Checking Ethanol Content

Fig 1: Identifying Ignition On Position

Courtesy of VOLVO CARS OF NORTH AMERICA.

HINT: The cause of the symptom and/or diagnostic trouble code may be that the vehicle has been refuelled with incorrect fuel for that vehicle. The fuel system contains fuel with too high ethanol content. 

The energy content in ethanol-diluted fuel is lower than in pure gasoline. This means that the control module compensates for the lower energy content, by increasing the injection volume, to be able to reach lambda=1 at the front heated oxygen sensor. This compensation is normally called "Front lambda control slow" or "Lambda integrator", and varies to compensate for the vehicle's status in the form of component spread, small air leaks, wear, etc. The value of this compensation in the ideal case is 1.0 for pure gasoline. Increased ethanol content of the fuel increases the compensation by approx. 0.05 per 10% ethanol dilution.

The control module is designed to handle an ethanol dilution up to 25%. In combination with other deviations from the ideal case, however, lower ethanol content may be enough to cause customer symptoms. This mainly occurs at engine start with cool engine at outdoor temperatures below 0 °C. Then the diagnostic trouble code may also be set for the engine running on too lean mixture.

• Measure the ethanol content of the fuel according to the instructions below.

  If measured ethanol content is above 25%, then ethanol dilution is the likely cause of the symptom and/or to the diagnostic trouble code being stored.

  If measured ethanol content is below 25%, symptoms and/or diagnostic trouble code may have been caused by earlier occurrence of incorrect fuel in the system for that vehicle.

  HINT: Check refuelling history by talking to customer. 

  If nothing indicates incorrect fuel, neither now nor earlier, continue troubleshooting to check other possible causes of faults.

Other information 

• see MEASURING THE ETHANOL CONTENT

• Continue 

  Refer to CHECKING COMPONENTS