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SVTPerformance's Chain of Restaurants
Tuning À la carte
Dies on Return to Idle
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<blockquote data-quote="decipha" data-source="post: 15740590" data-attributes="member: 74327"><p>it sounds like all of yall's issues can be fixed with tuning dashpot</p><p></p><p>first, as the write up says</p><p></p><p>"Dashpot relies on the idle airflow modeling to be accurate, thus any dashpot tuning must be done AFTER <a href="http://www.efidynotuning.com/idleair.htm" target="_blank"><u>Idle Air</u></a> is dialed in, which must be done after <a href="http://www.efidynotuning.com/fuel.htm" target="_blank"><u>Idle Fuel</u></a> is dialed in "</p><p></p><p>make sure your good there first and at idle the iscdty is not stupid high, anything 35% and less is fine, if its higher than that you need to open the throttle stop to give it more air to idle correctly, some cobras specifically the 96-98s will develop a surge below 45% iscdty at idle, I think its something to do with the intake harmonics that causes it but I've witnessed it on numerous occasions</p><p></p><p>anywho, make sure IPSIBR (idle airmass correction) is near 0 at a warm stable idle, if its not dial in your idle air</p><p></p><p>Now to do a quick dashpot adjustment, for simplicity, go set FN882A the maximum dashpot clip to all 2.3s for all rpms, that way dashpot isn't clipped by rpm</p><p></p><p>make sure the DASPTK scalar is maxed out to 0.062, that's the maximum dashpot clip based on relative throttle position</p><p></p><p>DASCTL is a huge scalar, it is the maximum amount of dashpot for idle feedback to be permitted, this should be set high enough that you have quite a bit of dashpot left for idle to stabilize before it completely expires, a value of 0.35 is a good value for this for 4v engines, make sure this isn't set too high though, anything in the 0.60 to 0.80 range can cause a hard start stall in some ecu strategies as it freaks out</p><p></p><p>MINMPH is the minimum mph scalar that idle feedback is allowed to run, on the 03-04 cobras they are very very very air sensitive down low and on decel, in a stock 03/04 cobra tune they are around 25mph, that's a good value for this scalar on those engines</p><p></p><p>now the biggest function for dashpot is the decay rate function, you want it to decay at a controlled and steady rate but not too fast, and not too slow, ideally too slow is less problematic than too fast, I often have the decay slow up top to stabilize the engine first, fast in the mid, and very slow down low, something like this for example</p><p></p><p>16.00 0.0100</p><p>1.500 0.0100 </p><p>0.750 0.0400</p><p>0.500 0.0050</p><p>0.400 0.0020</p><p>0.350 0.0007</p><p>0.000 0.0007</p><p>0.000 0.0007</p><p>0.000 0.0007</p><p></p><p>for a perfect dashpot decay, you want it to hang about 300-500 rpm above idle for just a second then decay down, if the rpm's fall too low and then have to come back up that means you have it decaying too fast, the decay should always catch the rpm in that +300-500 rpm range and bring it down to idle slowly there after</p><p></p><p>also you should set the decay very slowly at and below the dasctl value since its in idle feedback control so decel to idle spark control can stabilize slowly and smooth</p></blockquote><p></p>
[QUOTE="decipha, post: 15740590, member: 74327"] it sounds like all of yall's issues can be fixed with tuning dashpot first, as the write up says "Dashpot relies on the idle airflow modeling to be accurate, thus any dashpot tuning must be done AFTER [URL='http://www.efidynotuning.com/idleair.htm'][U]Idle Air[/U][/URL] is dialed in, which must be done after [URL='http://www.efidynotuning.com/fuel.htm'][U]Idle Fuel[/U][/URL] is dialed in " make sure your good there first and at idle the iscdty is not stupid high, anything 35% and less is fine, if its higher than that you need to open the throttle stop to give it more air to idle correctly, some cobras specifically the 96-98s will develop a surge below 45% iscdty at idle, I think its something to do with the intake harmonics that causes it but I've witnessed it on numerous occasions anywho, make sure IPSIBR (idle airmass correction) is near 0 at a warm stable idle, if its not dial in your idle air Now to do a quick dashpot adjustment, for simplicity, go set FN882A the maximum dashpot clip to all 2.3s for all rpms, that way dashpot isn't clipped by rpm make sure the DASPTK scalar is maxed out to 0.062, that's the maximum dashpot clip based on relative throttle position DASCTL is a huge scalar, it is the maximum amount of dashpot for idle feedback to be permitted, this should be set high enough that you have quite a bit of dashpot left for idle to stabilize before it completely expires, a value of 0.35 is a good value for this for 4v engines, make sure this isn't set too high though, anything in the 0.60 to 0.80 range can cause a hard start stall in some ecu strategies as it freaks out MINMPH is the minimum mph scalar that idle feedback is allowed to run, on the 03-04 cobras they are very very very air sensitive down low and on decel, in a stock 03/04 cobra tune they are around 25mph, that's a good value for this scalar on those engines now the biggest function for dashpot is the decay rate function, you want it to decay at a controlled and steady rate but not too fast, and not too slow, ideally too slow is less problematic than too fast, I often have the decay slow up top to stabilize the engine first, fast in the mid, and very slow down low, something like this for example 16.00 0.0100 1.500 0.0100 0.750 0.0400 0.500 0.0050 0.400 0.0020 0.350 0.0007 0.000 0.0007 0.000 0.0007 0.000 0.0007 for a perfect dashpot decay, you want it to hang about 300-500 rpm above idle for just a second then decay down, if the rpm's fall too low and then have to come back up that means you have it decaying too fast, the decay should always catch the rpm in that +300-500 rpm range and bring it down to idle slowly there after also you should set the decay very slowly at and below the dasctl value since its in idle feedback control so decel to idle spark control can stabilize slowly and smooth [/QUOTE]
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