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.

A: If the split seal on the air intake is afte...

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.

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: Slave cylinder popping out

I would recommend having your hydraulic clutch system inspected by a technician who is proficient in transmission repair. If your slave cylinder is leaking, you could end up getting stranded somewhere due to not being able to shift gears. If...

Q: how to change 4 shock absorbers ?

This vehicle has front and rear struts on most models and can only be done using specialized equipment to compress the spring to get the strut apart. The vehicle would then need to be aligned. If you need some help...

Q: Rear lights not working.

Looking at the wiring diagram for your vehicle, I see that none of these circuits share a common ground. They do however, all receive power from the totally integrated control module (TIPM). This module is basically a smart fuse box....

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...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
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...