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<h1>SD VE Adjust (SDRatio)</h1> <div class="level1"> <p> First and foremost, let's make it clear what this page is all about. This page describes an adjustment tool in the ECMLink application that helps to dial in your speed density (SD) VE table based on data collected from a mass airflow sensor. If you do not plan to run speed density mode with your car or you do plan to run SD but do not have a mass airflow sensor installed for dial-in, then this page is completely useless to you and you should ignore it. </p> <p> If you're not even sure what speed density mode means, then read up on our <a href="/wiki/doku.php?id=sd101" class="wikilink1" title="sd101">Speed Density 101</a> page. </p> <p> The following assumes that you have already configured your ECU and installed the sensors for speed density operation. If you have not, please read our <a href="/wiki/doku.php?id=sdsetup" class="wikilink1" title="sdsetup">ECMLink - Speed Density Setup</a> page. In particular, you must have your manifold absolute pressure (MAP) sensor installed and configured in the ECU Inputs tab of the ECMLink application. And you must have the intake air temp sensor installed and connected to the intake air temp input of the ECU (IAT sensor exception listed below in the NOTES section related to using a stock mass airflow sensor). </p> </div> <h1>STEP 1: Mass Airflow Sensor Calibration</h1> <div class="level1"> <p> This function basically tries to configure your SD table to produce the same airflow values as your mass airflow sensor. So it stands to reason that you want to make sure your mass airflow sensor is calibrated very well first. </p> <p> The <a href="/wiki/doku.php?id=v3mafadjcombft" class="wikilink1" title="v3mafadjcombft">MAFComp Adjust (CombinedFT)</a> page describes an excellent process for dialing in your mass airflow sensor. Please read through this page carefully and make sure your mass airflow setup is calibrated as well as you can get it before attempting to use the <b>SD VE Adjust (SDRatio)</b> function. </p> </div> <h1>STEP 2: Data Capture</h1> <div class="level1"> <p> To use this tool, you need to capture some data from your ECU while you drive around on the mass airflow sensor. </p> <p> <a href="/wiki/lib/exe/fetch.php?tok=c72986&media=http%3A%2F%2Fwww.ecmtuning.com%2Fimages%2Fforums%2Fsddata%2Fsdmaploc.png" class="media" title="http://www.ecmtuning.com/images/forums/sddata/sdmaploc.png"><img src="/wiki/lib/exe/fetch.php?tok=c72986&media=http%3A%2F%2Fwww.ecmtuning.com%2Fimages%2Fforums%2Fsddata%2Fsdmaploc.png" class="mediaright" alt="" /></a> Add the following log items to your captured values (F10): SDRatio and MAP sensor </p> <p> The MAP sensor you want to log here is the one you have already configured in your <b>Manifold pressure (MAP)</b> field on the ECU Input tabs. An example of this is shown here. More details on configuring and installing this sensor can be found on the <a href="/wiki/doku.php?id=sdsetup" class="wikilink1" title="sdsetup">ECMLink - Speed Density Setup</a> page. </p> <p> When attempting to initialize the <b>SD VE Adjust (SDRatio)</b> tool, the application will check your ECU Input tab to locate the MAP sensor. It will then attempt to find this sensor in your datalog. Using the image above as an example, you would want to log the GM 3-bar sensor attached to the MDP input in order to use this function. </p> </div> <h1>STEP 3: Drive Around on the Mass Airflow Sensor</h1> <div class="level1"> <p> That's literally it. While running off the mass airflow sensor, you basically just drive around logging the data above (SDRatio and MAP sensor) in your datalog. Try to drive under a variety of conditions (idle, cruise, wide open throttle). I like to locate a nice hilly area so I can vary throttle position, RPM and boost to generate the data I'm looking for. </p> <p> When you're done, you right click in the graph area and select the <b>SD VE Adjust (SDRatio)</b> menu item. The application will then make a number of suggested changes to your SD VE table. You will definitely want to smooth and tweak this data a bit to make it "look nice". The application is just going to slap numbers into cells that it has data for. You'll need to extrapolate that data a bit to areas where you don't normally drive if you want to make the table work well in unexpected conditions. </p> </div> <h1>NOTES: Things to Keep in Mind</h1> <div class="level1"> </div> <h2>Airflow Smoothing</h2> <div class="level2"> <p> When switching back and forth between speed density operation and mass airflow sensor operation, it's VERY easy to forget to configure the airflow smoothing table appropriately. Try to keep this in mind. When running speed density, you want to configure this table to be all zero (or very nearly so) as explained on the <a href="/wiki/doku.php?id=sdsetup" class="wikilink1" title="sdsetup">ECMLink - Speed Density Setup</a> page. But when you want to switch back to a mass airflow sensor, you need to remember to switch the airflow smoothing back to match. You can do this easily by opening a log file you created while running on the mass airflow sensor before and pulling up its embedded direct access data (F8). Then you can simply pull up the airflow smoothing tab and hit "Copy to ECU". </p> </div> <h2>Stock (Mitsubishi) MAF sensor</h2> <div class="level2"> <p> Running on a stock Mitsubishi MAF sensor is a great idea for dialing in SD because it tends to produce a very accurate signal. However, the problem is that a stock sensor uses the intake air temp input to the ECU for its own purpose. You can not simply disconnect this and connect your own GM IAT sensor. Your airflow readings WILL be off. </p> <p> In order to use a stock MAF sensor in conjunction with the <b>SD VE Adjust (SDRatio)</b> tool, you must basically disable speed density's use of the air temperature sensor for airflow calculation. You do that by setting the entire <b>SDTempWeighting</b> table (found on the Direct Access tab) to zero across the board. If you do not do this, the ECU will try to treat the factory MAF sensor's air temperature reading as a GM IAT sensor located in the upper IC (or intake manifold). The results will be an inaccurate calculation of the SDRatio value and inaccurate adjustments to your SD VE table. </p> <p> The downside, of course, is that if you disable the air temp sensor for speed density operation inside the ECU, then you need to make sure your air temperature reading while doing your calibration drive doesn't vary too much. A good working intercooler and some careful attention to your right foot will help immensely with this. </p> </div>