1. Determining how close the A/F ratio is
to the stoichometric point using
exhaust gas analysis.
Presented to East Bay ATA, Hayward, CA
May 5, 2004
By: Robert J. Schrader President, Bridge
Analyzers, Inc.

2. point.ricstoichometperfectthe-balanceinare
O2forDemandeCombustiblandO2when1.000toequalisLamdba
oxidation.completeattaintoO2forDemandeCombustibl
thevsProcessCombustionthetoavailableO2ofratiotheisLambda
)(
OxygenfordemandesCombustibl
availableOxygen
Lambda
• Lambda is Oxygen Balance

3.  Lambda control is necessary for peak
combustion efficiency in the Engine.
 Lambda control is necessary for peak
CAT efficiency.
 Lambda Control Improves
Reliability, Fuel Economy and Lowers
Emissions.

4.  Engine out CE for Gasoline Fuel is no better
than 95%.
 Tailpipe-out CE for CAT equipped vehicles
improves to 99.0-99.5%.
 Factor of 10 improvement
 Required for Current Emission Standards
 CAT CE is very Lambda-Dependent

5. 0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
0.90 0.91 0.92 0.93 0.94 0.95 0.96 0.97 0.98 0.99 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10
Lambda
%Concentration
CO - Carbon Monoxide
H2 - Hydrogen
O2 - Oxygen
11.00
11.50
12.00
12.50
13.00
13.50
14.00
14.50
15.00
15.50
16.00
0.90 0.91 0.92 0.93 0.94 0.95 0.96 0.97 0.98 0.99 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10
Lambda
%Concentration
CO2 - Carbon Dioxide

6. 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.950 0.960 0.970 0.980 0.990 1.000 1.010 1.020 1.030 1.040 1.050
Oxidation Efficiency
Reduction Efficiency

7. 0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0.950 0.960 0.970 0.980 0.990 1.000 1.010 1.020 1.030 1.040 1.050
0
100
200
300
400
500
600
700
800
900
1000
H2 - Hydrogen
NOx - Oxides of Nitrogen
CO - Carbon Monoxide

8.  NOx Reduction Bed
 Requires Lambda to be not greater than 1.020.
 CO/HC Oxidation Bed
 Requires Lambda to be not less than 0.980.
 Modulation Depth
 Cycles Rich and Lean Between the Limits Above.

9. point.ricstoichometperfectthe-
balanceinaredemandeCombustiblandO2when1.000toequalisLambda
oxidation.completeattaintoO2fordemandecombustibl
thetoO2)(asavailableOxygenofratiotheascalculatedisLambda
)(
OxygenfordemandeCombustibl
availableOxygen
Lambda

10.  Lambda = 1.000 when the Oxygen available and
Combustible Oxygen demands are in balance.
 This is the point of perfect stoichometric
balance.
 At this point the A/F ratio is 14.71 to 1.00 for
Gasoline.
 Thus, A/F = 14.71 x Lambda

11.  Brettschneider Lambda uses all the oxygen-
bearing and combustible-bearing gases.
 Balance Equation - Calculation not affected by
the degree of oxidation.
 Method is insensitive to combustion efficiency.
 Either Pre-CAT or Post-CAT gases may be
used.

12.  = 1.000 when Oxygen available and
Combustible demands are in balance.
 ECM controls =1.000 at 0.5-1.0 Cycles/Sec
using ‘lambda sensor’ input.
 3-Way CAT operation requires 0.980 to
1.020
 Lambda can be confirmed by exhaust gas
measurement, either pre or post CAT.

13.  calculated from exhaust gas indicates air-fuel
mixture independent of the engine controls.
 calculated from exhaust gas indicates air-fuel
mixture independent of combustion efficiency.
 Cold (Open Loop) vs Hot (Closed Loop) vs
CAT light-off operation can be evaluated.
 can be used to tune systems which do not
have closed-loop control.

14.  High Combustion Efficiency: Measure O2
post CAT - every 5% air leak adds 1.0% O2 to
gases.
 Low Combustion Efficiency: Add CO and
CO2 - should equal 15% for Gasoline.
 Compare both Methods. If O2 indicates air
dilution - then confirm this with low CO and
CO2 sum. They should agree.

15.  Created by iATN Tech Support staff, and
available to iATN members on-line at
http://members.iatn.net/tech/lambda.ht
ml
 Plug and Play either 4 or 5 gas values.
 Can select either US or European gasoline
constants.
 Operates in Java - can be saved and run
off-line by any Java-equipped net browser.

16.  Available as email attached Excel file by
contacting: support@bridgeanalyzers.com
 Plug and Play either 4 or 5 gas values.
 Can select either US or European gasoline
constants.
 Operates on any PC with Excel - can be
saved and run off-line using Microsoft
Excel.

17.  Written by Miles Wada using the
Brettschneider equation - a’la Bridge.
 Available for download at:
http://www.aeswave.com/

18.  Written by Greg Meyer using the
Brettschneider equation - a’la Bridge.
 Available from Greg via email at:
gsmeyer@attbi.com
 Operates on Microsoft PC in Excel.

19. A/F = 14.71 x
Lambda

20.  September
 1993 Mazda Protege
 1.8L, Manual Trans, No EGR
 Failed Smog Check for
Timing (FA99), GP HC & NOx

21. ASM 5015
Result HC CO CO2 NO O2 RPM
GP 247 0.49 13.8 2000 1.2 1624
Standards
HC CO CO2 NO O2
Fail 92 0.55 716
GP 281 2.05 1,961
AVG 21 0.06 150

23.  November
 1993 Mazda Protege
 1.8L, Manual Trans, No EGR
 Failed its Pre-repair Baseline
Inspection at a CAP station
for for Timing (FB48), HC &
NOx

24. ASM 5015
Result HC CO CO2 NO O2 RPM
Fail 186 0.43 16 1095 1 1683
Standards
HC CO CO2 NO O2
Fail 92 0.55 716
GP 281 2.05 1,961
AVG 21 0.06 150

26.  December
 1993 Mazda Protege
 1.8L, Manual Trans, No
EGR
 Passed & Certified

27. ASM 5015
Result HC CO CO2 NO O2 RPM
Pass 74 0.21 15.5 308 0.08 1590
Standards
HC CO CO2 NO O2
Fail 92 0.55 716
GP 281 2.05 1,961
AVG 21 0.06 150