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I thought I would put all this info in an area that could be looked up easily. This info is the result of the labor and talent of many people(I can't take credit for ANY of it). Dig,Bill,Leroy,Brian,Barry,Peter....there are just so many. The tables are taken from the Diy EFI WB pages and the TechEdge web pages. Info on prom code modifications and ecm hookups to the Syty's GMP4 ecm are courtesy of many discussions in the forums. This is the DIY-EFI WB table: 4.00 Free Air
The following graph shows the DIY-WB's Vout voltage
against Lambda. The Lambda measure is independant of the hydrocarbon
fuel being used. The stoichiometric point is where all the available
oxygen has combined with all the available fuel leaving no free residual
oxygen. The stoichiometric point is shown on the graph as the vertical
blue line at lambda of 1.00. The stoichiometric output voltage is
nominally 2.50 Volts and this point is shown as the horizontal green
line that crosses the blue line at a lambda of 1.00. This table show the DIY-WB unit's measured Lambda against the Vout voltage which is available at pin 7 of the male DB9 connector (pin 6 = GND). Note that Lambda is a ratio of ratios and is 1.0 exactly at the stoichiometric point for any given fuel. This table shows the approximate AFRs for a number different common fuels. As fuel compositions are seasonal and regional, the AFRs shown here should be considered only as approximate. The free-air Vout point of 4.00 volts is interesting from a number of viewpoints. The free-air voltage will vary a little from location to location as there will be differing trace concentrations of various hydrocarbon fuels in the atmosphere. The free-air point can be used to calibrate the DIY-WB unit for a particular sensor that has aged or is not close enough to 4.00 Volts using the original calibration resistor that is built into the sensor's 8 pin Sumitomo connector. As noted above, the basic WB unit's Vout may vary slightly from the specifications shown here. The stoichiometric Vout of 2.50 may be a little higher or lower (+/- 0.03 Volts) and the free-air Vout may be a little higher or lower than 4.00. It's worth noting that the most important calibration value is to get the difference between the stoic Vout (2.50) and free-air (4.00) to be as close as possible to 1.50 Volts so that the interesting tuning AFR range (AFRs of between 10 and 15 for petrol) are then most accurately represented. When this 1.50 volt specification is achieved, and the unit's offset from the nominal 2.50 volt stoic value is compensated for, quite reliable AFR values can be obtained from the unit. Vout Lambda Petrol LPG Ethanol Diesel As you can see, the charts are nearly identical when comparing the TechEdge to the DIY-EFI. You will connect the "Vout" of the board
to pin F14 on the syty ECM. Use a blade type 5 amp fuse on the +12 volt feed to
the WB controller. Sensor needs to be mounted on TOP of the downpipe as close as practical to the exhaust housing of the turbo. Mounting it on top of the pipe prevents condensation formation from damaging the sensor when the truck is shut off. Use the stock O2 sensor mounting location as a reference to get an idea. Also, make sure you grab a good ground for the controller
on the ECM someplace. Oxygen Sensor Attributes You cannot just cut the plug off of the sensor to run the wiring. There is a calibration resistor in the plug itself. The following is a list of addresses and what to change the contents to in order for the DIY WB sensors to work. This Hack that Dig made actually displays the TRUE air to fuel ratio in the appropriate field in Datamaster or Diacom. This ONLY works with the DIY design WB contollers using the L1H1 WB sensors. Also note that you cannot put the ecm into test mode anymore as this code writes over that area. You dont need to put it into test mode anyway if you are using Promgrammer(thanks Bill) and Datamaster or Diacom anyway. This assumes a starting address of 000000 Hex. 000152:20 Dig was explicit about the use of this code. It is NOT to be used for any purpose of monetary gain whatsoever. This code does NOT make the stock ecm use the Vout of the controller to actually CORRECT the A/F ratio. It merely displays the readings in appropriate reference point in the ALDL serial data. VERY important for tuning.
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