03 HD Gas pedal!

Jester4736w · April 17, 2005

Has anyone noticed how touchy the gas pedal is on our trucks? I was told it was because they were electronic, is this true? Every bump i hit it takes off on me, lol... Any feedback?

snoman · April 17, 2005

Has anyone noticed how touchy the gas pedal is on our trucks? I was told it was because they were electronic, is this true? Every bump i hit it takes off on me, lol... Any feedback?

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That truck is drive by wire with no hard link between foot and "throttle plates" so it can be touchy some times.

michigan2500hd · April 17, 2005

03 and up have the throttle-by-wire system. Of all the fuel injected trucks ive had this system is by far the dumbest idea gm has had. ( at least as throttle drive is concerned) There is a huge dead spot as you push the gas from a stop and then when you hit a bump you lose or gain speed as your foot jumps around. Anybody know if this can be adjusted somehow? I would love to go back to the cable system but im sure the computer (pcm) would become a retard.

GMC6000 · April 17, 2005

FYI, 1994 on up diesels had the throttle by wire. I, for one, prefer this over the old throttle cable. The drive by wire has much quicker throttle response than the cable.

Bgdsub72 · April 17, 2005

that was one of the first things I noticed when I bought the 04. It gets annoying but I have learned to back off the gas when I am anticipating a dip or bump.

mmmikkke · April 17, 2005

I noticed this while replacing my sound system on my brand new 05. Actually, I knew something was up before that when I realized that the cruise control doesn't move the pedal any more. I used to set my foot lightly on the pedal before I turned off the cruise, so that I could take over control without decelerating. I miss that.

But while running the power wire for my amp, I saw the new setup, it's all self contained about 6" above the actual pedal. Your moving of the pedal is sensed by this thing that's about the size of a roll of quarters. There's no throttle cable any more at all.

Since then I've tried to see what's *good* about the new setup. And I decided that I like it. There's no stiction any more. The pedal moves directly in proportion to how hard you press it. You don't have to think about pedal position any more, you just have to think about pedal *pressure*.

It can make for some really nice smooth takeoffs.

Try moving your seat back. And then think pressure, not position.

snoman · April 17, 2005

FYI, 1994 on up diesels had the throttle by wire. I, for one, prefer this over the old throttle cable. The drive by wire has much quicker throttle response than the cable.

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I would have to disagree with that. None of my vehicals are drive by wire (my newest is a 2 ea 2000 models) and I have driven many drive by wires and I do not care for their feel or responce and I do not find them at all more responce than a good drive by cable system that I am in total control of engine output at all time with no ECM second guessing what I want or need. I bellieve GM went drive by wire in 2000 with NBS trucks across the board as my 2000 is a OBS and still drive by cable. ALso in 94 the 6.5 got a electronically control injection pump but did not get true drive by wire until 98 or 99.

Jester4736w · April 17, 2005

Somebody explained that "drive-by-wire" deal to me once but i wasnt sure whether to believe it or not. Now i know... But i must say i don't really care for it much at all. I haven't really noticed the quick lag people are talking about, but it drives me absolutely CRAZY the way my foot is constantly bobbing up and down and taking the throttle with it, lol. Don't get me wrong it's not a problem (Not complaining) just wanted to rant with you guys a little and see what you all thought. Thanks for the info all, im glad im not the only one that felt this way. I thought i had a retarded foot or something.

Butch 02 Denali · April 17, 2005

Drive-by-wire was used first in the 2001 GMC C3, then in all the 2002 Denali's, Sierra Denali's, Escalades and some HD's. In 2003 it became standard in all the GM trucks.

GM added the delay to help the "bump throttle" problem that many were complaining about. In 2001, the delay was very slight, they added more in 2002, even more in 2003, ans still more in 2004. I don't know what they did in 2005. The delay is programmed in the PCM and can be removed by any competent programmer. Removing the delay, does make the bump throttle feel a little worse. The best fix is to add a stronger spring on the pedal. Many have used the spring from a SUV pedal, for some reason, they have stronger springs than the pick-ups.

Personally, the bump throttle has never bothered me and I had all the delay programmed out by Wester's years ago. Maybe I just got used to it! I drive my Sierra Denali with Drive-by-wire and another truck with cable throttle almost daily, and I do like the smoothness and instant response of the electronic throttle much better.

snoman · April 17, 2005

Drive-by-wire was used first in the 2001 GMC C3, then in all the 2002 Denali's, Sierra Denali's, Escalades and some HD's. In 2003 it became standard in all the GM trucks.
GM added the delay to help the "bump throttle" problem that many were complaining about. In 2001, the delay was very slight, they added more in 2002, even more in 2003, ans still more in 2004. I don't know what they did in 2005. The delay is programmed in the PCM and can be removed by any competent programmer. Removing the delay, does make the bump throttle feel a little worse. The best fix is to add a stronger spring on the pedal. Many have used the spring from a SUV pedal, for some reason, they have stronger springs than the pick-ups.

Personally, the bump throttle has never bothered me and I had all the delay programmed out by Wester's years ago. Maybe I just got used to it! I drive my Sierra Denali with Drive-by-wire and another truck with cable throttle almost daily, and I do like the smoothness and instant response of the electronic throttle much better.

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You are just used to it thats all because it will never be as precise and instant as a direct connection vs a reostat and servo that has to have the ECM translate whether it be throttle on or off. When I give a quarter throttle with a cable I KNOW I am giving a quarter throttle for sure but with drive by wire you never really know what the ECM is telling the servo to do. Yes you can "tune" it but you still never really know and that custom tune may actually give it half throttle of more at first to make it feel perkier and may also vary the throttle plates as well even with no change in input for you. With a diesel today there is no moving throttle plate today so it makes less diference there but not so with a gasser.

oldguy · April 17, 2005

I've got a set of road "swells" up the road from the house that set my truck up so that I have the throttle situation that we are talking about .

I just pretend that I' in one of these........................

Butch 02 Denali · April 17, 2005

Snowman, i have datalogged over a dozen drive-by-wire 6.0 trucks with my Auto Enginuity Scanner. It samples 40 times a second and has readouts for requested throttle angle (the pedal) and actual throttle angle (the throttle blade). In no circumstance has there ever been any hesitation or discrepancy between the two. Full throttle runs through the quarter, punching it from a standstill, downshifting at any speed or punching it at any speed, the pedal always matches the throttle blade exactly. Only the 8.1's have the throttle opening delayed by the GM abuse tuning. This can also be eliminated by Wester's now.

As I said, I drive them both daily, and the drive-by-wire is more responsive than the cable throttle, that is why they bounce going over bumps, though not as bad as oldguys!!! LOL

Jester4736w · April 18, 2005

The way the pedal is constantly being pushed in and out, will not cause any damage correct? I'm a compulsive worrier with everything... But, i did hear that when at a constant rpm the pcm will make everything run smoother and cleaner for the engine, with that "bounce" problem it seems like the pcm could never do it's job correctly? Just a thought, probably has no backbone.

whitesnake01 · April 18, 2005

Just think of the pedal as controlling the "whishing" rpm/speed and the computer then controls the actual rpm/speed. The goal is to keep them close and the lag small, without causing too much pollution. In the past, the lag was smaller at the expense of more unburnt or partially burned fuel.

mmmikkke · April 18, 2005

I'm going to try to figure out tomorrow why some of you guys have a problem holding the pedal steady. I really don't think I have this problem, because I can just imagine if I did, it'd drive me nuts.

Maybe my seat is back just the right distance...Maybe my foot's bigger...Maybe I cam off the trans hump when I drive...I'm going to try to come up with some ideas for you guys if possible.