Can’t accelerate above 35 mph

Can rear motor mount on van keep it from going over 35 mph before it starts vibrating real bad?

My car has 160000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Hi. The rear engine mount shouldn’t keep the van from going over 35 mph. Unless it has broken and it caused damaged to the axles or the transmission. It sounds like there is an issue with your transmission not shifting properly causing this problem. There also could be a problem with the catalytic convertor being clogged not allowing the proper exhaust flow. This will cause the engine to choke and not go over a certain speed. If you would like to get a precise diagnosis, a certified professional from YourMechanic can come to your car’s location to inspect the acceleration problem and follow through with repairs.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

Most of the time this is triggered due to a problem within the transmission. Either minor like low or leaking transmission fluid, a loose or malfunctioning sensor or a major component problem.
One of the most common reasons for poor acceleration is a problem with your car`s air intake system. If there is something blocking the air flow into your engine, it will prevent your car from getting the oxygen it needs to create the combustion needed for acceleration.
An engine that is hesitating to accelerate is most likely dealing with a fuel/air mixture that is too lean. Engine`s that are running inefficiently will begin to show signs like hesitation which will only become worse over time.
“Limp Mode” – If your car won`t accelerate over 25 or 40 mph, it could have engaged `limp mode. ` It is also known as a limp home mode, and it acts as a preservation feature. It is meant to get you home, to an auto mechanic, or safely off the road without destroying your engine.
If you can continue to increase engine speed once you reach 45 MPH but the vehicle won`t actually go faster than 45 MPH, there could be a hydraulic fault in the transmission, a low transmission fluid level, slipping bands or clutches, a torque converter defect and so forth.
An engine that is hesitating to accelerate is most likely dealing with a fuel/air mixture that is too lean. Engine`s that are running inefficiently will begin to show signs like hesitation which will only become worse over time.
It sounds like your transmission is slipping. It does not mean it needs replaced. You will need to have the transmission checked and fixed for leaks and refill transmission fluid, then see if it still slips. Have a transmission mechanic diagnose the transmission for you.
When you press down the accelerator pedal and get minimal output, it could mean you have a problem with your fuel system. The most probable issue is a clogged fuel filter. Your fuel filter works to ensure that dirt and debris do not get into the fuel system.
If your car is not accelerating, the first thing to check is the air filter. The air provided to the engine for the combustion process passes through an air filter, which catches all the impurities and debris present in the air. With continuous usage, the air filter gets clogged and doesn`t let air pass through it.
Worn Transmission Fluid (Automatic Transmission)

Over time, the transmission fluid gathers dirt and grime. This can cause the engine to run roughly, stall or fail to accelerate when you press down on the gas pedal. You may need to have a transmission fluid change before more damage is done.

If your vehicle is having trouble going past 40 mph, then check the mass air flow sensor (MAF) and the fuel pressure regular. Both of these items could be restricting the engine and causing it to have a loss of power.
This is a sign of a potentially failing or dirty mass air flow sensor. This is a unit that regulates the air intake into your engine and ensures that proper air/fuel mix is injected into the engine.
Throttle Body Issues: A dirty or malfunctioning throttle body can cause the engine to struggle to draw in air, resulting in a lack of power and slow acceleration. Low air pressure in tires: Low air pressure can increase rolling resistance and decrease the car`s performance, leading to slow acceleration.
Yes. While the damage may seem small initially, the longer you drive with a bad oxygen sensor, the worse the damage will become. Eventually, you may experience rough idling, poor acceleration, engine misfires, an illuminated check engine light, and failed emission tests.
Common causes of why a car feels sluggish when accelerating include dirty mass air flow sensor (MAF), faulty spark plugs, defective throttle position sensor, clogged catalytic converter, faulty oxygen sensor, clogged air filter, and fuel system malfunctioning.
It sounds like your transmission is slipping. It does not mean it needs replaced. You will need to have the transmission checked and fixed for leaks and refill transmission fluid, then see if it still slips. Have a transmission mechanic diagnose the transmission for you.
Many different faults can cause the vehicle to jerk and have acceleration issue. The most likely cause of these are spark plugs, battery, alternator, fuel pump, low transmission fluid, MAF sensor, vacuum leak, exhaust leak or oxygen sensor. All of these would need to be ruled out before the transmission was replaced.
When you press down the accelerator pedal and get minimal output, it could mean you have a problem with your fuel system. The most probable issue is a clogged fuel filter. Your fuel filter works to ensure that dirt and debris do not get into the fuel system.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

My car is hesitating / jerking at speed intervals of 20 mph, 30 mph, 35 mph and 40 mph.
ANSWER : This may be a sign of a dirty or failing mass air flow sensor. The mass air flow sensor is a unit in the intake system that monitors air intake as it is mixed with fuel prior to being injected into the motor. When this fails, this can cause an imbalanced air/fuel load to be supplied to the motor which results in an over fueling or under fueling situation depending on the conditions. This may cause a hesitation, loss of power or jerking reaction when this sensor is malfunctioning. When this is not working properly, you may also notice a strong smell of fuel. I would suggest having a professional from Your Mechanic come to your home to diagnose your mass air flow sensor.

