Skip the auto shop - Our mechanics make house calls

Q: No power when accelerating

asked by on

I own a 5 speed manual fuel injected Kia Sephia. I bought it used and the check engine light was on. It ran perfectly,so I ignored the warning light. In a few months I felt a very small hiccup off and on when I accelerated. It wasn’t bad, so I let it go. After a month went by it started hesitating very noticeably when I was cruising with the gas pedal held at a steady speed. Then the hesitating got more and more frequent until it turned into bouts of heavy running of loud and slow - then it would run normally again. This happened off and on. I revved up the car to high speeds to keep it running at a normal pace because going slower caused it to hesitate. A few weeks later it did nothing but run loud, heavy and shaky when idling. It almost shut down when I pushed on the gas pedal. Revving it up to high speeds didn’t help it run normally anymore. Up until now when I start the car it runs heavy, shaky, loud and high revving does not good at all. I did replace the exhaust system, spark plugs, fuel filter, fuel pump, fuel pressure regulator, air pressure valve, air idle control. But none of these parts helped. I can no longer drive the Sephia because it has no power when accelerating, and the engine shakes and runs loud. I haven’t replaced the injectors, the injector wire harness, or the coils. Except I did replace the coils and the car still hesitated, so I took them back to the store. When my alternator belt broke I drove the car home. When I put a new alternator belt on all the problems returned. Can you please help me fix my car? Do you have any ideas what this could be? Thank you.

A: Hello! I believe the problem is likely to d...

Hello! I believe the problem is likely to do with the mass air flow sensor. When this sensor is at fault it will be sending a regular error inlet reading which will cause computer to incorrectly apply air fuel ratio.

I recommend that you have the Check Engine Light checked by a qualified mechanic because that will potentially be a huge insight as to why the vehicle is being troublesome.

If the alternator belt keeps breaking you likely have an issue with one of your pulleys. Have a technician check your pulleys to ensure that they spend freely with little to no resistance. If any pulley displays resistance and does not move freely when it turns, then the pulley should be replaced as necessary. Good luck!

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Is there a safe way for pregnant women to use seat belts in the vehicle?

Seat belt design has been dictated by a number of factors over the years, with pregnant women in vehicles being a major factor. Seat belts can be safely worn by a pregnant woman as long as both the shoulder and...

Q: when traveling a long distance my car will not accelerate over 60 my old Nissan did this as well. Is this a known issue?

Hello. Your particular model of Altima is equipped with a CVT transmission that will automatically put itself in a safe mode if the transmission fluid level reaches too high of a temperature. If the fluid temperature climbs too high,...

Q: Where do you find the engine number and transmission number?

Both your car’s engine and transmission have unique identification numbers. While you won’t need this information for title purposes or to insure the car, you might need it for warranty claims or extended warranty work, so it pays to know...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...