re - tune?
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Road Master
Joined: Aug 2008
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From: illinois
re - tune?
ok my 2012 roadglide custom is stock except it has v& h twin slash slipons. stock air box. when i remove the cat from the headpipe will i need to retune or will the emc be able to adjust for it?
Elite HDF Member
Joined: May 2008
Posts: 3,875
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From: Bergen, Norway
Interesting tread. I have headers with cat in, sest, air and have had it dynoed. Wonder if I have to retune after install with vance & hines power duals? Sorry not trying to hi jack tread, just an interesting case :-)
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Club Member
Joined: Feb 2007
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My understanding is that the adjustments are minor within a range. If you have a VE cell that is 97 at 2500 rpm and 20% throttle position the max adjustment is 10-15% of 97. For this discussion - the 97 is hardcoded into the cell and cannot be changed. Changes for the 10-15% happen in the adaptive fuel table which is the overall average of what is needed based on o2 feedback.
So for math purpose, lets use 15%. This will give you a variance of about 14.5 (97 plus/minus 14.5). If the cell needs 120 instead of 97 to be optimized it will never get there either in the original VE table OR the adaptive table. The adaptive table would have a max of 14.5 that gets added or subtracted.
So long story short - you may get away without doing a tune, but your bike will not necessarily flow through the RPM ranges and throttle positions smoothly. In addition the bike does not adjust well in areas that are being run in open loop which are basically the spaces where you twist the throttle.
So for math purpose, lets use 15%. This will give you a variance of about 14.5 (97 plus/minus 14.5). If the cell needs 120 instead of 97 to be optimized it will never get there either in the original VE table OR the adaptive table. The adaptive table would have a max of 14.5 that gets added or subtracted.
So long story short - you may get away without doing a tune, but your bike will not necessarily flow through the RPM ranges and throttle positions smoothly. In addition the bike does not adjust well in areas that are being run in open loop which are basically the spaces where you twist the throttle.
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Road Master
Joined: Oct 2007
Posts: 915
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From: SE FL & Black Hills SD
So now my question: Would like to get a little more out of the bike, pretty happy with it the way it is. If I do the slip ons and the V&H naked breather conversion, add a Power Comander, will I feel the difference?
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