Top 4 Reasons a Tachometer is Important to a Car's Performance

The modern car, truck, and SUV has become more dependent on technology every year. From driver-assisted safety systems to advanced fuel system monitoring and adjustment software, today’s daily driver is a far cry from those of the past. One holdover (typically on manually-shifted vehicles) is the tachometer. In years past the ‘tach’ was used by a driver to determine the best and most efficient time to shift from a lower to a higher gear. Today’s visual tachometer is not as vital as in years past, but it does serve a purpose.

Understanding the Actual Purpose of the Tachometer

Contrary to popular belief, the tachometer is more than a simple gauge that display’s engine speed. The tachometer is actually comprised of a system of monitoring equipment that captures data, relays it to the ECU (engine control unit) and impacts the operation of several independent systems. Officially, a tachometer is a device that measures the rotation of the engine’s crankshaft, which is responsible for rotating each connecting rod and piston through the combustion cycle. As the crankshaft spins 360-degrees, it completes a revolution. The total of crankshaft’s rotation speed is measured in revolutions per minute, or RPM.

The RPM is displayed on a gauge, typically located in the driver dashboard instrument cluster and, in most cases, on the left-hand side. It usually shows a series of numbers from zero to 8 or 9, with multiple lines in-between each whole number on an analog or digital display. The whole number 0 through 9 is actually defined as 1,000 times that number. The final numbers displayed on the tachometer gauge are typically notated in red. As the engine accelerates, a needle will point to the number that equals the engine’s RPM. When the needle is pointed in the redline section, it’s considered to be “red-lining” or operating higher than recommended.

Knowing the tachometer's function, let's look at the top 4 reasons it's important to vehicle operation.

1. Captures and Relays Data to Help Shift Your Vehicle

If you have an automatic transmission and have a tachometer gauge, you’ll notice some consistency when shifting from a lower gear to a higher gear. The transmission is programmed to shift up to higher gears at predetermined engine RPM. The RPM is measured by the tachometer and relays data to the TCM (transmission control module) or ECU. That same RPM is displayed on the gauge. While the gauge itself is simply for display, it lets the driver know when to expect a shift.

2. Let’s Manual Transmission Drivers Know when to Shift

The tachometer gauge also helps a driver know when to shift each gear while driving a manual transmission. Most manually-shifted cars, trucks, and SUV’s should be shifted from a lower gear to the higher gear when the engine RPM gauge displays 3,000 to 4,000 on the tachometer. Driver’s are usually trained to shift the engine based on sound and driving conditions as opposed to the tachometer RPM, but the tach serves an important function by providing a visual indicator.

3. Helps Improve Fuel Efficiency

A working tachometer can also help those with manual transmissions improve their fuel mileage. Most automotive manufacturers will note in the vehicle’s owner manual at which RPM the engine should be shifted for optimal efficiency. To achieve optimal efficiency, today’s modern combustion engine is paired to a specific type of transmission, or transmission gear and gear drive axle ratio. The combination of all three individual systems is known as the power train. Shifting when recommended by the manufacturer helps supply power to the wheels with as little drag as possible. With a reduced “load” or “drag” on the engine, less fuel is burned — improving fuel economy.

4. Extends Engine Lifespan

A combustion engine contains multiple moving parts that all require lubrication in order to operate. As each part moves, friction and in turn heat is created with every engine revolution. The faster the engine spins (or higher the RPM), the more heat will be created. When this occurs, metallic parts that touch will eventually heat until they begin to lose lubricity, which can result in catastrophic failure. When the tachometer and supporting components are working correctly, the transmission can shift on time or drivers with manual transmission can shift as recommended — prolonging engine lifespan.

The tachometer plays a vital role in today’s modern engine by going much further than a moving needle on a display gauge. If you notice the tachometer gauge is not working, it can be a sign of a minor issue, such as a broken gauge or loose wire, or a potentially major problem, such as a damaged timing sensor. If you suspect the tachometer is not working on your car, contact a professional mechanic and have them diagnose what is causing the failure so the right repairs can be completed.


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Raymond

27 years of experience
108 reviews
Raymond
27 years of experience
Suzuki XL-7 - Crankshaft Position Sensor - Apple Valley, California
I am pleased all around. Raymond did great work in a timely manner. He even saved me money on the job because my car didn't need the work the previous mechanic said it did. My car is up and running again ! I will certainly use Raymond again.
Chrysler 300 - Crankshaft Position Sensor Replacement - Adelanto, California
Raymond was a very professional and knowledgeable person. I was comfortable in his presence and I don't trust most. Very good experience.

Chris

22 years of experience
2001 reviews
Chris
22 years of experience
Mercedes-Benz S550 - Crankshaft Position Sensor - Winchester, California
Chris is extremely informative goes well above and beyond to make sure everything is done to the highest level per Mercedes- Benz I am so happy that I am dealing with Chris and your company referrals will follow!
Nissan 350Z - Crankshaft Position Sensor Replacement - Laguna Niguel, California
Chris is very knowledgeable. He did a great job getting my car repaired and made sure everything was working before leaving. Will definitely use Chris again.

Shawn

12 years of experience
152 reviews
Shawn
12 years of experience
Buick LeSabre - Crankshaft Position Sensor - Hamburg, Pennsylvania
Shawn was very knowledgeable, , professional, and efficient. I would recommend him to my family and friends!
Saab 9-5 - Crankshaft Position Sensor - Spring City, Pennsylvania
Shawn Is amazing, he is not only on time (this is the 4th service i have done with Shawn) but he is polite and very professional. I will recommend Shawn to all of my friends and family. If you get the chance to book Shawn dont hesitate one bit. he is the only mechanic i let touch my saab or my wife Hyundai period.

Jason

15 years of experience
344 reviews
Jason
15 years of experience
Toyota Camry - Crankshaft Position Sensor - Brooklyn, New York
This guy knows his work. Although he was late for the appointment, he arrived and was prepared. He made sure to tighten all bolts. My car was shaking before but after securely tightening all bolts, the car began running smoothly.
Volkswagen Passat - Crankshaft Position Sensor - Ridgewood, New York
My vw passat b6 had surged and rpm issues for a couple weeks and finaly died left me on the street and unable to start. Jason replaced my camshaft and crankshaft sensor and was able to get me back to the road in no time for the price that i would pay only the tow truck to go to shop. He has his all garage fully equipped in his car . After replacing parts and starting my car. He did 50 point check ,test drive the car making sure everything running good and gave me some awesome advices. Very proffesinal, frendly and knowledgeable.. I Highly recomeding Jason for any kind of car issue that you want to be solved while you watching tv in comfort of your home!

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