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Fuel Trim numbers on scan gauge, -40 ? what do they mean ?
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TOPIC: Fuel Trim numbers on scan gauge, -40 ? what do they mean ?

Fuel Trim numbers on scan gauge, -40 ? what do they mean ? 21 Aug 2013 21:54 #1

  • Grant
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  • Visitor
Hi everyone,
I am trying to figure out what my scan gauge is telling me, the manual only has a brief appendix, and does not give the units the fuel trim is measured in !
What are these figures indicating, I have some minus figures, like -40,which stays fairly constant, and one output fluctuates between -3 and plus 3, perhaps the short term trim ?

I want to know what this means before I fit my grooved TB.
It will be nice to post some comparison figures to support the work of everyone elses efforts.

Thanks
Grant

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Fuel Trim numbers on scan gauge, -40 ? what do they mean ? 22 Aug 2013 00:22 #2

  • TacomaKarl
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Hi Grant

If it's a "ScanGuage" it would be in percent, according to this page it can swing +/- 0-99

» Short Term Fuel Trim Bank 1 CANLF Short Term Fuel Trim Bank 1 CANLF | ScanGauge</a> <br /> <br /> On my OBDII scanner it max's out at +/- 25 which would be 100%. A -10 would be a -40%, So a -40 (40%)would be about average on the Long Fuel trim.<br /> <br /> You want to see both readings go more negative but the Long Fuel trim is the one that will show the most change.<br /> <br /> Karl Fortner<br /> Tacoma, Washington </div> </div> </td> </tr> <tr> <td class="kbuttonbar-left"> <p>Please <a class="btn-link" href="/login?return=aHR0cHM6Ly9tZW1iZXJzLmdhZGdldG1hbmdyb292ZS5jb20vZm9ydW1zL2dyb292eS1xdWVzdGlvbnMtYW5kLW90aGVyLXN0dWZmLzMzODktZnVlbC10cmltLW51bWJlcnMtb24tc2Nhbi1nYXVnZS00MC13aGF0LWRvLXRoZXktbWVhbg==" rel="nofollow">Log in</a> to join the conversation.</p><div class="kmessage-editmarkup-cover hidden-phone"> </div> <div class="kmessage-buttons-cover"> <div class="kmessage-buttons-row"> </div> </div> </td> </tr> </tbody> </table> </div> </div> <div class="kcontainer"> <div class="kbody"> <div class="kmsg-header kmsg-header-left"> <h2> <span class="kmsgtitle kmsg-title-left"> Fuel Trim numbers on scan gauge, -40 ? what do they mean ? </span> <span class="kmsgdate kmsgdate-left" title="29 Aug 2013 20:05"> 29 Aug 2013 20:05 </span> <span class="kmsg-id-left"> <a href="#4342" id="4342" rel="canonical">#3</a> </span> </h2> </div> <table class="kmsg kpublished"> <tbody> <tr> <td class="kprofile-left" rowspan="2"> <ul class="kpost-profile"> <li class="kpost-username"> <strong><span class="kwho-guest hasTooltip">Grant</span></strong> </li> <li> Visitor </li> <li> <img src="/media/kunena/ranks/rank0.gif" height="16" width="70" alt="Visitor" /> </li> </td> <td class="kmessage-left"> <div class="kmsgbody"> <div class="kmsgtex"> Hi Karl,<br /> I think my long term went from -30 something to -40, -41<br /> <br /> I'm not sure how fuel trim equates to economy, but this is obviously an improvement.<br /> <br /> Thanks<br /> Grant </div> </div> </td> </tr> <tr> <td class="kbuttonbar-left"> <p>Please <a class="btn-link" href="/login?return=aHR0cHM6Ly9tZW1iZXJzLmdhZGdldG1hbmdyb292ZS5jb20vZm9ydW1zL2dyb292eS1xdWVzdGlvbnMtYW5kLW90aGVyLXN0dWZmLzMzODktZnVlbC10cmltLW51bWJlcnMtb24tc2Nhbi1nYXVnZS00MC13aGF0LWRvLXRoZXktbWVhbg==" rel="nofollow">Log in</a> to join the conversation.</p><div class="kmessage-editmarkup-cover hidden-phone"> </div> <div class="kmessage-buttons-cover"> <div class="kmessage-buttons-row"> </div> </div> </td> </tr> </tbody> </table> </div> </div> <div class="kcontainer"> <div class="kbody"> <div class="kmsg-header kmsg-header-left"> <h2> <span class="kmsgtitle kmsg-title-left"> Fuel Trim numbers on scan gauge, -40 ? what do they mean ? </span> <span class="kmsgdate kmsgdate-left" title="29 Aug 2013 20:44"> 29 Aug 2013 20:44 </span> <span class="kmsg-id-left"> <a href="#4344" id="4344" rel="canonical">#4</a> </span> </h2> </div> <table class="kmsg kpublished"> <tbody> <tr> <td class="kprofile-left" rowspan="2"> <ul class="kpost-profile"> <li class="kpost-username"> <strong><span class="kwho-guest hasTooltip">dan</span></strong> </li> <li> Visitor </li> <li> <img src="/media/kunena/ranks/rank0.gif" height="16" width="70" alt="Visitor" /> </li> </td> <td class="kmessage-left"> <div class="kmsgbody"> <div class="kmsgtex"> On a a scanner obd 2 the ecu always trys to go to 0 which is 14.7 to 1 fuel ratio to determine how much fuel you add or take away is where the % neg or pos comes in.