摘要: |
The goal of the Coordinating Research Council (CRC) E-87-1 Mid-Level Ethanol Blends Catalyst Durability Screening Study was to identify vehicles which used learned fuel trims to correct open loop air-fuel ratios. The Coordinating Research Council (CRC) E-87-1 Mid-Level Ethanol Blends Catalyst Durability Screening Study is the first phase of a two phase program to develop data on the durability effects of mid-level ethanol blends on emission control systems. The second phase consists of aging vehicles identified during this screening study to full useful life with mid-level ethanol blends to determine their durability effects. Twenty-five vehicles were evaluated as to whether they adjusted their fueling with increased ethanol content to maintain a consistent fuel:air equivalence ratio in open loop control. The assessment method for this study was the same as that used in the recently published Department of Energy screening test program, 'Effects of Intermediate Ethanol Blends on Legacy Vehicles and Small Non-Road Engines, Report 1 - Updated'. Thirteen of the twenty-five vehicles did not adjust open loop fueling to compensate for ethanol in the fuel. Eight of the twenty-five vehicles did adjust open loop fueling to compensate for ethanol in the fuel. Four of the twenty-five vehicles gave unclear results. The thirteen vehicles (and potentially the four that could not be analyzed or gave ambiguous results) that do not adjust for ethanol in open loop control are likely to have their fuel enrichment operation compromised when operated on mid-level ethanol blends. As was documented in the Australian ethanol durability study, this can lead to catalyst performance degradation and increased harmful exhaust emissions. In addition, the durability of the engine and other systems may also be compromised. |