Is Your Customer’s Vehicle ‘Impaired?’

At this particular time gasoline is commercially available in two blends in the U.S.: E10 and E85. E10 refers to gasoline that has been blended with a volume of 10 percent alcohol per gallon [V%]. E10 is the most commonly dispensed fuel. Excluding a few exceptions, all vehicles can operate on E10 blended gasoline.

E85 refers to gasoline that has been blended with a volume of 85 percent alcohol per gallon [V%]. E85 was blended for use in Flex fuel vehicles. Flex fuel vehicles can operate on blended fuels from E10 up to E85.

The EPA has approved the use of E20 for vehicles manufactured from 2001 and newer, but due to ongoing lawsuits, dispensary issues and logistics, implementation of E20 is on hold.

E85 Colorless Winter Grade Fuel No Seperation

The Letter E The alcohol for use with internal combustion engines is called ethanol (Eethyl alcohol), and primarily is made from corn. Because ethanol is derived from feedstock that is grown, it is considered a renewable fuel. The ethanol blend dispensed at the pumps is regulated. The signage on the pump will display the volume content of ethanol per gallon [V%] of gasoline being dispensed. At the end of 2010, more than 90 percent of all gasoline sold in the U.S. was blended with ethanol.

Each ethanol molecule contains 35 percent oxygen. Blending ethanol to gasoline is adding a liquid oxygenator.

This article is a discussion of a vehicle operating “impaired” due to an excessive amount of alcohol in the fuel system of the vehicle. With the blended gasolines commercially available to the consumer, what type of vehicle do you think would be most affected by excessive alcohol, a flex fuel vehicle or a non-flex fuel vehicle?

With a non-flex fuel vehicle, the ideal alcohol percentage in the fuel should fall between 7 to 10 percent. If the alcohol percentage becomes greater, fuel control issues can result.

As a diagnostic technician, I am hired when the diagnosis becomes stalled or the vehicle has returned repeatedly for the same initial complaint. I am a strong believer of covering the basics and performing the simple tests that will give you a base line of the vehicle regardless of the system being diagnosed. This thought process can save valuable shop time and prevent replacement of known good components in an attempt to locate the root cause of the complaint. Let’s take a look at an example.

A Hungover Honda
A 2009 Honda CR-V was brought into a local repair facility with a customer concern of an illuminated Malfunction Indicator Lamp (MIL) preventing a yearly state inspection from being performed. The vehicle has a 2.4 liter engine with approximately 80,000 miles. During the diagnosis the technician finds a stored fuel trim control fault (P0171).

Additional Ethanol Test Example If Needed

For a P0171 test to fail, the long term fuel trim (LTFT) and short term fuel trim (STFT) have had to had reached or exceeded a pre-programmed threshold set by the manufacturer (LTFT > 25 percent, STFT > 5 percent, for example).

The two screenshots (taken from the Honda factory scan tool) contain all the information I needed to verify the complaint.

The factory tool has guided fault help. Is excessive alcohol in the fuel supply listed under possible failures? Well, kind of if you read the “fuel does not meet O/M specifications” cause with a broad definition.

Looking at the data displayed, what do you notice about the fuel trim (both short term and long term)? Does it verify the P0171 failed test?

The total fuel trim (STFT and LTFT=1.49) is +49 percent! Yes, I’d say the code is verified.

If this Honda CR-V vehicle came into your repair facility, what would your first diagnostic step in locating the root cause of the P0171 be?

April 2015 Multimeter Connected To Tester And Zerod Prior To Testing

• A smoke test of the intake system.

• A fuel pressure and possible volume test.

• Scope and inspect the MAF sensor (if equipped).

• Graph the data PIDs under various RPM and load ranges.

• Clear the fuel trims and road test the vehicle.

As a diagnostic technician, I typically will interview the driver of the vehicle whenever possible. Next, I will record all the vehicle information as well as the stored and current information and data. Then I will verify the complaint. What is important to know on this Honda is that the customer voiced no drivability concerns, only that the MIL was on and it wouldn’t pass the state inspection requirements.

After I’ve verified the customer’s concern, I typically will perform a Keep Alive Memory (KAM) clearing procedure and test drive the vehicle again while monitoring the fuel trim data to see if the P0171 failed test is a hard fault or intermittent occurrence. (A second road test will illuminate the MIL if P0171 is a hard fault).

With this vehicle the Total Fuel Trim (TFT) was greater than +45 percent, and the MIL was again illuminated during the second consecutive road test.

Let me ask you a few questions.

If the TFT stayed high; greater than +45 percent during all rpm and load conditions, would you ever consider an excessive alcohol percentage issue?

I find in most cases this is not considered or is the last possible scenario the technician would bother considering during his/her diagnosis. In years past I had overlooked this possible issue, and wasted valuable diagnostic time. Now it is part of my basic testing for fuel system control (DTCs) failed tests.

Ethanol Percentage 25 With Color Added To Fuel Much Easier To Detect Seperation

We need to remember there is a low fuel volume demand at idle. The fuel demand will increase with rpm and load. If a fuel delivery issue caused the P0171, the adjustment would increase substantially with RPM and load.

With a fuel trim correction of more than +45 percent, is the engine management system in fuel control, or is it impaired? (Is it operating normally? Can the engine management system keep the air/fuel mixture at stoichiometric during normal operating conditions?)

This is where a simple alcohol test of the vehicle’s fuel supply can reveal a lot of valuable information. (Note: Do not drain the fuel filter for a fuel sample to analyze. It would be best to take a sample prior to the fuel filter if possible.) By checking the fuel sample, you can learn if there is:
• Excessive percentage of alcohol in the fuel.
• Rust/debris in the fuel.
• Excessive water in the fuel (ethanol is hydroscopic).

