Q: transmission problems, fluctuating RPMs

asked by on September 06, 2016

I think my transmission is having problems. What happens is that every time I’m driving my protege 5 it shifts ok. But when I am driving at 60 km an hour or 40 or 100 the rpms seems to go high. But then it goes back to normal. It does this every few minutes, but I’m not sure if it’s a major issue or if something is wrong with the sensor or the possibility that there is some other problem with my car.

Car is hard to shift Inspection $94.99 - $114.99 Get a Quote

Hello. On automatic transmissions, the shift solenoids run by your speed sensors (and other sensors), will allow the RPMs to climb dramatically before a shift. If one or more of these sensors have failed, there is a chance your vehicle’s RPMs will reach higher numbers at unusual times. Your best chance to start diagnosis of the issues will be with a scan tool. Check for proper function and voltage readings from the sensors if possible. If you need help with this diagnosis, a certified mechanic, like one from YourMechanic, can come to your car’s location to inspect the transmission in order to have this corrected.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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


Experienced Mechanic?

Earn up to $70/hr

What others are asking

Car accelerating while in park, shifts slowly.
The most likely issue here would be a faulty idle air control valve. (https://www.yourmechanic.com/services/idle-control-valve-replacement) This can cause the RPMs to rise when the transmission is in park and the engine is just idling. When the engine is not running correctly,...
My actual handle isn't broken. It's Just won't open
The door handle inside a vehicle of your year and model uses a mechanical linkage to transfer the force applied to the handle then to a device that unlatches the door at the jamb. The linkage inside the door may...
Car ran fine. I parked it and this morning it has a misfire in cylinders 1,3,4.
This is a common question. We often want to assign an event like parking our car or filling our fuel tank to a specific failure. More often times than not, this is just a coincidence. My response to such a...
Starter keeps cranking
You have two starter relays. Check and change the starter relay on the inner fender near the battery. Follow the red battery cable to the inner fender relay and this should be your problem. If you are still having trouble,...
Squeaking noise from around the serpentine belt area.
Hello there, many faults will cause your 2009 Ford Flex to have a squeaking noise around the belt area. The most common faults are a failing serpentine belt (https://www.yourmechanic.com/services/serpentine-drive-belt-replacement), belt tensioner (https://www.yourmechanic.com/services/drive-belt-tensioner-replacement), idler pulley (https://www.yourmechanic.com/services/idler-pulley-replacement), alternator (https://www.yourmechanic.com/services/alternator-replacement), or power steering...
My car brakes are spongy
When replacing a master cylinder, it should be "bench bled" before installing it in the vehicle. This involves filling the reservoir with fluid, connecting rubber hoses to the brake line ports and placing the other end in the fluid reservoir,...
CV joint damage
Hello, the CV joints are important components of the vehicle. When the joints fail, they can create vibration and could damage the transmission. Inspecting them should be done at every oil change. Ultimately the CV joint failure will make...
Somewhat over heating. White greyish smoke coming out of exhaust. No heat
Hi there. From the description you have provided, leads me to believe, there may be air trapped in the cooling system. Bleeding the cooling system can be difficult. A cooling system flush (https://www.yourmechanic.com/services/cooling-system-flush) could resolve this issue. The white-greyish smoke...
Car won't start Peugeot 307 Station Wagon
Hi - I suspect the cooling fan has seized or shorted (https://www.yourmechanic.com/article/how-long-does-a-cooling-fan-resistor-last). This is creating enough load to blow the fuse. Disconnect the cooling fan, replace the fuse, and retry starting the engine. Since the engine is starting the first...

Related articles

The Check Engine Light Demystified
Your car Check Engine Light can mean many things. The Check Engine Light comes on when there's an electrical or mechanical problem with your car.
Symptoms of a Bad or Failing Transmission Speed Sensor
Common signs include harsh or improper shifting, cruise control not working, and the Check Engine Light coming on.
How to Determine Compression Ratio
Whether Whether you’re building a new engine and you need the metric, or you’re curious to know how efficient your car uses fuel, you have to be able to calculate the engine’s compression ratio. There are a few equations needed...