TedMosby

Hey guys,
Not sure if this is the place to ask this, but here goes;
I've got a '03 DBW 5.3 sitting on the stand that I bought without a pedal and TAC module. Just bought a pedal and TAC off ebay. I have connected JUST-
the PCM 12v constant (orange) and 12v switched (pink)
12v to the tac connector (pink)
grounds to the block
Pretty sure that's all I should need at this point, to see if the new pedal and TAC are working.
Now, it works...sorta....but my question is this...at zero pedal, my TB is just above zero opening (looks good for idle I guess).


At half...ish pedal the TB is already at WOT


And remains at WOT for the rest of the pedal's travel.


It doesn't sound like it's over-driving the TB stepper or anything, but I've worked with steppers and servos before and this just doesn't seem right to me. I would guess that I'm using half the resolution of the controller to go full motion on the stepper (that just wouldn't cut it on a cnc machine). Has this been the same for anyone else? Is there normally a bump stop under the throttle pedal that keeps it from bottoming out on the bracket anyway, or should it go full motion to the bracket? Should I be concerned with this at all? I haven't taken the sensor off the pedal, or messed with anything yet, I figured I'd ask here if it was normal first.

Thanks.

garys 68

iTrader: (1)

Some vehicles came with an adjustable gas pedal. They seem to have this issue. Do a search here.

spot_55

i have an 05 dbw in my chevelle and around half throttle pedal movement it is at 100 percent throttle and stays that way through the rest of the pedal movement. however with that said it seems to want to bog a bit once you go past the half pedal movement but have not had any real issues with it. somewhere i read on here said that theirs goes into limp mode when the pedal is pressed too far( mine has not done this) so they made a stop for the pedal at 100 percent so it wont go any futher. hopethis helps.

TedMosby

This one's non-adjustable. I guess that doesn't mean the PCM isn't programmed for an adjustable pedal. Unfortunately the guy I bought the engine, harness and PCM from said it all came from the same truck but he didn't really seem to know. He said he was selling the stuff for his cousin who bought it at a swap meet or something. The PCM is missing the VIN sticker.

I did do a search (here and on google), and basically found one member (Jim_PA) having the same issue. He's posted about it on several sites and found no definitive answer to the problem. He wound up changing parameters with HP Tuners (which I don't have...yet).

Thanks.

TedMosby

Yeah it does help, thanks. I actually went out and measured the travel at the pedal pivot on my 03 Dodge Ram. It was about 1.75". I then measured how much travel it took to get the TB on the 5.3 wide open, and it was about 1.75" at the pedal pivot. It would be nice to have a Silverado to look at, maybe I'll take a trip to Pick-Your-Part tomorrow. Sucks that they're all the way over in Burbank, and never seem to have anything newer than 1996.

The thing that concerned me was
#1 This is going in a 2200lb car that my 17 year old will be daily driving, and I didn't want a hyper sensitive pedal (Some day I'll tell ya the story about accidentally pulling the front wheels off the ground in front of a cop in my buddy's VW with a ridiculously sensitive pedal and sticky carb linkage.).
#2 I'm gonna have to shorten the pedal, effectively decreasing the amount of travel, making it seem even more sensitive.

If I get a chance to measure pedal travel on a silverado, I'll post the findings here.

Thanks again.....I shoulda kept my Chevelle....

aknovaman

iTrader: (7)

Dbw pedals are very insensitive (slow responding). The Dbw pcm tables are set up for a bouncy 4x4 truck so it will not snap your neck.

TedMosby

Yeah, I read that somewhere. In fact, the guy from lt1swap.com says he can program the PCM for better/quicker response of the DBW setup. Maybe I'll hold off on that option till we get the thing running and see how it acts.