No acceleration past 30 mph, then 10 mph
ANSWER : Hello there, thank you for asking about your 1999 Chrysler Intrepid. The engine oil being overfull will not turn on the Check Engine Light. However, a transmission problem could and that’s what your issue sounds like. The first step in diagnosing your vehicle is to retrieve the diagnostic trouble codes (DTCs) associated with the Check Engine Light. These codes serve as a starting point for any further diagnostics. You’ll also want to check the transmission fluid level to see if it is full and clean. Often an internal transmission problem will result in fluid that is contaminated with metal, friction material, and/or smells burnt. My best advice is to have your vehicle inspected by a professional from YourMechanic who can replace/refill the transmission fluid if needed.

ok my 99 tahoe truck would drive over 35 mph got the problem fixd. no its a little over 10 months later and its doing it again but
ANSWER : It’s possible you have an exhaust restriction due to a plugged catalytic converter. To check that you could either measure exhaust back pressure and/or intake vacuum (latter gives only indirect indication of a restriction though). Among the other common possibilities for loss of power are throttle body faults (electronic throttle controls, mass airflow sensor, torn air intake hose), worn out spark plugs, faulty fuel pump or restricted fuel system, and large vacuum leaks (including EGR malfunctions, PCV system, leaking intake manifold, leaking EVAP purge valve). A scan tool would be used to look at real time conditions within the engine (particularly fuel trim, etc.) and identify the root cause. If you want these diagnostic tests performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a loss of power inspection/diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

The car shudders between the speeds of 25 mph to 45 mph when accelerating. What is the problem?
ANSWER : Hi there. Check the engine and transmission mounts on your vehicle. When accelerating quickly, the engine and transmission move around causing the loose or broken mounts to make the engine and transmission move around violently making the front tires to jerk side to side. This will make the vehicle shutter at low speeds and continue until the throttle is matched with the road speed. If you need further assistance with your vehicle shuttering at low speeds, then seek out a professional, such as one from Your Mechanic, to help you.

Car accelerates very slow when it hits 20 mph and neutral shift on dash starts to blink.
ANSWER : Either the transmission has thrust bearings or bushings that are worn causing the internal parts to go out of balance or there is an issue with the fluid is low causing the gears to slip. If the fluid is full and new, then the clutches may be worn causing them to slip. I recommend seeking out a professional, such as one from Your Mechanic, to help you diagnose your transmission shaking issue.

Car runs fine at first then will not accelerate past 20 mph on a 2003 Kia Rio
ANSWER : Hi there. The problem with the auto part store scanning is they do not complete the inspection to pinpoint the precise source of the issue. For example, if an error code might indicate an issue with the speed sensor, it’s not always the sensor that is the issue. In fact, in most cases, it’s the electrical harness or just the connection of the sensor to the harness that is the problem. Your best option to correctly have this diagnosed is to have a professional mobile mechanic complete a car is slow to accelerate inspection at your location.

Won’t accelerate pass 35 mph.
ANSWER : This may be a sign of a clogged catalytic converter. The catalytic converter converts toxic exhaust gases into less harmful pollutants that are suitable to be expelled into the atmosphere. When this is clogged, this causes these gases to be backed up into the exhaust system not allowing the engine to breathe properly. When this happens, the engine is forced to work much harder to expel these gases. This often results in the engine bogging down, hesitating, shaking and causing very poor fuel economy. This should also cause a check engine light to come on as the O2 sensors should be reading the incorrect amounts of oxygen in the exhaust gases if this is your problem. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your catalytic converter.

Hi My Toyota Prius starts shaking on acceleration
ANSWER : HI there. Usually cleaning the MAF sensor is done with an aerosol cleaner like brake cleaner or carburetor cleaner. These have alcohols, so cleaning the sensor the way you did should not have an impact. In most cases, the type of vibration you are describing is caused by loose motor mounts, or perhaps a tire / wheel that is out of balance. The best way to diagnose a problem like this is to have a professional mechanic complete a test drive and a car is shaking or vibrating inspection so they can pinpoint the source of this problem.