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Throttle lag??????

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Old 03-01-2006, 11:18 AM
  #11  
Stooge
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Default RE: Throttle lag??????


ORIGINAL: chevykiller

I have dealt with this issue at length. It is a very common and frustrating problem. I know this is going to sound simple, but I tried EVERYTHING, and I mean everything. From a/f adjustments, to clutch timing, to cam timing, and just about every adjustment you can make in the computer. I could always get the lag between shifts at WOT to shorten, but I could never get it to actual go away. Believe it or not, what solved the problem was a simple matter of setting my rev limiter far beyond my shift points. Turns out that the computer has a sensing program that actually kicks in right before the rev limiter that slightly retards the timing in preperation for the rev limiter function. Try shifting at WOT throttle at 5000 rpm and you won't see the lag. Don't set your rev limiter too crazy cause you don't want to blow your engine if you miss a shift. Try setting it for 7000 rpm and still make your shifts around 6000 (where you probably do now anyway) and see if that removes the lag. Let me know how it works for you.

Edit - this is for WOT shifts. The lag at the beginning of your punch is common in the auto because of the computer taking time to read the throttle before sending the 'okay' for the throttle response. If you are just concerned with the takeoff lag, then simply give the gas slowly unitl the car grabs before you punch it. Once the car has grabbed and you are moving at all - you can slam the pedal down and it will accelerate fine. The autos like to see acceleration first before you punch the pedal...just the way it is with the stock auto. Their are aftermaket torque converters and you can PM spyder for more info as he is very knowledgeable with the auto throttle response..

This is a common problem with the "drive by wire" cars. My Toyota Tundra and Sequoia do the same thing. The solution is, as stated above, give it a little gas before stomping it to let the system "spool -up." All control systems have this lag and you probably cannot tune out this effect (nor, in some instances, would you want to for other reasons). You might find too that you will not get the fastest times, most power with WOT, especially when you whack it open (on motorcycles - it's called "ringing its neck"). You'll probably notice that a gradual "stomp" works better and is in fact faster. Remember, you push the accelerator pedal but the control system opens the throttle plates, much different than the traditional systems.

As a data point, it seems like the "drive by wire" systems on the Toyota V8's are more refined and have less lag. However, you still need to really get used to the pedal feel to really get it to work well. I would have to assume that in later model years, Ford will incorporate faster communications, processing and throttle plate actuators to help eliminate this effect.

I found it amusing that Ford blew a big horn for themselves when they "came up with this revolutionary idea," when it's been used for years by Toyota and Lexus (and probably others). And the Toyota and Lexus systems where designed, from a blank sheet up, right here in the good ole US.
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Old 03-01-2006, 11:45 AM
  #12  
LarryS
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Default RE: Throttle lag??????

Wish one of the manufacturers would come up with a cable that works and get ride of the drive-by-wire. I'm sure we are losing .1 et minimum with this lag at launch.
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Old 03-01-2006, 11:58 AM
  #13  
Stooge
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Default RE: Throttle lag??????


ORIGINAL: LarryS

Wish one of the manufacturers would come up with a cable that works and get ride of the drive-by-wire. I'm sure we are losing .1 et minimum with this lag at launch.

Actually, the drive by wire system makes the operation of the vehicle much more flexible, and possibly safer for the novice driver. With this system, gas mileage and emissions are optimized by the control system, without your input to the pedal, and the traction control system (TCS) can reposition the throttle plates in slippery/low traction conditions without your input. Depending on your perspective, this may or may not be a good thing.

Just with a traction control system (TCS), less advanced cars without "drive by wire" used the ECM to retard engine timing to limit power output of the motor. Vehicles with multichannel anti-lock brake systems could be integrated into the TCS to selectively apply individual wheel brakes in low traction situations (wonder why your lead footed wife or kids wear the rear brakes off her TCS equipped SUV?). Now, with "drive by wire," the TCS can also close the throttle plates, even with you stomping the pedal (WOT), to stop wheel spin. Again, depending on your perspect, could be good, could be bad.
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Old 03-01-2006, 12:09 PM
  #14  
LarryS
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Default RE: Throttle lag??????


ORIGINAL: Stooge


ORIGINAL: LarryS

Wish one of the manufacturers would come up with a cable that works and get ride of the drive-by-wire. I'm sure we are losing .1 et minimum with this lag at launch.

Actually, the drive by wire system makes the operation of the vehicle much more flexible, and possibly safer for the novice driver. With this system, gas mileage and emissions are optimized by the control system, without your input to the pedal, and the traction control system (TCS) can reposition the throttle plates in slippery/low traction conditions without your input. Depending on your perspective, this may or may not be a good thing.

Just with a traction control system (TCS), less advanced cars without "drive by wire" used the ECM to retard engine timing to limit power output of the motor. Vehicles with multichannel anti-lock brake systems could be integrated into the TCS to selectively apply individual wheel brakes in low traction situations (wonder why your lead footed wife or kids wear the rear brakes off her TCS equipped SUV?). Now, with "drive by wire," the TCS can also close the throttle plates, even with you stomping the pedal (WOT), to stop wheel spin. Again, depending on your perspect, could be good, could be bad.
No doubt it's a geat system but just not great for a racer. Just like TCS is not good for a racer.
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Old 03-01-2006, 02:22 PM
  #15  
Speedeamon
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Default RE: Throttle lag??????

could you please help me with this if its not too much hasle and soo that i dont brake my engine. Ok i have an sctxcal 2 so can you guide me through the steps to do what you said please from the sctxcal menu. I am soo sorry for this hasle but you see bieng in the middle east its really reallly hard actually impossible to find someone to do a tune for you a good tune or to even edit setting in sctxcal2. So please if you can guide me step by step i would greatly appriciate it or anyone else.
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Old 03-01-2006, 02:34 PM
  #16  
LarryS
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Default RE: Throttle lag??????

Best to call SCT, tell them your modifications with what you want changed and let them email you a bin file. 407 774 2447
ORIGINAL: Speedeamon

could you please help me with this if its not too much hasle and soo that i dont brake my engine. Ok i have an sctxcal 2 so can you guide me through the steps to do what you said please from the sctxcal menu. I am soo sorry for this hasle but you see bieng in the middle east its really reallly hard actually impossible to find someone to do a tune for you a good tune or to even edit setting in sctxcal2. So please if you can guide me step by step i would greatly appriciate it or anyone else.
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Old 03-01-2006, 03:35 PM
  #17  
Speedeamon
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Default RE: Throttle lag??????

Thanks larry
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