Operating Instructions - Snap-on Equipment

Interpretation• Minimal NO is produced while an engine idles.• An excess of O 2 reduces HC and CO emissions.• A deficiency of O 2 reduces NO.• NO forms in the combustion chamber at peak temperatures 2500°F (1370°C).Air-Fuel Ratio EffectsFigure 5-1 contains some of the results possible when the air-fuel ratio issustained at conditions ranging from too lean to too rich.CONDITIONToo LeanSlightly LeanStoichiometricSlightly RichToo RichFigure 5-1: Air-Fuel Ratio Conditions and ResultsCorrection FactorsCorrection factors are applied in some cases to compensate for environmentalconditions that might influence emissions test results.Dilution Correction FactorsWhen using the Dilution Correction Factor (DCF) to report I/M results, select aDCF preference by choosing DCF ON or OFF.SpecificationsRESULTSPoor engine powerMisfiring at cruising speedsBurned valvesBurned pistonsScored cylindersSpark knock or pingHigh gas mileageLow exhaust emissionsReduced engine powerSlight tendency to knock or pingBest all-around performanceMaximum engine powerHigher emissionsHigher fuel consumptionLower tendency to knock or pingPoor fuel mileageMisfiringIncreases air pollutionOil contaminationBlack exhaustCatalytic converter damageApplication:Certain test resultsPurpose:Corrects for exhaust system leaksGas Values Affected: HC, CO, NOAffect:DCF increases gas valuesFactor Range: 1.0 – 3.05-3