pdd

iTrader: (3)

do you need to get retuned?

Phil99vette

iTrader: (11)

No....

Ferocity02

iTrader: (60)

StxVenomz28

iTrader: (1)

Nope, but it never hurts.

Redneck Z

iTrader: (3)

QUOTE: Nope, but it never hurts.

It could hurt your pocketbook though. I don't see how a tune would help at all.

Sport Side

iTrader: (6)

You'll need to dial in your A/F ratio once again.

StxVenomz28

iTrader: (1)

i still have yet to get mine tuned from stock so for me it would make sense, depends on the situation

Redneck Z

iTrader: (3)

QUOTE: You'll need to dial in your A/F ratio once again.

I didn't think a pulley would effect your tune that much. What does it do that throws off your air/fuel ratio?

EATAZ06MMM

The only thing I've heard is that it might drop your idle to low. In most models, that means hooking up the tuner and resetting the idle. I would think you could get that done without paying for a full tune.

pdd

iTrader: (3)

i luv that name you got

rush7

iTrader: (2)

Well here's my story. I had run autotap after putting on my ls6 intake and then breaking it in for awhile, and my fuel trims were terrible. This was with my old crank pulley. The deceleration fuel trim was the worst with the long term at +25 and the short trim peaking out about +23.6 or something along those lines. But I generally hovered around +18 LTFT and STFT's were almost always positive numbers that frequently hit double digits. I had logged that on two different nights and got about the same shitty trim numbers.

So fast forward to the time after my underdrive pulley install a couple weeks ago: I let the mod break itself in (a trip to Topeka and back so my trims would adjust themselves) checked the trim numbers again with the autotap software and this time the numbers were much closer to zero as the long trims hovered around +6 to +8 and the short trims hovered around zero. I also noticed significantly less fuel consumption in the first full tank of gas as my MPG went from about 15.5 to 20.0 with this mod, and I actually did more city driving on the tank of gas with the pulley. This is only my first tank, but I'm beginning to love this mod for this reason as well.

I'm not completely sold on the notion that the pulley won't affect the tune. I realize the tune will jump some from day to day, but the fuel trims have remained in their lower state since the pulley install and this leads me to believe that the pulley can and very well change your tune.

99blancoSS

iTrader: (115)

Interesting, the better gas mileage should be seen and is accounted for - Your taking parasitic loss off the crank itself with the pulley. As far as effecting the tuning of the car itself it seems like a questionable type of thing either way. If it now takes less gas to move the same distance is the tune really effected in a negative maner that requires re-programming to fix?

technical

Technically speaking the pulley would change the effective overall load on the engine. Depending on where your tune is and the rest of the mods, you could be on the cusp of needing a tune. If your car is bone stock..no tune required. If your car has some mods, especially a cam, then your tune might need to be altered/touched up based on how good your tune is currently dialed in.