Does tire height affect tune?
05-02-2007, 02:14 PM
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Does tire height affect tune? I have a 06 tbss and having a slight issue...If I try to use my drag radials 275-45-17 (m/t) the truck seems to go in a limp mode and I get a code p001 (fuel circut open?) If I have the stock 20's I dont have any issues. The truck has locked tune and was told the tune would be fine but there seems to be a problem. Does any know what the difference in tire height would change? I was thinkin transmission shift points and possible some fueling but I am not sure. Thanks for any help
05-03-2007, 01:54 PM
#4
i think it might. i was running 215/40/18 fronts and 245/35/20 backs and i changed the tire size to that of the 20's.
i think i might be tuning the incorrect cells due to tire size. when i logged fuel trim cell, it would be off from what the rpm/map ve cell i thought it should have been correlated with.
same with the spark, the cell that i thought i should be tuning would not have the the advance showing on the scan.
last night i went to the track and had 215/40/18 fronts and 255/40/18 backs and changed the tire size to that of the backs and my shifts felt weaker and and the last gear wasn't feeling right. my trap was 102 mph vs when i had the 20's on the back it would trap 105mph.
could be a trans issue or something else but i'm leaning towards the tire size changing the tune.
i think i might be tuning the incorrect cells due to tire size. when i logged fuel trim cell, it would be off from what the rpm/map ve cell i thought it should have been correlated with.
same with the spark, the cell that i thought i should be tuning would not have the the advance showing on the scan.
last night i went to the track and had 215/40/18 fronts and 255/40/18 backs and changed the tire size to that of the backs and my shifts felt weaker and and the last gear wasn't feeling right. my trap was 102 mph vs when i had the 20's on the back it would trap 105mph.
could be a trans issue or something else but i'm leaning towards the tire size changing the tune.
05-03-2007, 03:10 PM
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Between the stock size and DR size you posted; there is a 3.3" difference in tire height. So yes, that much of a difference will affect transmission shift points and the speed sensors. I can't seem to pull up that code; can you double check?
BTW - I know most TB SS owners prefer buying canned tunes, but buying a locked tune is not the way to go. I tuned my own and picked up 17awhp across the board and 23 hp in some parts. And that was with 8 degrees of false knock at WOT. Torque was up even more.
BTW - I know most TB SS owners prefer buying canned tunes, but buying a locked tune is not the way to go. I tuned my own and picked up 17awhp across the board and 23 hp in some parts. And that was with 8 degrees of false knock at WOT. Torque was up even more.
05-04-2007, 02:10 PM
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I realize I should have tuned myself but have no clue how to. I did pickup EfiLive scantool just to keep an eye on things but will have to upgrade to start tuning. All I need now are some Cores.
