AEM Wideband Failsafe Gauge 304900 User Manual

							Page 12 
4.  With a baseline AFR curve now established, click on Auto Set Limits and the software will 
produce its best suggested high and low AFR limit l ines based on the populated AFR data shown 
on the graph. Review and adjust the high and low AF R limit lines as needed to contour the lines 
around the baseline AFR curve (shown below). This c an be done by clicking on a breakpoint and 
either dragging up or down with the mouse or by cli cking the up and down arrows on the 
keyboard.  To move to the next breakpoint, click on  it with the mouse or use the right and left 
arrows. Pressing the Tab key will toggle back and f orth between the high and low limit lines.  
 
    
5.  Test the configuration using your anticipated no rmal operating conditions with varying engine speed  
and engine load situations to account for starting,  stopping, accelerating, high boost, low boost, tip in, 
fast shifts, slow shifts, etc. If false triggers oc cur, either adjust the high or low AFR curve up or  down 
at the pressure breakpoint where the alarm occurred  or adjust the Alarm Delay setting.  
 
NOTE: There are two general configuration strategie s to follow when using the W ideband Failsafe.  The 
high and low AFR limit lines can be set very tightl y to the baseline AFR curve and a longer Alarm Dela y 
can be used.  Conversely, the high and low AFR limi t lines can be set further way from the baseline AFR 
curve and a shorter Alarm Delay can be used.  Furth ermore, many tuners may conclude that a rich AFR 
is more acceptable for, safety measures, than a lea n AFR. If true, a looser tolerance can be put into the 
lower limit line as depicted in the graph above. On ly thorough configuration testing will reveal which 
strategy is best for your application. 
   
						

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Data Logger 
  
The Wideband Failsafe has an internal logger that c an store approximately 2.5 hours of data.  The 
system maintains two levels of data logs.  First, a ll AFR data points are stored and downloadable for 
viewing on the AFR vs. Pressure Graph in the W ideba nd Failsafe Configuration tab.  Second, all inputs, 
outputs, and alarm triggers are logged in special l og file format for viewing with the AEMdata softwar e 
that comes as part of the Wideband Failsafe downloa d package.  Once the logger memory has filled up, 
the logger will begin to loop log and the oldest da ta will be discarded as new data is collected (data  points 
that were collected will slowly start disappearing) . The following is a basic guideline on how to use  the 
internal data logger.  NOTE: The internal data logg er is always running when 12V is present. 
  1.  Connect USB cable to PC.   
2.  In the W ideband Failsafe Configuration tab under  Logger, click Download Log.  All logged 
AFR data points will now be displayed in the AFR vs . Pressure Graph. 
3.  To download the log to the PC, click YES when pr ompted to save data to disc and then save 
log in desired location. 
4.  Click YES when prompted to open file in AEMdata.  
5.  The saved data log will now open as shown below.  
 
 
               
						

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Plot One 
Parameter Description 
AFR  Current measured AFR (Gasoline) 
AFR Upper Limit  Current upper AFR limit value as set from the Wideband Failsafe Configuration tab 
AFR Lower Limit  Current lower AFR limit value as set from the Wideband Failsafe Configuration tab 
   
Plot Two 
Parameter Description 
Manifold Pressure  Current measured Manifold Pressur e in PSIg 
Engine Speed  Current measured RPM, if connected and  used 
   
AEM EMS Series 1 / Series 2 Parameters 
 
Below is the W ideband Failsafe related parameter names found in the AEM EMS Series 1 & 2 
programmable ECU software when using the AEMNet dai sy-chain. Note the slight difference in 
nomenclature used with the AEM Wideband Gauge. Use the descriptions listed above for detailed 
information. 
 
