Issues with the transmission while accelerating at low speeds

Hello. There are some transmission issues on my car. The gearbox is automatic. I checked the fluid already as well as the engine oil. The issue starts happening during acceleration at very low speeds of 10 mph on average. It would start revving for a couple of seconds and hesitating as if it is shifting gears. After that, it would gather some speed and accelerate. The engine is 2.4-liter turbo. Do you have any idea what could be causing this? Thanks.
Experienced mechanics share their insights in answering this question :
Hello. It is possible that the first gear in your transmission is slipping. There could be other transmission parts that are slipping as well. Additionally, the car’s turbo or turbo components could be faulty. Have a certified technician, like one from YourMechanic, come and inspect your transmission and turbo system in order to pinpoint the source of your problem.

How to Identify and Fix Common car Problems ?

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

Automatic transmission problems can be caused by a lack of transmission fluid. If you are experiencing slipping, the first thing you should do is check your transmission fluid levels. If they are low, you should top it up and check for leaks. Slipping can also be caused by burned or worn out fluid.
In an automatic transmission, slipping can be caused by wear and tear on numerous different parts. These include damaged or worn clutch plates, transmission bands, and solenoid packs. If your automatic transmission has been slipping, it`s likely a technician will replace some or all of these parts to fix the problem.
What is the fix for a slipping transmission? It`s simple. Just pop the hood of your vehicle, locate the transmission switch, and change the setting from “SLIP” to “STABLE” . . . If only it were that easy.
The Transmission Range Sensor tells the PCM the position of the transmission shifter. The PCM uses this information to control which gears of the transmission to enable or disable. When the TR sensor fails it can cause wrong gear starts, no upshifts, or what feels like a falling-out-of-gear condition.
Transmission Slipping

Transmission slipping is quite common, and can be caused by a variety of transmission issues such as low fluid levels, fluid leaks, worn out gears, or solenoid problems.

When your manual transmission slips, 99 percent of the time, it is due to a worn-out clutch. Over extensive use, the clutch will wear thin and won`t be able to run as required. Ideally, your clutch needs to run anywhere from 20,000 to 200,000 miles before replacement.
One of the easiest ways to fix and prevent a slipping transmission is to monitor the transmission fluid level. Once a month, open the hood and check the fluid level with the engine running. If low, top it off with the recommended transmission fluid mentioned in the owner`s manual.
To put it briefly, no you should never drive your vehicle if you believe there to be an issue with your transmission in any case. Once a transmission starts slipping it needs to immediately be repaired. Every time you drive it after you feel your transmission slip, it is a risk.
Typically with transmission slipping, it may feel as if your gears are changing for no logical reason. Your engine may start to create a whining sound or pitch when it occurs. Alternatively, it may feel like you haven`t got enough power to drive at the desired speed.
Slipping

A malfunctioning torque converter can have a shudder that comes from the transmission. The slipping occurs while you`re driving or changing gears, and it usually comes with some odd noises too. Remember, a torque converter is a coupler between the engine and transmission.

Common signs include harsh or improper shifting, cruise control not working, and the Check Engine Light coming on.
Car operating in incorrect gear – The most common symptom of a failing transmission range sensor is difficulty shifting gears. If the sensor is malfunctioning, it may not be able to correctly identify the gear position of the transmission, leading to difficulty shifting or even transmission slipping.
A damaged fin or bearing in the torque converter can cause hesitation in the transmission shifting, or the transmission to slip out of gear entirely. This is because the engine torque is not being efficiently converted into the hydraulic pressure needed to shift gears within the transmission.
When you accidentally use the wrong transmission fluid, there are a few common signs that your transmission will throw off indicating wrong fluid: The car will stall while shifting gears. Your engine will produce a clunking sound. The gears will begin to slip.
If a transmission has too much dirt or sludge in the fluid it can cause a sluggish response when shifting gears. It may be time to flush the transmission fluid in an automatic if the car changes gears too quickly or too late.
If your car is slipping between gears without any input, it`s dangerous for you and damaging for your engine. Low fluids and worn transmission bands can cause gear slipping.
Achieving a true 1:1 speed relationship between the turbine and the impeller is not possible with a non-lockup torque converter since it is still a fluid coupling. Most street torque converters tend to operate in the 3 to 5 percent slippage range, but this can go as high as 8 percent.
A damaged torque converter will be unable to provide a seamless transfer of the engine`s rotational force into hydraulic pressure. The downside to this is that there could be an increase in the normal stall speed, and as such, it could take the transmission more time to engage the engine.
With the engine warmed up, leave the car idling in park on a level surface. Pull out the dipstick, wipe it clean, replace it slowly, and then pull it back out. Check the fluid level—how high the fluid comes up on the dipstick—against the “full” and “low” or “fill” marks on the dipstick.
A car has two speed sensors: the ISS and the OSS, working together to show the transmission data to the car`s powertrain module. The ISS sensor monitors the input shaft`s speed. If these sensors get misaligned, the operation of the transmission system will be affected.
Occasionally, these sensors can fail or become faulty working intermittently sending inaccurate signals to the ECU. In your case it may be possible that the transmission is receiving a faulty signal from the ABS system.
Note: The transmission speed sensor is located in the rear of a longitudinal mount transmission. For transaxles, the speed sensor is located on the long side of the output shaft. This would be the end of the transaxle that faces the front of the engine.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Issues with the transmission while accelerating at low speeds
ANSWER : Hello. It is possible that the first gear in your transmission is slipping. There could be other transmission parts that are slipping as well. Additionally, the car’s turbo or turbo components could be faulty. Have a certified technician, like one from YourMechanic, come and inspect your transmission and turbo system in order to pinpoint the source of your problem.

