





Drive by Wire or Throttle Cable
I have been thinking about this a lot lately. In swapping LS power into whatever car, you have the choice to install a "drive by wire" throttle system or a conventional cable pull throttle body.
Let's discuss and get all the opinions out in one place.
DBW incorperates quite a few functions into one module on the TB that cable TBs dont have and need extra pieces for, like IAC and cruise
My biggest issues with DBW are;
1) fitting the big a$$ pedal assembly in the vehicle
2) Lack of interchangabilty of the componets
3) Lack of knowledge of what does work together
4) Lack of tunes availiable, for stick shift applications
The only advantage is the cleaner look under the hood, that's if you discount the bigger throttle body assembly
But for a swap, there are good reasons to choose a newer model engine and all the new ones have DBW. Of course it can be converted with an older pcm, but if you get a full engine with computer and harness from one vehicle then that's what you get. And some of them have a really big electric throttle body, like 88mm. Also the newer engines have 58 tooth crank gears.
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If you want cruise control you needed a second cable or linkage to actuate the throttle for you... now all that can be built in the throttle body and interfaced via the tac module simply by adding a few wires, switches and a bit of programming.
From a tuning angle I can't say since I haven't burnt that bridge yet, but my next GenIII build for myself may be DBW.
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I have had a few vehicles with DBW (corvette, '05 pickup, suburban, and G8) The only one that I can complain about is the G8. I swear you push the pedal just to get rolling and nothing....so you give it a little more, and then it "catches up" and takes off quickly. Its just not "linear" like it should be or it too delayed. Kinda annoying....I may play with the tune to fix it, but I've been busy.
I also put DBW in my 68. The pedal and tac module came from the same truck. I burnt up one ECM by adjusting some parameters in the tune dealing with the gas pedal. I missed the big warning statement in HPtuner that says not to mess with it (I was just copying the tune from my '05 5.3L silverado to the 68's ECM somewhat blindly)
Alright, I'm starting to feel a little better about DBW. What are some of the negatives of DBW? How does it work in a turbo/supercharged app?
The primary reason OEMs went to the DBW throttle is traction control. If you have a mechanical connection to the motor, and someone goes WOT with the throttle pedal in a low-traction situation, things are bad. With traction control the PCM can intercept and interpret the throttle signal. If the drive wheels start slipping, it can back out of the throttle and keep you out of the ditch.
Now I'm not a GM PCM expert, but those out there who are, are all the DBW PCMs programmed for traction control? My guess is no, you have to have drive wheel spin sensors (might could use the ABS sensors) to provide input to this whole process.
Trey
T,
The primary reason OEMs went to the DBW throttle is traction control. If you have a mechanical connection to the motor, and someone goes WOT with the throttle pedal in a low-traction situation, things are bad. With traction control the PCM can intercept and interpret the throttle signal. If the drive wheels start slipping, it can back out of the throttle and keep you out of the ditch.
Now I'm not a GM PCM expert, but those out there who are, are all the DBW PCMs programmed for traction control? My guess is no, you have to have drive wheel spin sensors (might could use the ABS sensors) to provide input to this whole process.
Brings up another point, with DBW the throttle position can be reduced to save wear or prevent damage on the powertrain. 100K powertrain warranty anyone?? They make it harder for us to break the **** with an evil little thing called torque management. Torque management is the reason you can't spin the tires in many new cars. Here's a couple examples of torque management and why it sucks. I work at a gm dealer. The GMC Canyon can be ordered from the factory with a 5.3 v8 now. Sounds exciting right? ******* snooze-fest. I drove the first one we got around the block and I couldn't have been more disappointed. Floor it from a stop and you get a slight intermittent slipping sound from the rear tires, and you take off like your in mom's station wagon. In fact the only time I could feel the power when driving it was if the pedal was pressed slowly down at about 45mph. You feel the torque, and then just as it downshifts, the party's over.

I've also heard from people with late model gm trucks that they can get "stuck" with 2 wheels (left or right side) on the dirt. As soon as the throttle is applied the computer senses a wheel slip, freaks out, and shuts the throttle. I have heard of folks with these late model trucks not being able to pull another truck out that's stuck for the same reason. Apparently, even with the "traction control" off, the torque management can still shut it down.
Here are a few other reasons:
variable displacement engines (when cylinders turn off the throttle opens further)
downshift assist (anyone driven the 370Z?)
variable cam phasing (you can 'throttle' the engine with the cams and IG, leave the throttle open to reduce pumping loss)
emissions tuning
automatic launch systems (GT-R, Ferrari, porsche, etc.)
In conclusion, if you can manipulate the software and fit the pedal, go with DBW. If you don't want to spend the extra $$ and do not have huge aspirations to tune for perfect drive-ability go with the cable.
PS. it would be amazing if someone would use a mega-squirt or some other open-source ECU to make launch control for these engines.








