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Originally Posted by Roush06FX4
Hi,New to forum
...a 2006 Roush stage one supercharged FX4 F-150 supercrew.First of all, the vehicle came with different shocks rather than the listed bilsteins advertised with the 2/3 drop kit...PCM was flashed to a 3.55 gear ratio at 675 revs,Roush had mounted 20"inch BF Goodrich champion baja tires to their rims.The Powertrain Control Module was not recalibrated for these tires which should be calibrated at 644 revs.My vehicle has a 3.73 rear end.Unfortunately my F150 was shifting at 4250 rpm,which is low.A phone call to a Roush revealed,when the dealership sent back the PCM for reflashing,Roush only changes the parameters for the supercharger,a/f and spark.Why is that?They changed the rim and tire size,from the original stock size.Roush also said my truck should shift from 1-2 at 4900 rpm.A trip back to the dealership only confirmed they couldn't reflash the PCM,and they would have to send it back to Roush for recalibration.Does anyone know of an aftermarket tuner or chip I could use for my vehicle??I would like to remove the speed limiter and change the shift points,etc.Any help would be greatly appreciated, thankyou.Im not knocking ROUSH but when you pay for performance,you should be treated accordingly.
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1st, I don't think a Stage 1 anything gets any suspension parts replaced. To my knowledge, only Stage 2 get suspension.
Yes the 20s are 644 rev/mile. But the engine calibration from Ford and also from Roush has a low limit of 650 revs/mile. So 644 cannot be entered.
644 x 3.73= 2402. 675 x 3.55 = 2396. So the # you see is extremely close to the actual # and the PCM will accept both 675 and 3.55, so the speedo is right and the PCM is happy at the same time... the best of both worlds.
Roush changes the whole PCM calibration... all of it. The transmission is reprogrammed also. But Roush chose not to increase the factory shift rpm for whatever reason they though was important enough to keep it that way (warranty???). Yes the engine can make more power with more rpm available.
Speed limiter = Liability. Roush never claimed to remove it anyway.
With the Roush kit, you pay for performance AND a Warranty. Yes there is more performance to be had, if reliability is not important.