Whitedevil666

What is the best to use and why? What would you use and why would you choose it?

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.

Pocket

iTrader: (22)

Find a friend with a DBW truck and take it over some small bumps. If you can live with that then go DBW. If you find it annoying, go DBC

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

fucter

iTrader: (5)

DBC - cheaper(am I right?), proven
DBW - I'm scratching my head trying to SOME advantage

poconojoe

iTrader: (43)

It would totally depend on the application, if it was a one size fits all, GM would have never used both of them
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

Whitedevil666

My only experience with DBW systems has been in factory applications. For some reason ALL new cars have it, and have for several years. There must be some advantage right? I think it's the computer being able to trim it out on the highway better. Or maybe when you hit bumps with a throttle cable it moves the position slightly because of your foot, and the DBW system can eliminate that minor inconsistency and the fuel it would waste. Dunno.

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.

CalEditor

iTrader: (1)

DBW 100% for me. It is a lot better for tuning. No need for a custom built cable on conversions.

Whitedevil666

Now that is an opinion I would like to hear about. What is it about tuning that is better? Why does the factory use it?

gofastwclass

iTrader: (2)

The factory uses it because drive by wire eliminates the physical cable / linkage and allows infinite engine / drive placement options. Rear engine / mid engine car, short on under hood or under dash space - no problem! Rock crawler / sand rail / dune buggy - no problem! Suddenly engine placement and alignment doesn't matter.

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.

Black&White

Obviously both have their uses, but I've never liked the feel of DBW. My only experience with it has been in factory apps also, but I've never liked the response from DBW, always seems a little delayed. Not sure if that can be tuned out or not.

Ackattack1

iTrader: (7)

I picked DBW, for the cruise control!

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)

928vette

From an installation standpoint, I'm for DBW. The wires aren't routed to the engine and I can route/hide them very easily. From a computer standpoint, I would guess that it is better for the computer to have more accurate knowledge of the pedal position and for the computer to control the throttle opening, rather than respond/react to the throttle position.

Whitedevil666

This makes a lot of sense. The computer on a cable throttle system has to react to the already flowing air charge for acceleration enrichment. The DBW can shoot it at the same time, in theory producing better throttle response. I think there is a wide variation in factory apps for throttle response too. I drove a mazda 3 with a 5 speed for a few years, by the time I got used to slipping the clutch on that DBW system I couldn't drive my mustang or my toyota 4x4. I was jerkin' my wife's head around... She asked me if I was drinking the first few times!

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?

RobRomero

iTrader: (1)

Very informative guys. Good questions, good answers. I will be following this thread.

TomM

iTrader: (56)

DBW= Toyota.........
DBC = Home in one piece.........

Nuff said.........


T,

R-Bo

I don't think you can assume a loss of dependability with DBW. The Toyota analogy is purely anecdotal. A cable is a mechanical device that can break and leave you stranded just like bad software can. An F-16 uses "drive by wire" for all the flight-control surfaces, and the demands on one of those are a bit more than actuating a throttle to drive home.

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.

fbodygod

iTrader: (2)

drive by cable for sure way less to mess with instant throttle response less electrical which is great and you have complete control you can feel the car if you know what i mean drive my wire you press the gas it goes to the computer and the computer tells it how much to open and i would imagine DBC can open the throttle blade quicker when just punching it. but thats just my opinion
Trey

Whitedevil666

LOL!!!! Ha! That was funny. Point is anything can malfunction. I will definitely not be swapping in a toyota DBW system.

TomM

iTrader: (56)

Glad somebody got it, and you are right, anything can break, even a 30 Million dollar F-16.........IMO, less chance of failure with DBC, if the cable breaks, you are idling to a stop......

T,

Whitedevil666

Good point on traction control. An oem will call it a safety feature. And not ALL safety features are a detriment.

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.

pushrod36

There are a lot of reasons why the OEM's go with DBW. You guys have picked out a few of them (packaging, traction control, tuning, etc.). It is super easy to tune a DBW if you understand the software (the aftermarket often does not). You can tune it to make a 'peaky' engine feel like it has a flat torque curve, or you can have a variable response to make different driving situations easier for the driver to operate the throttle smoothly (ie. parking lot vs. tiping in to pass on the highway).

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.