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Increasing pressure on lowering vehicle emissions to meet stringent California and Federal 1993/1994 emission standards (TLEV) of 0.125 gpm NMOG, 3.4 gpm CO and 0.4 gpm NOx and future ULEV emission standards of 0.04 gpm NMOG, 1.7 gpm CO, and 0.2 gpm NOx has focused specific attention on the cold start characteristics of the vehicle's emission system, especially that of the catalyst. From test data it is evident that the major portion of the total HC and CO emissions occur within the first two minutes of the driving cycle. The use of an electrically heated catalyst (EHC) is shown to be advantageous in lowering cold-start emissions during this portion of the drive cycle. This paper addresses the effect on emissions from the standpoint of EHC location, catalyst volume, and engine calibration in an overall emission system approach.

Vehicle emissions have been measured and the results statistically evaluated for a vehicle test fleet consisting of four Escorts and four Explorers using both methylcyclopentadienyl manganese tricarbonyl (MMT) at 1/32 gram Mn/gallon and clear (MMT free) fuel. The fleet was divided in half -- half with MMT and half without MMT doped fuel. This interim report covers emission measurement results at 5,000; 15,000; and 50,000 miles of exposure to MMT doped fuel. The planned mileage accumulation is for 100,000 miles of durability and exposure to MMT based fuel. A modified paired t-test is used to analyze the emission data obtained from all the fleet vehicles. The statistical evaluation of both feedgas and tailpipe emissions indicated that the use of MMT is detrimental to emissions of HC at both the 15,000 mile and 50,000 mile levels of MMT exposure. Indications also are as mileage is accumulated, the worse the effect on HC by MMT.

Prototype metallic and electrically heated metallic catalysts (EHC) are being evaluated on a gasoline fueled vehicle. The vehicle used for this evaluation is a 5.0L Mustang equipped with an emissions control system which includes mass air, and sequential electronic fuel injection (SEFI). FTP tests are performed to evaluate non-heated metallic and electrically heated metallic catalysts in both production and close-coupled configurations. The objective of the evaluation is to determine light-off characteristics of both the non-heated metallic and the EHCs and their effect on cold-start emissions (Bag 1). FTP results are compared to those obtained from conventional ceramic catalysts in the same configurations. Initial data show some emissions benefits for the prototype EHC converter during the first 60 seconds or so of the FTP. From 60 seconds on in the FTP cycle, the ceramic catalyst was slightly more efficient, leading to overall FTP emissions about the same for the two systems.