Q: There is a couple hiccups in acceleration ONLY on FIRST start up and ONLY when put into reverse before drive. 2004 Hyundai santafe

asked by on

There is a couple of hiccups in acceleration ONLY on FIRST start up and ONLY when put into reverse before drive. It happens every time without fail. It will not do it for the remainder of the drive. It is extremely noticeable. I did just drain and fill the automatic transmission fluid with authentic Hyundai AT fluid. But level is good. Thank you for your time.

My car has 73000 miles.
My car has an automatic transmission.

This may be a sign of a faulty MAP sensor as the vehicle responds adversely to a load put on the motor (i.e. putting it in gear, making turns (which makes use of the power steering pressure switch) turning on AC or engaging the brakes). The Manifold Absolute Pressure (MAP) sensor senses engine load and generates a signal that is proportional to the amount of vacuum in the intake manifold. The engine computer then uses this information to adjust ignition timing and fuel enrichment. When the engine is working hard, intake vacuum drops as the throttle opens wide. The engine takes in more air, which requires more fuel to keep the air/fuel ratio in balance. When the computer reads a heavy load signal from the MAP sensor, it adjusts the fuel mixture to slightly more rich than normal so the engine can produce more power. The computer will then retard (back off) ignition timing slightly to prevent detonation that can damage the engine and decrease performance. This may also be caused by other closely related components such as a dirty or failing mass air-flow sensor, a faulty throttle position sensor or potentially a vacuum leak. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. There is a couple hiccups in acceleration ONLY on FIRST start up and ONLY when put into reverse before drive. 2004 Hyundai santafe

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Q: Radiator leak

Hello there! To verify if the radiator is in fact leaking, I would recommend that a well-trained technician performs a pressure test on the cooling system. Pressure testing the system will expose any coolant leaks in the system and make...

Q: Changed fuel tanks, getting P0183 OBD code now.

Hello, thanks for writing in. Code P0183 is the code for a fuel temperature sensor A circuit, high input. This code is set off when the computer detects that the sensor is out of range. In the particular instance the...

Q: A/C Blowing HOT air. 2001 Hyundai Santa Fe

Hello. If there is no pressure in the system, then that means that there is a leak in the system. If there was no refrigerant, then there is going to be air in the system. If that is the case,...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
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...