 
AEM Wideband Failsafe Gauge Name AEM EMS Series 1/Series 2 Name 
AFR [AFR Gasoline]  WBFS AFR 
AFR Upper Limit [AFR Gasoline]  WBFS Up Limit 
AFR Lower Limit [AFR Gasoline]  WBFS Low Limit 
Manifold Pressure [psi]  WBFS Boost 
Engine Speed [rpm]  WBFS RPM 
Alarm Status  WBFS Alarm 
Alarm Reset Limit [ms]  WBFS Alarm Rst Lmt 
Alarm Reset Counter [ms]  WBFS Alarm Rst Cnt 
Alarm Delay Limit [ms]  WBFS Alarm Dly Lmt 
Alarm Delay Counter [ms]  WBFS Alarm Dly Cnt 
Alarm Status WBFS Status 
 
    
Plot Three 
Parameter Description 
Alarm Source Indicates what triggered the alarm condition; 3-low
 AFR condition, 5-high AFR condition, 3-
auxiliary input, 9-alarm test 
Alarm Status  Indicates state of alarm; 1-alarm trig gered, 0-alarm not triggered 
Alarm Reset Limit  Alarm Reset value 
Alarm Reset 
Counter  Counts up from zero to Alarm Reset value once AFR h
as returned into the acceptable range 
Alarm Delay Limit  Alarm Delay value 
Alarm Delay  
Counter  Counts up from zero to Alarm Delay value when AFR o
ccurs outside the high or low AFR 
limits; once full Alarm Delay value is reached the  alarm will trigger; counter will reset back to 
zero if AFR returns back into the acceptable range  once count up has began  
						

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Output Configuration 
  
The Wideband Failsafe has one ground (low side) output that is triggered when an alarm condition exists.  
This output can be used in a multitude of ways to r educe boost, retard ignition timing, or otherwise protect 
an engine in the event there is a problem with the  fuel system.  The following is an index of possible 
auxiliary devices that can be triggered by the alar m output: 
 
AEM EMS 
Function Description 
Nitrous Fuel & 
Ignition Maps  Use the ground output to trigger the nitrous fuel a
nd ignition maps; ignition timing can be 
reduced and fuel can be added 
Boost Switch  Use the ground output to trigger the b oost switch; a lower boost value can be targeted 
Two-Step  Use the ground output to trigger the two-s tep; a lower engine rev limit can be selected 
 
MSD Ignition Products 
Product Description 
DIS2 (62112) Brown wire: use a relay to apply +12V to trigger ig
nition interrupt 
Blue wire: use a relay to apply +12V to trigger two  step 
Pink wire: use a relay to apply +12V to trigger tim ing retard 
DIS4 (62152) Brown wire: use a relay to apply +12V to trigger ig
nition interrupt 
Blue wire: use a relay to apply +12V to trigger two  step 
Pink wire: use a relay to apply +12V to trigger tim ing retard 
6AL-2 (6421)  Blue wire: use a relay to apply +12V t o trigger two step 
Programmable  
6AL-2 (6530)  Dark blue wire: use a relay to apply +12V to trigge
r launch rev limit 
Light blue wire: use a relay to apply +12V to trigg er burn out rev limit 
Pink wire: use a relay to apply +12V to trigger tim ing retard 
Digital 6 Plus (6520) Blue wire: use a relay to apply +12V to trigger two
 step 
Pink wire: use a relay to apply +12V to trigger tim ing retard 
Start/Retard Control (8982)  Violet wire: use a rela y to apply +12V to trigger timing retard 
Timing Controller (8980)  Grey wire: ground input to  trigger timing retard 
  
Warning Light
 
  
The Wideband Failsafe can also be used to directly  activate a warning light (Autometer PN 3239 or 
similar). Connect the warning light’s white wire to  12V and the low side output to the warning light’s  black 
(ground) wire to turn the light ON. NOTE: High curr ent lights will require a relay to be installed. 
 
   
						

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NC/NO Relay  
  
The following are examples of how a NC/NO relay (Bosch PN 0-332-019-203 or similar) can be 
configured for use with the Wideband Failsafe.    
Signal Interrupt : The low side (ground) output from the W ideband Fa ilsafe can be used to turn ON a NC 
(normally closed) relay and interrupt the output si gnal from a boost controller to its boost solenoid (shown 
below). NOTE: Be sure that pulling power from the b oost solenoid will decrease boost down to the 
wastegate spring pressure rather than increase boos t to the turbochargers max. This will depend on what 
type of wastegate is used and how it is plumbed wit h vacuum hose. 
 
