Chevy 6.6 Gas Problems

Chevy 6.6 Gas Problems: Troubleshooting Issues (Solutions)

Lately, my neighbor got stuck in a problem he was facing with his Chevy 6.6 gas engine.

The engine kept making knocking noises, and its fuel management was poor.

After trying a few tweaks, I helped him get over the problem. This incident inspired me to write on this topic.

In this article, I discussed all the common Chevy 6.6 gas problems along with their fixes.

Top 10 Chevy 6.6 Gas Problems

Chevy 6.6 Gas Problems

These are the Top 10 Chevy 6.6 Gas Problems:

1. Insufficient Amount Of Horsepower

Based on the original specifications and features of the Chevy 6.6, it has been observed that the engine does not deliver a satisfying amount of horsepower.

Chevy 6.6 gas engines have a horsepower of 401, 5200 RPM, and a torque of 464 lb-ft.

On the other hand, its competitor, Duramax 6.6l, has a horsepower of 445, 2800 RPM, and its torque is 910 lb-ft.

Solution for Insufficient Amount Of Horsepower in the Chevy 6.6 gas engine

The best way to increase the HP of the Chevy 6.6 gas engine is by replacing it with another e fine with a higher horsepower specification.

However, there are also a couple of installations that can help in fixing this Chevy 6.6 gas problem. These include:

  • Supercharger or turbo kit
  • Performance engine tuner
  • Aftermarket exhaust system

You can also clean the fuel injector to increase the vehicle’s HP.

Refer to this Chevy 350 engine diagram if you face any issues with it.

2. Poor Acceleration

As a result of the low horsepower associated with Chevy 6.6 gas engines, the acceleration of the vehicle is weak. This is because the acceleration of the vehicle depends on its horsepower production.

The more the HP, the more acceleration, and vice versa.


You can correct this Chevy 6.6 gas problem by performing the following:

  • Cold air intake installation
  • Installation of a throttle response controller.
  • Tuning the Engine Control Unit (ECU)
  • A reduction in the weight of the vehicle can also help in boosting its acceleration.

If you’re looking to boost your Chevy’s performance to hit that sweet 500 HP mark, you might want to check out our article on the Best SBC Heads for 500 HP.

3. Poor Transmission Speed

When compared to the transmission speed of its competitors, the transmission speed of the Chevy 6.6 gas engine is low.

Most engines have 8 to 10 speed transmission systems, while the Chevy 6.6 has a 6 speed automatic transmission system.


The most reliable and effective fix for this Chevy 6.6 gas problem is replacing the Chevy 6.6 transmission system with an 8-speed or 10-speed transmission system.

4. Low Towing Capacity

When compared to the towing capacity of a 6.6 diesel engine, the towing capacity of the Chevy 6.6 gas engine is found to be 4000 pounds less.


Just like the acceleration is affected by the horsepower of the engine, the towing capacity is affected as well.

For this reason, increasing the horsepower of the Chevy 6.6 gas engine will provide an increase in its towing capacity. The increase can be up to a thousand pounds in towing capacity.

5. Production Of A Knocking Sound

This Chevy 6.6 gas problem usually occurs when there is an issue with the engine’s knock sensor.

Problems with the knock sensor can lead to the uneven burning of gasoline in the cylinder, which causes the release of a knocking sound from the Chevy 6.6 gas engine.


This Chevy 6.6 gas problem is not so severe. As a result, there are a couple of ways to reduce the knocking sounds coming from your Chevy 6.6 gas engine.

  • Refill the engine with at least eight quarts of full-synthetic engine oil.
  • In the most severe case of this Chevy 6.6 gas problem, replacing the knock sensor may be necessary.

6. Low Gas Mileage

The gas mileage of the Chevy 6.6 gas engine is not the best in the engine market.

The issue of low Gas mileage is one common problem encountered by the users of Chevy 6.6 gas engines.

Low gas mileage means that the engine burns a lot of gas to function.


Here are some things you can do to help reduce the amount of gas consumed by your Chevy 6.6 gas engine:

  • While driving, make sure that the vehicle is in 2WD mode. This will help you save gas because the vehicle burns less gas when set in the 2-wheel driving mode (2WD).
  • Ensure you replace your air and oil filters as and when due.

