for the worst.

Did anyone say this was an automatic? Did I miss something? If it is a manual, the clutch is probably slipping.

Well, either way its probably slipping clutches isn’t it? I’d be surprised if anyone has a Sonata with a manual.

A slipping clutch on a manual is not a transmission problem tho. I would not be surprised if a Sonata had a manual. If it is automatic, I’ll shut up!!

"I’d be surprised if anyone has a Sonata with a manual."
I looked up the Sonata on internet and the base model has a choice of a manual transmissiion.
I would like to know if this car has a manual or automatic.

Let it go already. This looks like one of those OP’s who post a question, perhaps hoping for some kind of “oh, just replace this $.15 fuse” answer, find out they have a mess and never bother to come back. It happens all the time, of course. The other kind that never comes back are probably those who can’t navigate their way back to the site and/or their post.

And if we were in a bar I’d lay a wager on an automatic.

OP here. It is an automatic. I checked the trans fluid level and it was a bit low, so I put in a quart and will check the level again today. The fluid on the stick when I checked it was brown. The CEL went off, actually before I checked the fluid level, but now it’s back on again. We have horrible weather here right now that is pretty much a white-out (northwest Indiana), so everyone is staying home. Once the weather and roads clear a bit, I’m taking it in. How would I have the CEL code read without taking it in though?

Parts stores will often read the fault codes that tripped the CEL, but since you’re taking it to a shop to be fixed, don’t bother having the check engine light codes read. The tech will do that at hisi own shop as part of his diagnosis even if you have them in hand from some other source. Tell the shop all of your symptoms and let them apply their expertise to the problem.

Probably over half of the people who ask questions here are doing their own work amd asking here for advice and guidance. When the CEL light is lit (and often when it isn’t) we usually ask them to get the fault codes read and post them in order to help us start out in the right direction, just as the tech at your shop will read your codes to help him in his diagnosis.

“The fluid on the stick when I checked it was brown”

That is not encouraging, unfortunately. I have to conclude that the fluid was not changed recently, or more likely, has never been changed.

Good practice (whether recommended by the car manufacturer or not) is to change transmission fluid every 3 yrs/30k miles, whichever comes first. When this is not done, additives in the fluid become depleted and damage can occur. Additionally, debris from the normal wearing of the friction surfaces remains in the transmission, and this causes problems including clogging of the tiny passages that the fluid has to pass through.

When trans fluid is not changed as per the above schedule, transmission failure can take place any time after ~90k miles, and is almost a sure thing by ~120k miles. Hopefully you will be able to dodge a bullet this time, but I urge you to use the maintenance schedule mentioned above to prevent future problems with this car and with cars to follow.

Good luck!

What about the fuel filter? Couldnt a dirty/clogged fuel filter be restricting the amount of fuel getting to the engine when accelerating and causing these problems?

“Couldnt a dirty/clogged fuel filter be restricting the amount of fuel getting to the engine when accelerating and causing these problems?”

More than likely, the OP–who posted his problem situation 9 years ago–got rid of his car long ago. But, to answer your question…
No, a clogged fuel filter would not explain an engine that is revving at high RPMs without the car moving at an appropriate speed. The most likely explanation would be a failing transmission if it is of the automatic variety, or a slipping clutch if it has a manual transmission.

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