Help! My car has lost power while accelerating

Hi, This evening I was driving home after a pint and my car (a 2001 Hyundai Elantra GLS) revved really high for a sec after starting from a traffic light. After that, it took really long for me to get the car up to speed every time I stopped. I would accelerate and the revs would be high but the car would initially move very slowly. I smelled some faint smoke, but nothing overpowering. As we got closer to home we had to go up a really steep hill. We started the hill from a stop and the car didn’t sem like it’d make it up. So, I put it in reverse, went back down the hill, and took the longer way home. I checked the oil levels when I got back and they seemed fine. Does anyone have any suggestions before I get fleeced by a mechanic?

Also, I just had an oil change (about 2 weeks ago, and my drivebelts and sparks in December). THANKS!!!

You did not tell us whether this car has a manual transmission or an automatic transmission, but I am going to assume that it is automatic. As a result, what you described is almost surely transmission-related.

The first step is to check the transmission fluid. My best guess is that you will find either that the fluid level is low or that the fluid is brown and smelly, rather than the normal red, non foul-smelling fluid. Neither scenario is a good one, and either one is potentially going to be expensive.

If the fluid is normal in color and smell, but is at a low level, the first step is to fill (NOT over-fill) the transmission with the correct specification fluid. Instructions for checking the fluid and info on the correct spec fluid can be found in your Owner’s Manual. However, you have to realize that a low fluid level indicates that there is a leak in the transmission. That means that in the short-term, you will need to monitor the level very frequently, and in the long-term, you will need to have the leak fixed, which is potentially costly.

If the fluid is brown and burnt-smelling (which I strongly suspect, given the “faint smoke”), then the situation is much worse, and likely will mean an overhaul of your transmission. This is the situation that results from car owners not changing the transmission fluid every 3 years/30k, as they are supposed to. We don’t know the odometer mileage on your car, but based on its age, the transmission fluid should have been changed 2 or 3 times already. If you have not done this, then you essentially shot yourself in the foot.

In order to NOT get fleeced on transmission work, the first thing to remember is DO NOT go to AAMCO, Lee Myles, Cottman, Mr. Transmission, or any other chain operation, unless you want to be overcharged for sub-par repair work. Seek out an independent transmission shop that has been in business for at least 3 years, and you are more likely to get an honest assessment of what repairs need to be done, and to get a fair price for those repairs, as well as good workmanship.

Now, go out and check that transmission fluid (after reading about the correct procedure in your Owner’s Manual), and then report back to us on the results.

Good luck!

If your car has a manual transmission the clutch is worn out. The smell was the worn clutch slipping.

Dear VDCdriver,

Thanks! Here is the (expansive update):

  1. The car is an automatic.
  2. Transmission fluid: red, with a faint odor. I checked it while the car was idling hot in neutral, as per instructions. It appeared to be at the correct level and color.
  3. I have gotten every service that Hyundai has suggested on schedule, including a replacement of transmission fluid. The car is a 2001 with 65,000 miles.

But, here’s more:

  1. This morning the check engine light was off. The car seemed to work just as it had before this happened. I drove it around some serious hills for about 10 minutes and nothing like last night.
  2. HOWEVER, I had thought my gas tank seemed to be emptying quickly before the event last night. Today, in a 10 minute drive my gas needle said that I had used about 1/10th of the tank. I don’t imagine that this is a good thing.
  3. The ODOR: after I finished driving around today, the car was giving off an odor that I can only describe as smelling like falafel, with a metallic after-taste. It’s the weirdest car odor I’ve ever smelled. I walked around to check that it wasn’t coming from someone’s house and it was definitely coming from the car.
  4. This may help (or not, I don’t know): we moved to NorCal in December from Kansas. We drove the Hyundai cross-country towing a UHaul trailer which must have weighed at least 2,000lbs. We crossed the Rockies, A mountain range in Utah, the Great Basin, and the Sierra Nevadas. In each case we hit snow at the peaks and for hours I had the car in 1st-gear and used 1st-gear and the brakes to stop us sliding down the ranges. I think this drive was pretty rough. We also did it right after the service I mentioned before (all drive belts, shocks, etc… 60K service).

Thanks so much. I look forward to your insight!

Thanks mcparadise. But, the car is an automatic. But, see my response to VDCdriver above for more info.

“This morning the check engine light was off.”

Hmmmm…In your original post, you never mentioned that the CEL was ON!

Even if the CEL is now off, with any luck, there is a stored trouble code or two that can be detected if you have the car’s OBD II system scanned. However, I am not sure if a normal scan tool will detect transmission fault codes on this car. If our resident transmission expert, transman, comes along, he can tell us for sure.

Anyway, I would suggest that you have the system scanned (free-of-charge) by the staff at Autozone, Advance Auto, O’Reilly, or other auto parts retailer in your area, and then come back to this thread to report their findings. The codes should be in the format of P0123.

I would not rule out a slipping transmission and you should try to get the codes av VDC suggests. But I’d also be tempted to look for sticking brakes.

Ok, I just bought an Innova 3100 code reader (CAN OBD2 diagnostic tool). I followed directions. It gave me a green light, said no DTC codes were stored in memory. I tried the procedure several times.

BTW, The great state of California has prohibited Autozone et al. from diagnosing for free. Hence, the need to buy it.