<br /> <br /> you add the long and short numbers to determine how much raw fuel is added or taken away from injectors,neg is taking away pos is adding fuel Most ecus will only allow 50%max before light or limp mode Dan Merrick </div> </div> </td> </tr> <tr> <td class="kbuttonbar-left"> <p>Please <a class="btn-link" href="/login?return=aHR0cHM6Ly9tZW1iZXJzLmdhZGdldG1hbmdyb292ZS5jb20vZm9ydW1zL2dyb292eS1xdWVzdGlvbnMtYW5kLW90aGVyLXN0dWZmLzMzODktZnVlbC10cmltLW51bWJlcnMtb24tc2Nhbi1nYXVnZS00MC13aGF0LWRvLXRoZXktbWVhbg==" rel="nofollow">Log in</a> to join the conversation.</p><div class="kmessage-editmarkup-cover hidden-phone"> </div> <div class="kmessage-buttons-cover"> <div class="kmessage-buttons-row"> </div> </div> </td> </tr> </tbody> </table> </div> </div> <div class="kcontainer"> <div class="kbody"> <div class="kmsg-header kmsg-header-left"> <h2> <span class="kmsgtitle kmsg-title-left"> Fuel Trim numbers on scan gauge, -40 ? what do they mean ? </span> <span class="kmsgdate kmsgdate-left" title="29 Aug 2013 20:52"> 29 Aug 2013 20:52 </span> <span class="kmsg-id-left"> <a href="#4345" id="4345" rel="canonical">#5</a> </span> </h2> </div> <table class="kmsg kpublished"> <tbody> <tr> <td class="kprofile-left" rowspan="2"> <ul class="kpost-profile"> <li class="kpost-username"> <strong><span class="kwho-guest hasTooltip">Grant</span></strong> </li> <li> Visitor </li> <li> <img src="/media/kunena/ranks/rank0.gif" height="16" width="70" alt="Visitor" /> </li> </td> <td class="kmessage-left"> <div class="kmsgbody"> <div class="kmsgtex"> Hi Dan,<br /> My scan gauge displays 4 fuel trim numbers at once. One number is a constant -42, one fluctuates between -35 to -42, the third one is fluctuating between +3 to -3.<br /> I didn't know enough about my gauge before I fitted the grooved TB to get a good before and after comparison. I may be able to download data from it to my PC, I will have to look into that.<br /> <br /> Grant </div> </div> </td> </tr> <tr> <td class="kbuttonbar-left"> <p>Please <a class="btn-link" href="/login?return=aHR0cHM6Ly9tZW1iZXJzLmdhZGdldG1hbmdyb292ZS5jb20vZm9ydW1zL2dyb292eS1xdWVzdGlvbnMtYW5kLW90aGVyLXN0dWZmLzMzODktZnVlbC10cmltLW51bWJlcnMtb24tc2Nhbi1nYXVnZS00MC13aGF0LWRvLXRoZXktbWVhbg==" rel="nofollow">Log in</a> to join the conversation.</p><div class="kmessage-editmarkup-cover hidden-phone"> </div> <div class="kmessage-buttons-cover"> <div class="kmessage-buttons-row"> </div> </div> </td> </tr> </tbody> </table> </div> </div> <div class="kcontainer"> <div class="kbody"> <div class="kmsg-header kmsg-header-left"> <h2> <span class="kmsgtitle kmsg-title-left"> Fuel Trim numbers on scan gauge, -40 ? what do they mean ? </span> <span class="kmsgdate kmsgdate-left" title="31 Aug 2013 22:27"> 31 Aug 2013 22:27 </span> <span class="kmsg-id-left"> <a href="#4356" id="4356" rel="canonical">#6</a> </span> </h2> </div> <table class="kmsg kpublished"> <tbody> <tr> <td class="kprofile-left" rowspan="2"> <ul class="kpost-profile"> <li class="kpost-username"> <strong><span class="kwho-guest hasTooltip">dan</span></strong> </li> <li> Visitor </li> <li> <img src="/media/kunena/ranks/rank0.gif" height="16" width="70" alt="Visitor" /> </li> </td> <td class="kmessage-left"> <div class="kmsgbody"> <div class="kmsgtex"> You must be using Turbo gauge from China it seems to work well and will record for future results.<br /> <br /> The 4 in 1 gauge. It will let you read real time as well. Study the small books that it came with as it will help alot. </div> </div> </td> </tr> <tr> <td class="kbuttonbar-left"> <p>Please <a class="btn-link" href="/login?return=aHR0cHM6Ly9tZW1iZXJzLmdhZGdldG1hbmdyb292ZS5jb20vZm9ydW1zL2dyb292eS1xdWVzdGlvbnMtYW5kLW90aGVyLXN0dWZmLzMzODktZnVlbC10cmltLW51bWJlcnMtb24tc2Nhbi1nYXVnZS00MC13aGF0LWRvLXRoZXktbWVhbg==" rel="nofollow">Log in</a> to join the conversation.