 
Auxiliary Device : The low side (ground) output from the Wideband Fa ilsafe can be used to turn ON a NO 
(normally open) relay and activate or deactivate an  auxiliary device that can be used to reduce timing or 
boost or control some other function when the curre nt requirement is greater than 1.5 amps. 
    
						

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Appendix I - Analog Outputs 
  
There are 2 analog outputs from the Wideband Failsafe; Pressure (MAP) and AFR (O2). These outputs 
are both linear DC voltage signals that vary with P ressure or AFR.  These signals are used for sending  
information to a data logger or an engine managemen t system such as an AEM EMS, AEM F/IC, AEM 
Infinity, etc.  
Pressure Output Transfer Function 
Pressure (psig) = (10 * Volts) – 16 
 
Voltage Pressure (psig) Pressure (Bar) Pressure (kPA) 
0.5  -11  0.25  25 
1.0  -6  0.59  59 
1.5  -1  0.94  94 
2.0  4  1.28  128 
2.5  9  1.63  163 
3.0  14  1.97  197 
3.5  19  2.32  232 
4.0  24  2.66  266 
4.5  29  3.01  301 
   
AFR Output Transfer Function 
AFR (Gas) = (2.375 * Volts) + 7.3125   
Voltage AFR (Gas) AFR (Lambda) 
0.5  8.50  0.58 
1.0  9.69  0.66 
1.5  10.88  0.74 
2.0  12.06  0.82 
2.5  13.25  0.91 
3.0  14.44  0.99 
3.5  15.63  1.07 
4.0  16.81  1.15 
4.5  18.00  1.23 
 
 
 
             
						

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Appendix II - Changing Faceplate / Bezel 
  
The Wideband Failsafe gauge comes with the black bezel and Air/Fuel-Gasoline faceplate installed. 
However, a silver bezel and multiple faceplates are  also included.  To change them, orient the gauge s o 
you are looking at the faceplate.  Rotate the bezel  counter-clockwise to unscrew it from the gauge cup .  
The bezel, lens, and rubber spacer are all removabl e.  Next, remove the faceplate, but note the two 
keyways on each side. W hen inserting the new facepl ate be cognizant of these keyways and line them up 
before reassembling.   
When reassembling the gauge, it may be necessary to  apply a light amount of pressure on the lens and 
spacer to keep the faceplate from rotating when rei nstalling the bezel. Do not over-tighten the bezel 
when reassembling the gauge.  
 
                         
						

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Appendix III - AEMnet 
  
The following instructions describe the proper installation of the optional AEMnet Harness (30-
3439), which is used to connect the W ideband Failsa fe AEMnet communication lines to a second 
(or multiple) AEMnet device(s).    1.  Disconnect the W ideband Failsafe 16-pin harness  connector from the Wideband Failsafe gauge. The 
harness connector has a latch on the bottom side th at needs to be squeezed as the connector is 
lightly freed from the gauge. Refer to Figure 1 bel ow. 
 
 
Figure 1 
 
2.  Locate the green and white pre-crimped terminals  on the end of the AEMnet Harness. Figure 2 below 
shows the W ideband Failsafe connector and pinout in cluding the green and white leads from the 
AEMnet harness.   
 
Figure 2 
 
3.  Before inserting the terminals into the connecto r, refer to Figure 3 to be sure that the locking 
mechanism on the terminals is positioned properly i n the connector. 
 
 
Figure 3 
 
     
						

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4.  Insert the AEMnet+ terminal (white wire) into the available Pin 13 on the W ideband Failsafe 
connector. Push the wire in until the locking mecha nism on the terminal and connector lock into 
place. Pull lightly on the white wire to confirm th e locking mechanism has latched. Figure 4 below 
shows the correct placement of the AEMnet+ terminal . 
 
