Seasonal Fuel Blends -

Seasonal Fuel Blends

The cause of the misfires is the temperature fuel evaporates, otherwise known as the volatility.

Have you seen an uptick in misfire codes or engines running rough at your shop in April or October? You might think it is the spark plugs or even ignition coils. However, the real cause could be seasonal fuel blends. 

In some areas of the country, when the gasoline blends change from winter to summer or summer to winter, some turbocharged and/or direct injection engines have problems. 

The cause of the misfires is the temperature fuel evaporates, otherwise known as the volatility. 

Gas is gas, right? No. 

Summer blends are designed to evaporate at higher temperatures to prevent evaporative emissions. During winter, they change the mix to be more volatile at lower temperatures for improved cold starts and lower start-up emissions. Gasoline distributors will change the formulations typically in late September and early April. But, it is difficult to predict the weather. 

A warm day in October or a cold day in April can cause issues with these fuels and generate random or specific cylinder misfire codes. Also, other codes can help you determine if it is a fuel or ignition issue. Or the problem could be what some gasoline formulators call “overhang” when the supply of winter or summer lasts longer than expected. 

The fuel’s volatility can directly impact how the flame front propagates inside the cylinder under certain conditions like cold starts and high loads at specific engine speeds. One of the most common symptoms described is misfires when the vehicle is traveling at freeway speeds when the engine is between 2,000 and 3,000 rpm. 

Freeze frame information can give you valuable insights when a misfire occurs. Look at engine speed, vehicle speed and coolant temperature. Some vehicles will include the ambient temperature in the freeze frame information.

Another code set could be P0316 for misfires detected during the first 1,000 revolutions. This can be caused by the lack of fuel in the rail or the volatility of the fuel at low or high temperatures. Again, look at the freeze frame information. Code P0316 is typically set in open-loop operation and before the oxygen or air-fuel ratio sensor is at operating temperatures. It is also a sign that the current conditions do not match the long-term fuel trims. These factors could include poor-quality fuel for the conditions.

Winter blend fuels in warm weather can cause extended crank times because the higher underhood temperatures can evaporate the fuel from the rail and injectors. If the engine has direct injection, the fuel can evaporate in the low side of the injection system, and it might take extra time to prime. Some OEMs might set a code for extended crank time.

What is the cure? Simple, Maintenance. Today’s import nameplate turbocharged and direct-injected engines operate on a very fine line between maximum efficiency and a misfire. Any changes to the inputs like air, fuel or spark can cause a misfire and codes. 

Let’s say the coil is degraded and the secondary can’t generate enough current to cause a spark in the cylinder, it could cause a misfire. The same is true for a worn spark plug. Poor-quality fuel just exacerbates the condition of the ignition system. Carbon deposits and even clogged fuel injectors can also be contributing factors.

If you get a car in with misfires and other misfire-related codes at the start of winter or the beginning of summer, it could be an issue with the gasoline in the tank. But, before you blame the gas, take a look at the codes and take a look at the maintenance performed.

You May Also Like

Understanding Differences Between Aluminum And Cast Iron

Sheer material differences aside, what are the features and benefits of aluminum and iron engine components?

It doesn’t take a rocket scientist to realize that the rising cost of raw materials and supply chain disruptions over the last few years would transform our industry. However, we never envisioned the sudden demand for billet blocks to surpass that of cast iron or aluminum. The cost of cast aluminum blocks are creeping ever closer to that of their billet counterpart, therefore the additional expense is now a reasonable and practical upgrade for our racers. 

The Latest on Lifters

Advancements in technology, as well as modern testing and research is constantly evolving to make lifters better.

Understanding Underhood Parts for Hybrids

Anything that can happen to an ICE in a standard vehicle can happen to an ICE in a hybrid.

Engine Building 102 – Building The Perfect Top End

Join Doug Kaufman and the experts at Summit Racing for a livestream on November 29 at 1PM EST.

Taking The Guesswork Out Of Building Rotating Assemblies

Rotating assemblies can be a guessing game as you struggle to find the right option for your project.

Other Posts

Understanding Fuel Injection

Though many different terms have been used for the technology, it really just comes down to indirect or direct.

Electronic Throttle Body Service

On most systems, idle speed is completely controlled by the throttle plate angle.

Adapting Sensors For Changing Inputs

Let’s focus our attention today on one small facet of the technology inside modern vehicles: Adaptations.

Carbon Deposits In Direct Injection Engines

The primary cause of these problems is that fuel and added detergents are not hitting the back of the intake valves.