</p><div class="kmessage-editmarkup-cover hidden-phone"> </div> <div class="kmessage-buttons-cover"> <div class="kmessage-buttons-row"> </div> </div> </td> </tr> </tbody> </table> </div> </div> <div class="kcontainer"> <div class="kbody"> <div class="kmsg-header kmsg-header-left"> <h2> <span class="kmsgtitle kmsg-title-left"> Fuel Trim numbers on scan gauge, -40 ? what do they mean ? </span> <span class="kmsgdate kmsgdate-left" title="01 Sep 2013 18:53"> 01 Sep 2013 18:53 </span> <span class="kmsg-id-left"> <a href="#4362" id="4362" rel="canonical">#7</a> </span> </h2> </div> <table class="kmsg kpublished"> <tbody> <tr> <td class="kprofile-left" rowspan="2"> <ul class="kpost-profile"> <li class="kpost-username"> <strong><span class="kwho-guest hasTooltip">Grant</span></strong> </li> <li> Visitor </li> <li> <img src="/media/kunena/ranks/rank0.gif" height="16" width="70" alt="Visitor" /> </li> </td> <td class="kmessage-left"> <div class="kmsgbody"> <div class="kmsgtex"> Hi Dan,<br /> yes I figured out the real time display mode,<br /> it is the Turbo Gauge, it's very good value for money.<br /> <br /> Grant </div> </div> </td> </tr> <tr> <td class="kbuttonbar-left"> <p>Please <a class="btn-link" href="/login?return=aHR0cHM6Ly9tZW1iZXJzLmdhZGdldG1hbmdyb292ZS5jb20vZm9ydW1zL2dyb292eS1xdWVzdGlvbnMtYW5kLW90aGVyLXN0dWZmLzMzODktZnVlbC10cmltLW51bWJlcnMtb24tc2Nhbi1nYXVnZS00MC13aGF0LWRvLXRoZXktbWVhbg==" rel="nofollow">Log in</a> to join the conversation.</p><div class="kmessage-editmarkup-cover hidden-phone"> </div> <div class="kmessage-buttons-cover"> <div class="kmessage-buttons-row"> </div> </div> </td> </tr> </tbody> </table> </div> </div> </div> <div class="ktopactions"> <table id="topic-actions"> <tbody> <tr> <td class="klist-actions-goto"> <a id="forumtop"> </a> <a href="#forumbottom"> <span class="kicon kforumtop"></span> </a></td> <td class="klist-actions-forum"> <div class="kmessage-buttons-row"> </div> <div class="kmessage-buttons-row"> </div> </td> <td class="klist-pages-all"> <ul class="kpagination"> <li class="page">Page:</li><li><span class="pagenav">1</span></li></ul> </td> </tr> </tbody> </table> </div> <form action="/forums" id="jumpto" name="jumpto" method="post" target="_self"> <input type="hidden" name="view" value="category"/> <input type="hidden" name="task" value="jump"/> <span class="kright"><select name="catid" id="catid" class="inputbox fbs" size="1" onchange = "this.form.submit()"><option value="0">Board Categories</option> <option value="1" selected="selected"> Main Forum</option> <option value="4">- Automotive</option> <option value="5">- - Ford</option> <option value="6">- - General Motors</option> <option value="7">- - Dodge</option> <option value="8">- - Foreign Manufactured</option> <option value="19">- - Performance and Mileage Reports</option> <option value="11">- - Carbureted Vehicles</option> <option value="2">- Welcome Mat</option> <option value="12">- Personal License Pilot Program</option> <option value="9">- Off-Road Applications</option> <option value="10">- Service Bulletins</option> <option value="14">- Brotherly Love</option> <option value="15">- Other Stuff</option> <option value="20">- - Groovy Questions and Other Stuff</option> <option value="22">- - Trial and Error-How we learn!</option> <option value="16">- Diagnostics</option> <option value="17">- Tools of The Trade</option> <option value="25">- Open Discussions</option> </select></span> </form> <div class="pull-right"></div> <div class="clearfix"></div> <div class="kblock kpathway breadcrumbs-2"> <div class="kcontainer"> <div class="ksectionbody"> <div class = "kforum-pathway"> <div class="path-element-first"><a href="index.php?option=com_kunena&view=home&defaultmenu=2413&Itemid=2408">Forums</a></div> <div class="path-element"><a href="index.php?option=com_kunena&view=category&catid=1&Itemid=2408">Main Forum</a></div> <div class="path-element"><a href="index.php?option=com_kunena&view=category&catid=15&Itemid=2408">Other Stuff</a></div> <div class="path-element"><a href="index.php?option=com_kunena&view=category&catid=20&Itemid=2408">Groovy Questions and Other Stuff</a></div> <div class="path-element"><a href="index.php?option=com_kunena&view=topic&catid=20&id=3389&Itemid=2408">Fuel Trim numbers on scan gauge, -40 ? 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