Sluggish acceleration during quick speed increase
ANSWER : The intake variable runner control may be stuck in the wrong position and would need to be checked to see if it is able to move. The control valve for this or the solenoid for the variable valve timing may be stuck or have open circuit. Have systems tested for operation and scanned. I’d recommend getting some help from a professional mechanic who can diagnose your acceleration issue. Once this is done, an accurate repair can be followed through.

Automatic transmission issues, high RPM at low speeds
ANSWER : Hello, thanks for writing in about your 2000 Chrysler Cirrus. The transmission control module would need to be scanned to see if the codes stored may indicate the shifting problem you are having. You may have an internal shift solenoid problem causing the shift problem. A speed sensor for the transmission may also cause the transmission not to go past second gear. I recommend having a qualified technician, such as one from YourMechanic, inspect your shifting issue and high RPM problem in person in order to have the correct repairs made.

Car jerks when accelerating in reverse & makes grinding noise. Is this a transmission or computer issue?
ANSWER : Hi there. Typically when you hear a grinding noise when you move forward or in reverse it’s usually an indication of a gear fault either in the transmission or another driveline component. If this occurs only when in reverse, it’s likely a damaged reverse gear. It is also possible that it’s a hydraulic fluid issue not supplying enough lubrication or pressure inside the lines to fully open the gear. I would recommend having a professional mechanic come to your location and complete a car is hard to shift inspection, so they can diagnose the source of your issue and recommend repairs that should resolve this problem.

Bad instant acceleration on high speeds. Works just fine on low end speeds 0-60.
ANSWER : Hi there. It is possible, the fuel pump and/or fuel filter is responsible for the lack of power at freeway speeds. It could also be, the exhaust system is restricted ie; restricted/plugged catalytic converter. The lack of acceleration at low speed and high speed may be a faulty MAP (manifold absolute pressure) sensor incorrectly calculating engine vacuum. There are more possibilities and proper diagnoses should be performed. Replacing components without diagnoses, can be expensive and time consuming without resolution. I recommend having your vehicle’s slow to accelerate at 70mph be diagnosed and repaired by a certified technician, such as one from YourMechanic.

2013 Ford Focus Transmission Issue. Is it worth keeping the car?
ANSWER : Hi There,
This is a known issue in this generation Ford Focus and some Fiestas with the "Power Shift" transmission and there have been numerous recalls and lawsuits. Although, it is would be difficult to determine how much longer your transmission will last given the fact that you have many new parts, I would not recommend junking the car as it may still provide some valuable life left for you. I would recommend taking it to the dealer to see if these parts may be covered under the recall.

Problem with speed. No check engine light on but when accelerating speed, it decreases then speeds right back up. No stalling at all
ANSWER : Hi, thanks for writing in. This is a common problem associated with fuel/air delivery which is very commonly related to what is called a mass airflow sensor. This monitors the flow of air intake into the throttle body as it is mixed with fuel to deliver the right air/fuel mixture into the motor. When this is not working properly, this will cause this kind of hesitation or surging when trying to accelerate. I would recommend having an expert from YourMechanic come to your home or office to confirm a diagnosis on the issue and make or suggest the necessary repairs or replacements.

Car making a low noticeable sound at speeds between 55 km/hr to 70km/hr.
ANSWER : Hi there:

Diagnosing ’noises’ remotely is one of the more difficult things to do for any mechanic. However, there are a few things which could cause this noise, ranging from loose motor mounts, loose serpentine or drive belt, pulley’s or even wheel or front end suspension issues. The best way to diagnose any problem is to have a professional mobile mechanic complete a car is making a noise inspection; so they can ride with you to attempt and replicate the noise; which will help them pinpoint the source of the noise and recommend the right repairs be completed.