Skip the auto shop - Our mechanics make house calls

Q: Hard throttle bucking

asked by on

only just bought car ,intermitant fault ,after full service noticed this fault ,split seal on air intake ,replaced ,code stored that keeps apearing ,o2 sensor open circuit ,and exhaust back pressure ,the o2 code clears which leads me to think its not wiring but breaking down internaly ,could this cause surge or kangarooing effect _heavy throttle .car runs well most of the time ,but using more fuel .

My car has 134000 miles.
My car has an automatic transmission.

If the split seal on the air intake is after the MAF (Mass Airflow Sensor), it will cause this problem. When you give the motor a lot of throttle, a much larger amount begins to flow into the motor. This rush of air makes the split in the air intake larger pulling in what is known as unmetered air. This means the motor is getting air that the PCM (Powertrain Control Module) does not see entering the motor. The result of this is an incorrect air fuel ratio. Your O2 sensor will detect a problem with the air fuel ratio and set a code.

Following "split seal on air intake", it says replaced. If the air intake has been replaced and these codes are still present, I would turn my attention to the exhaust back pressure code. This would indicate a clogged exhaust. This is fairly easy to check for. Simply attempt to rev the motor in neutral. Floor the gas pedal and see if the motor will quickly move to red line. I know this sounds like a bad thing to do, but I assure you, this is actually a normal test procedure. If it reaches the red line quickly, let off the throttle. If the exhaust is indeed plugged, the RPM (revolutions per minute) will climb slowly and may not actually reach the red line.

Another test is to put your hand in front of the exhaust pipe and see if there is a steady and firm pressure exiting the exhaust pipe. If it is really soft and won’t move your hand, you have a plugged exhaust. To further test this, you can have someone rev the motor while your hand is in front of the exhaust pipe. The pressure should become very strong. If it doesn’t, increase dramatically, you have a plugged exhaust. This is almost always because of a collapsed catalytic converter. A plugged exhaust can create the surging as the catalytic converter can expand and contract varying the amount of air that is allows to pass through the system. Different driving conditions can change this greatly.

Your O2 can have an intermittent open in the O2 circuit. This can happen internally in the O2 or externally in another part of the circuit. It should be noted, if the exhaust is plugged, it can create symptoms such as this.

If you should need further assistance, consider YourMechanic, as one of our mobile technicians can come to you and diagnose the throttle bucking you’re experiencing and help you fix it accordingly.

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!
  1. Home
  2. Questions
  3. Hard throttle bucking

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: my serpintine belt snaped, i noticed the power steering pulley was bent i re placed it but am not sure if the pulley should spin

If there is no drive belt on the pulley that is on the power steering pump, you should be able to turn the power steering pump pulley freely and easily by hand. If the pulley (shaft) does not turn, that...

Q: Car hesitating when accelerating.

There are many sensors on a car that the computer relies to tell it what is happening. Things like engine temperature, air density, elevation above sea level, ambient temperature, etc., are all readings that your cars computer uses to determine...

Q: Car is not starting, recently changed the battery, i am able to turn on radio also.

Hello There, This may be a result of the weak battery or potentially a faulty starter relay. If there is sufficient power to turn on the accessories (i.e. radio, etc.), but not enough to turn the motor over to start,...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.