renaldo99 Posted November 5, 2010 Report Share Posted November 5, 2010 (edited) i got the 4.10s installed, it seems to drive fine and it chirps 2nd gear but when i let off the gas at about 50mph and it feels like something is gonna break in the trans or rear end, like it down shifts really bad an the whole truck shakes... is this cause it hasnt been tuned for the new gears? Edited November 5, 2010 by SuperchargedTahoeSS (see edit history) Quote Link to comment Share on other sites More sharing options...
blackbeast ss Posted November 5, 2010 Report Share Posted November 5, 2010 no thats not normal!!! who installed your gears?? Quote Link to comment Share on other sites More sharing options...
renaldo99 Posted November 5, 2010 Author Report Share Posted November 5, 2010 no thats not normal!!! who installed your gears?? My mechanic Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted November 5, 2010 Report Share Posted November 5, 2010 Yes you need to adjust your tune for the new rear ratio...... Quote Link to comment Share on other sites More sharing options...
renaldo99 Posted November 5, 2010 Author Report Share Posted November 5, 2010 Yes you need to adjust your tune for the new rear ratio...... so thats why its doing that ? Quote Link to comment Share on other sites More sharing options...
BlueAKSSS Posted November 5, 2010 Report Share Posted November 5, 2010 so thats why its doing that ? The problem you described does not sound like a problem with the tune, the tune will just fix the speedo being off from the gear chance and other ratios I would assume. Take it back to your mechanic and tell him what's going on. Quote Link to comment Share on other sites More sharing options...
misterp Posted November 5, 2010 Report Share Posted November 5, 2010 i got the 4.10s installed, it seems to drive fine and it chirps 2nd gear but when i let off the gas at about 50mph and it feels like something is gonna break in the trans or rear end, like it down shifts really bad an the whole truck shakes... is this cause it hasnt been tuned for the new gears? Are you saying that when you let off the throttle in WOT 2nd gear it immediately downshifts back into 1st gear? If so then yes the issue is that the tune (transmission shift speeds) are off. You must do a PCM adjustment after installing new gears, just like you need a new re-tune after installing smaller diameter tires - same exact deal. The speedometer will be off, the shift points will be off, the MPH fuel cutoff (limiter) will be off... PLUS to be honest the actual engine calibration could use a re-visit as well, the AFR will not change but the ignition spark timing tables could probably be optimized a tad for the new gearing = better launches and part-throttle driving. Mr. P. Quote Link to comment Share on other sites More sharing options...
renaldo99 Posted November 5, 2010 Author Report Share Posted November 5, 2010 Are you saying that when you let off the throttle in WOT 2nd gear it immediately downshifts back into 1st gear? If so then yes the issue is that the tune (transmission shift speeds) are off. You must do a PCM adjustment after installing new gears, just like you need a new re-tune after installing smaller diameter tires - same exact deal. The speedometer will be off, the shift points will be off, the MPH fuel cutoff (limiter) will be off... PLUS to be honest the actual engine calibration could use a re-visit as well, the AFR will not change but the ignition spark timing tables could probably be optimized a tad for the new gearing = better launches and part-throttle driving. Mr. P. No thats not what i mean it goes to 4th gear at 45-50 and it down shifts weird.. but I took it to a new tuner and he was saying the converter is locking up thats why its acting weird, so i gotta get it retuned and the stall is too high for my setup but he can work with it... Hes been doing this for over 20years so i trust him Quote Link to comment Share on other sites More sharing options...
renaldo99 Posted November 5, 2010 Author Report Share Posted November 5, 2010 ok so i just ran my jet chip programmer 4 on my pcm and changed the tire size and the gear ratio but nothing else. My truck seems to drive fine now so idk if i should get it retuned lol Quote Link to comment Share on other sites More sharing options...
misterp Posted November 8, 2010 Report Share Posted November 8, 2010 ok so i just ran my jet chip programmer 4 on my pcm and changed the tire size and the gear ratio but nothing else. My truck seems to drive fine now so idk if i should get it retuned lol Glad you got that squared-away! Air/fuel ratio (wideband) will not change due to change in gearing, but there could be areas in your spark table which could gain some optimizing due to new gearing. But no you don't need to retune if the truck was running fine before the gear swap, you are not going to see any increased risk of going lean or detonation by going to a lower gear ratio. My 2-cents. Mr. P. Quote Link to comment Share on other sites More sharing options...
renaldo99 Posted November 9, 2010 Author Report Share Posted November 9, 2010 Glad you got that squared-away! Air/fuel ratio (wideband) will not change due to change in gearing, but there could be areas in your spark table which could gain some optimizing due to new gearing. But no you don't need to retune if the truck was running fine before the gear swap, you are not going to see any increased risk of going lean or detonation by going to a lower gear ratio. My 2-cents. Mr. P. well i had a big problem with my jet chip programmer, cause as soon as i did the retune which all i did was change the tire size and gear ratio and my truck started driving really bad and the idle was so bad it stalled on me a few times. On my info screen on my speedo it was saying engine reduced power , so i took the jet chip program off and dropped it off at a shop to get retuned and fixed Quote Link to comment Share on other sites More sharing options...
renaldo99 Posted November 12, 2010 Author Report Share Posted November 12, 2010 Got everything fixed and retuned.. Havent really punched it on 2wd, it seems faster but on 4wd its a effin beast! I was testing it out and just punched it at a deadstop and all 4 wheels burned out then it grips after but damn lol Quote Link to comment Share on other sites More sharing options...
misterp Posted November 12, 2010 Report Share Posted November 12, 2010 Freaking awesome! Quote Link to comment Share on other sites More sharing options...
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