 
Figure 4 
 
5.  Insert the AEMnet- terminal (green wire) into th e available Pin 12 on the W ideband Failsafe 
connector. Push the wire in until the locking mecha nism on the terminal and connector lock into 
place. Pull lightly on the green wire to confirm th e locking mechanism has latched. Figure 5 below 
shows the correct placement of the AEMnet- terminal . 
 
 
Figure 5 
 
  
6.  Connect the Deutsch connector on the opposite en d of the AEMnet harness to a mating Deutsch 
connector on a second device with AEMnet capabiliti es. The AEMnet harness includes a male and 
female Deutsch connector, allowing AEMnet devices t o be daisy-chained together. 
 
        
    
						

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AEMnet Messages  
Message 
ID: 0x00000026 (29-bit) 
Rate:  10mS continuous 
Byte Label Data Type Scaling Offset Range 
0 Lambda 16 bit unsigned .0001 Lambda/bit 0 0 to 6.5535 Lambda 1 
2 Pressure 16 bit unsigned .001 PSI/bit -15 -15 to 50.535 PSI 3 
4 RPM 16 bit unsigned .39063 RPM/bit 0 0 to 25,600 RPM 5 
6 (bit0)  AFR Ready Boolean 0 = false, 1 = true 0 0/1 
6 (bit1) AFR Heater Open Error Boolean 0 = false, 1 = true 0 0/1 
6 (bit2)  AFR CJ125 Error Boolean 0 = false, 1 = true 0 0/1 
6 (bit3) AFR Sensor Heating Up Boolean 0 = false, 1 = true 0 0/1 
6 (bit4)  AFR Low Voltage Boolean 0 = false, 1 = true 0 0/1 
6 (bit5) AFR Heater Time-Out Error Boolean 0 = false, 1 = true 0 0/1 
6 (bit6)  AFR Heater Short Error Boolean 0 = false, 1 = true 0 0/1 
6 (bit7)  AFR Overtemp Error Boolean 0 = false, 1 = true 0 0/1 
7 (bit0)  Alarm Status Boolean 0 = false, 1 = true 0 0/1 
7 (bit1) Alarm Source Boolean 0 = false, 1 = true 0 0/1 
7 (bit2) Alarm Source Boolean 0 = false, 1 = true 0 0/1 
7 (bit3) Alarm Source Boolean 0 = false, 1 = true 0 0/1 
7 (bit4) --- --- --- --- --- 
7 (bit5) --- --- --- --- --- 
7 (bit6) --- --- --- --- --- 
7 (bit7) --- --- --- --- --- 
      Message 
ID: 0x00000027 (29-bit) 
Rate:  10mS continuous 
Byte Label Data Type Scaling Offset Range 
0 Lambda Upper Limit 16 bit unsigned .0001 Lambda/bit 0 0 to 6.5535 Lambda 1 
2 Lambda Lower Limit 16 bit unsigned .0001 Lambda/bit 0 0 to 6.5535 Lambda 3 
4 Alarm Delay Limit 16 bit unsigned 1 mS/bit 0 0 to 65,535 mS 5 
6 Alarm Delay Counter 16 bit unsigned 1 mS/bit 0 0 to 65,535 mS 7 
      Message 
ID: 0x00000028 (29-bit)  Rate:  10mS while in alarm mode, not transmitted oth erwise 
Byte Label Data Type Scaling Offset Range 
0 Alarm Lambda 16 bit unsigned .0001 Lambda/bit 0 0 to 6.5535 Lambda 1 
2 Alarm Pressure 16 bit unsigned .001 PSI/bit -15 -15 to 50.535 PSI 3 
4 Alarm Reset Limit 16 bit unsigned 1 mS/bit 0 0 to 65,535 mS 5 
6 Alarm Reset Counter 16 bit unsigned 1 mS/bit 0 0 to 65,535 mS 7