That’s a bummer. However, I had another thought–which happens occasionally, even at my advanced age.

I don’t recall when Hyundai added their 10 year/100k Powertrain Warranty, but if your car has this coverage–and since it sounds like you have done all of the required maintenance–diagnosis and repair should be covered by that warranty.

What is the warranty coverage on your car?

Mt car has the 10 yr/100,000mile warranty on the powertrain. Hyundai says this:

"Covers repair or replacement of powertrain components (i.e. selected Engine and Transmission/Transaxle components), originally manufactured or installed by Hyundai that are defective in material or factory workmanship, under normal use and maintenance. "

Do you think that that will cover what’s wrong?

Could it be on of the sensors that is messing up the fuel/air mixture?


Hmmm…“Selected” engine and transmission components? It sure would be nice for you and for us to know which parts were selected for coverage.

It is much more typical for a Powertrain Warranty to specify exactly which parts are covered, rather than to give that type of cagey statement. I am starting to wonder if Hyundai’s coverage is worth the paper that it is printed on. With vague wording like that, the coverage could vary, depending on the problem. The way that it is worded sounds like what is sometimes referred to in legal circles as a Weasel Clause.

After hearing this distressing information about their warranty, I honestly can’t tell you what would be covered, but if I were you, I would take the car to the dealership in an attempt to obtain coverage under that warranty.


  1. I am going to drive the car around and see if I can get the check engine light to come on again. Then I can have a code and a better idea.

  2. RE WARRANTY: So far Hyundai has replaced rusted control arms and a rusted through part of the muffler for free with little hassle. I just called the Hyundai dealership and he said that if it is a problem with the transmission they’d probably cover it, though we’ll have to wait and see. I’ll keep the thread updated, especially if I get a check engine light to come on and a code.

Offhand, I agree that it sounds like a transmission slippage problem and you should get the car scanned for any transmission codes. Since the transmissions are electronically controlled maybe there was an electrical hiccup causing a fluid pressure loss in the system.

It might not be a bad idea to do a pan drop and see what, if anything, is lying around in the bottom of the tranmission pan. An excess of grunge could be bad news for the transmission.

Unless that pint you speak of was Bacardi 151 and you were in neutral…

(Sorry. Just had to) :slight_smile:

No, the pint(s) were Anchor steam and Cucapa Obscura. I was totally compis mentis. But, I just now drove around for 30 miles trying to recreate the problem. Nothing. I called Hyundai again and a mechanic said it might be a speed sensor. In the mean time, I am going to hold off on going to a mechanic until the check engine light comes back on, at which point I’ll get the code and see what’s up. As soon as I find out I will let all of you guys know. Thanks for all the comments.

Hi All,

It took 90 miles but the check engine light came on again. I plugged in my code reader while the car was still on and got P1529. When the check engine light came on, the car was doing the same thing: revving high in 1st but moving very slowly/weekly. As with last time, the light came on while in very slow traffic. Today, in bumper-to-bumper traffic. My code reader gave some description that said something about a “snapshot.”

I looked around the web but can’t seem to find an authoritative meaning for P1529. Can anyone shed light on the situation?


oh, and when I turned the car off and back on the check engine light disappeared and the car seemed to be acting normally. That may be relevant too.

That code indicates an electronic problem relating to the transmission. One of the transmission’s speed sensors (either input sensor or output sensor) is likely defective. This should be covered by your Powertrain Warranty. Take the car to the Hyundai dealer.

Thanks to everyone’s suggestions. I took it to my mechanic (a Korean specialist) and he ended up changing the input speed sensor (about $200 all inclusive). (I can dig up the second special code that came up if anyone wants it.) Since he fixed it the problem has not returned. He only charged me for 30 mins of diagnostic time as opposed to the two hours he initially thought it might be. I think this is in part because I knew what was wrong already. As it turns out, the check engine light was off when I got there.

BTW, The great state of California has prohibited Autozone et al. from diagnosing for free. Hence, the need to buy it.

Another poor idea from the politicians.

Thanks for the resolution update. Too many people leave us (the responders) just hanging.
The official definition of P1529 is, “Customer Snapshot Request VIA CAN”. Without further definition, the meaning is very obscure. I would guess at something like, “The speed sensor signal isn’t getting sent/received over the multiplexed (CAN) signal wire”.
The other DTC code was probably: P0715 Turbine/Input Shaft Speed Sensor Circuit [has a problem]. The mechanic may have just guessed (from the DTC P0715) at the input speed sensor, and hoped that the problem wasn’t in the rest of the input speed sensor circuit; or, he may have taken the unusual step of testing the signal from the input speed sensor to verify the assumed source of the DTC code P0715. Of course, like the mechanics who use this approach of guessing at faulty parts, he’ll never admit it.
Anyway, by applying your own resources to solving the problem, you saved yourself hundreds of dollars, most likely.

Check the answer at this site: If someone else has the DTC P1529, they can read the TSB (Technical Service Bulletin) 1-40-005 (3/01) and perform the ohm measurements with a multimeter.

From reading the TSB, the speed sensors (and wiring harness) are warranty items. Check with your mechanic about submitting a Warranty Claim. You could recoup all your money (and the mechanic could make some more money from the warranty).