This simple test can either confirm there is a problem with the fuel supply or eliminate the fuel supply as being the root cause.

Ethanol Percentage 30 With Winter Grade Fuel Due To Colorless Harder To Detect Seperation

Diagnostic tip: Larger percentages of ethanol greater than E10 in the vehicle’s fuel system of a non-flex fuel vehicle will cause the fuel trim values to increase (positive correction) as the ECM attempts to keep the air/fuel mixture at stoichiometric. Also, my experience is that large percentages of alcohol in late model vehicles equipped with Wide Band Oxygen sensors (these sensors can provide actual air /fuel mixtures as rich as 9.0:1 and as lean as 2.0:1) can illuminate the MIL due to a fuel control failed test (DTC) without any drivability complaints or symptoms, as with the case study vehicle; 2009 Honda CR-V.

For reference, look at the image of the alcohol percentage test. This is clearly a case of excessive ethanol in the vehicle’s fuel supply. This higher than normal ethanol percentage could have been a dispensary issue (wrong fuel in the station’s tank) or human error (didn’t read the pump) on the customer’s part. Either way, our real concern is only to locate the root cause of the customer’s complaint of MIL illumination.

Now, what two options are available to us for properly repairing this vehicle? We could drain the fuel tank and refill with properly regulated

These would be our two repair methods, both with the same goal of replacing the fuel in the tank. (The second option would require some patience of the customer.)

If the alcohol percentage is higher than regulated with (E10) fuel, it would not be an issue what-so-ever with a flex fuel vehicle because the engine management system is designed to operate on an alcohol percentage rate as high as 85 percent (E85). It would be more of an issue with the non-flex fuel vehicles. If we overlook a basic fuel test of the vehicle’s fuel supply and the root cause of a fuel system failed test (DTC) is a higher than normal alcohol percentage, there is the strong possibility techs would attempt to correct the lean condition through the replacement of known good components (MAF sensors, HO2sensors etc.). There is also the possibility of consuming excessive shop time.

Tools for This Trade
There are several fuel test kits available through the OEMs and the aftermarket. Here are two examples of fuel test kits and how to use them.

The BG Fuel test kit: Below Image; contents of the BG Fuel test kit (for Gasoline and Diesel fuels). There are three quick steps for the alcohol percentage test using the gasoline fuel graduated cylinder. After you shake the graduated cylinder, let it sit for a minute, so the ethanol has time to separate from the actual gasoline.

We also have illustrated “excessive” ethanol percentage in the vehicle’s fuel system containing E10. (Note the lack of color in the fuel. I see this with winter grade gasoline). Remember either (E10) or (E85) is being dispensed at the pump at this time; even though (E20) has been EPA approved. The below example of ethanol percentage in the fuel supply, would be too low to be considered (E85).Remember; the above pictured; alcohol percentage will create failed Fuel System tests (DTCs) in non-flex fuel vehicles. When shops or technicians call me describing

an elusive fuel system failed test (DTC), the alcohol percentage typically is in the lower to mid-20 percent amount.

The SPX Kent –Moore fuel tester. Performing the ethanol percentage test with this type of tester is a simple and quick test. There are only three quick steps to using this fuel tester.

First, connect multimeter leads to end of tester handle (lead polarity is shown on

tool). Place the meter selector on the Hz setting and zero the meter. Note: Remember to zero the multimeter prior to each test. Second, pour the fuel sample into the test cavity (opposite end of handle as previously shown) and turn the tester on.

Third, observe the Hz value on the multimeter. Then remove 50Hz from this value to obtain the ethanol percentage in the fuel sample.

I had a technician at a repair facility I frequently visit inform me of the root cause of a no start he had been working on. The vehicle was non- flex fuel vehicle. I had shown him in the past how to determine the ethanol percentage in fuel so when he performed the test on the vehicle’s fuel supply, he found the fuel blend was actually (E85). Interviewing the customer revealed that the tank was low and filled by the customer (this is where human error becomes a factor). Within a short distance the engine started running rough, and the MIL illuminated on the dash. The vehicle became a no start and was towed to the shop for a diagnosis. The tank was emptied and the fuel replaced with (E10). A new fuel filter was installed, and a KAM procedure was performed. The vehicle was road tested without any further issues.

Here are some other tips to keep in mind when you suspect a fuel quality problem on your customer’s car.

• Alcohol fuel is clear in color, and not dyed as gasoline usually is.

• At greater than 35 percent, ethanol percentage in the vehicle’s fuel supply, there is a distinct alcohol odor from the gas tank with filler cap removed.

• With high ethanol percentage in the vehicle’s fuel systems of a non-flex fuel vehicle; a distinctive smell is present from the tail pipe while vehicle is running, and a light whitish color smoke can occur during periods of acceleration.

• Remember; ethanol is hydroscopic and will mix with water. Long time storage of ethanol blended fuel should be in a sealed container to prevent the ethanol mixing with the moisture in the atmosphere (similar too brake fluid for example).

Remember; do not overlook the basic test procedures.

• Visual inspections (unsecured engine harnesses. loose, worn or missing components). If you notice recent work performed with new components installed especially sensors; take a moment to verify the component(s) is the correct one for the vehicle.

• Checking the charging system and cabling. (Battery connection, and V/drops).

• Fuel volume testing (remember you can have the correct pressure but with low/no volume).

• After diagnosing and replacing a faulty component that is creating a fuel system failed test to occur, perform a KAM clearing procedure before you retest the vehicle.

• Keep in mind that with some late model flex fuel vehicles it might take several miles before the engine management system can relearn the ethanol percentage.

Basic test procedures on any of the systems of a vehicle could save you valuable shop diagnostic time, and prevent replacement of known good component. Also could prevent the vehicle from returning to your shop with the same initial complaint.