7. Poor functioning Valves And Lifters

Complaints regarding the poor function of the engine’s valve and lifters have been made by Chevy 6.6 gas engine users.

Asides from the problems with the functioning of the valves and lifters, it has also been noted that the lifespan of these engine parts is lower than average.


You can try changing the valves and lifters of your Chevy 6.6 gas engine with another one with a better function and lifespan.

8. Low Acceleration Power

The normal function of an alternator in a vehicle is to charge the battery and to pass electrical current through the entire vehicle’s system while it is driving.

The alternator of a Chevy 6.6 gas engine does not have high power.

Therefore, it requires a longer period to fully charge the battery after the Chevy 6.6 starts running.


Simply replace the low-powered alternator with another one of high power.

9. Malfunction Of The Throttle Body Sensor

This Chevy 6.6 gas problem causes the Throttle Position Sensor (TPS) to send the wrong air-flow reading to the ECU. As a result of this erratic reading, the air-to-fuel ratio becomes incorrect.

Thereby causing the fueling system to send more it less fuel than is required to the engine.


Do the following to fix the Malfunction Of The Throttle Body Sensor:

  • Check the sensor’s position and make sure it is properly placed.
  • Clean the throttle position sensor properly.
  • If the above mentioned steps do not help out, consider replacing the sensor.

10. Low Transmission Speed

The transmission speed of the Chevy 6.6 gas engine is not usually the best as there are higher transmission speeds that perform better than that of the Chevy 6.6 gas engine.


This Chevy 6.6 gas problem can be managed by doing the following:

  • Periodic servicing of the transmission; improves longevity.
  • Make sure that the tire is aligned properly.
  • Ensure that you are using the correct tire size.
  • While driving with heavy loads, lower the gears.

If you’re experiencing issues with your 2013 Chevy Cruze, Check out my post on 2013 Chevy Cruze Problems to learn about the potential problems that this particular model may have.

How to Identify Chevy 6.6 Gas Problems

How To Identify Chevy 6.6 Gas Problems

Follow these steps to spot Chevy 6.6 gas problems:

  1. Production of a knocking noise, a ticking sound, and/or a valve noise.
  2. The vehicle consumed power excessively.
  3. Damage to the lifters and valves.
  4. Rough idling of the vehicle.
  5. Misfiring of the engine.

Chevy 6.6L Gas Reliability

Chevy 6.6L Gas Reliability

Though a good number of Chevy 6.6 gas problems have been noted, the engine remains reliable. In addition, most of the problems associated with the engine are not so severe and require easy fixes. So, the engine is not so bad after all.

Is Chevy 6.6 a Good Gas Engine?

Is Chevy 6.6 A Good Gas Engine

From my point of view, a reliable engine is a good engine. The Chevy 6.6 gas engine is cheaper than the diesel engine and also functions at a satisfactory level. However, if you are looking for more power and performance, a diesel engine is what you need.

FAQs on Chevy 6.6 Gas Problems

These are the most frequently asked questions on Chevy 6.6 gas problems:

How can I prevent overheating in my Chevy 6.6 gas engine?

Regular maintenance including checking coolant levels, ensuring the radiator is functioning properly, and timely oil changes can help prevent overheating.

What might cause a misfire in my Chevy 6.6 gas engine?

Misfires could be due to a variety of issues such as worn out spark plugs, faulty fuel injectors, or issues with the ignition coil. It’s best to get it checked by a professional mechanic.

How often should I change the oil in my Chevy 6.6 gas engine?

Chevy recommends an oil change every 7,500 miles or 12 months, whichever comes first. But this may vary based on driving conditions and usage.

What can cause fuel pump failure in the Chevy 6.6 gas engine?

Fuel pump failures could be triggered by contaminated fuel, infrequent changes of the fuel filter, or simply the age of the vehicle.

If you recently rebuilt your 4L60E transmission, but are now you’re experiencing unexpected issues, Check my post on 4l60e Transmission Problems After Rebuild to address these concerns promptly.


Just as was stated earlier, Chevy 6.6 gas problems are not so severe and can be fixed or managed easily. Also, you need to remember that no car is perfect. Every car owner has a problem to deal with. So, experiencing problems with your Chevy 6.6 gas engine is white normal. As long as you maintain your vehicle properly, the engine will serve you well. It may not be the best, but it is good and reliable.

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