Search Results

The Colorado Department of Health (CDH) collected CO exhaust emissions data from twenty-one vehicles using three “short” emissions tests, and the Federal Test Procedure (FTP). CO data were also collected from these vehicles using a remote sensing system. Excess carbon monoxide emissions were calculated from the difference between FTP measurements and federal standards. Emissions were then categorized by individual vehicle and by vehicle type. Errors of comission and omission were determined for each of the short tests and remote sensing system. The CDH226 showed the highest correlation for identifying vehicles emitting excessive CO. Compared to the FTP, it identified the vehicles responsible for 98.5% of all excess emissions. All the “short” tests and remote sensing tests identified the vehicles producing the majority of excess emissions. The current BAR '84 type idle “short” test and the CDH226 demonstrated the lowest errors of comission, or false failures.

In order to improve previous estimates of the reduction in carbon monoxide achievable in Colorado for oxygenated fuels with various levels of oxygen concentration, the Colorado Department of Health has reviewed several outside studies in addition to examining an in-house data base which contains more than 400 tests on 165 vehicles. Earlier findings such as 1) considerable variability among individual vehicle reductions and 2) a nearly linear relationship between CO reduction and fuel oxygen content for non-catalyst vehicles were confirmed. However, certain other conclusions by outside researchers were not supported by the high altitude data base. These included 1) non linear relationships between CO reduction and fuel oxygen content for catalyst and closed loop vehicles and 2) the fleetwide generalization that CO reductions achievable from fuels containing 2.0 percent oxygen are eighty percent as great as CO reductions achievable from fuels containing 3.5 percent oxygen.