Unusual Gas Pedal

[ctrcbob]

I've been wondering about this for a while on my V8. (V6 may be different).

DO THE FOLLOWING WITH THE ENGINE OFF!!!!
DO THE FOLLOWING WITH THE ENGINE OFF!!!!
DO THE FOLLOWING WITH THE ENGINE OFF!!!!

If you push the gas petal SLOWLY down to the floor, you will notice that when the petal gets ALMOST to the floor, for the last inch or less, it has more resistance, as if it is pushing a hidden switch. (Note that the Genesis is a drive by wire system). I'm wondering if this is somehow something to force the transmission down into a lower gear. I know that the car will drop down a few gears even when not going down all the way to the floor. Other cars I've had did not have this "feature".

In the past, I never really noticed it when driving and passing cars, perhaps because I was "excited" when passing and did not pay attention, or perhaps because I did not need to "floor it" in order to pass cars quickly.

(Now you can have the engine on)

OK, now that you know what to expect, the next time you pass a car, or floor it for any reason, you will feel it and know about it.

I have no idea why it was designed into the Drive By Wire system, but it has to be there for a reason.

 

[Dimitry]

Re: Unusual Gas Petal

From my experience, it's to unleash all the power of the engine, at the fastest the computer deems fit. I like playing in shiftronic mode, and I can tell you that if you depress the pedal to that point, it overrides the shiftronic and gets you moving in the lowest possible gear.

 

[mikec]

Re: Unusual Gas Petal

Sounds like a normal "kickdown" switch. Most auto tranny cars have something similar. When you really mash the gas to pass, this switch trips, forcing the tranny to downshift more than its usual MPG-sensitive programming deems necessary.

On many cars, you don't "feel" it so much; you might hear a faint click though. I know when I first started driving my Genesis that pedal stiffening felt like the stop to me... the first time I really pushed through it was a real eye-opener. I'd been babying it up till then, doing the break-in thing.

Many older carburetor setups had something similar: a "stiff spot" in the pedal travel to let you know "you're about to open the secondaries and kill MPG while roasting the rear tires." The feel of the Genesis pedal reminds me of that - "you sure ya wanna do this? Are you really ready for the fun stuff?" stiff spot.

mike c.

 

[Mark_888]

Re: Unusual Gas Petal

If you push the gas petal SLOWLY down to the floor, you will notice that when the petal gets ALMOST to the floor, for the last inch or less, it has more resistance, as if it is pushing a hidden switch. (Note that the Genesis is a drive by wire system).

I don't know the answer, but I would not be surprised if there was spring on the gas pedal to make sure it pops back when you take your foot off the pedal. I don't see why that is in any way inconsistent with a drive-by-wire setup. I would guess that the spring tension varies depending on how much it is compressed (as would be the case with almost any spring).

 

[mcginnpm]

Re: Unusual Gas Petal

Mine has a pretty loud click, and it only travels about a half inch after the click.

The schematic on www.hmaservice.com for the Accelerator Pedal Position Sensor (attached) shows 2 solinoid circuits going to the ECM from the Accelerator Pedal. One circuit interfaces with the A/C system (the one associated with the click?), which probably tells the A/C to shut down when max power is being called for with a floored accelarator pedal.

I checked the schematic for the automatic transmission control module and there is no interface with the accelerator pedal.

 

[Yama1yzf]

Re: Unusual Gas Petal

Noticed this in my car as well and brought it back to the dealer for it. They said it was there for a "kickdown" of the transmission but if that is the case it seems like a bad way to do it. I pushed down on it by hand with the car off and you can definitely feel it so I was worried it would hang up when I floored it. My other cars accomplish this electronically and do not require a detent in the pedal. And if there are no wires going to the pedal per the schematic then why is it there?

 

[mcginnpm]

I'm guessing since there is no direct wiring interface from the accelerator pedal position sensor to the TCM (transmission control module) that there must be some sort of "master logic" in the ECM (engine control module) that communicates with the TCM to tell it to "kickdown" when you floor it.

I'm not really sure why they put the "mechanical click" in the pedal? I'd never even noticed it until ctrbob brought it up, so it's not an obvious feedback to the driver.

 

[ctrcbob]

Like I said before, I never really noticed it until recently. There have been a few times I had to pass a car quickly, and (I think) I pushed the petal down what I thought was the floorboard, and the car shot up over 100mph but I probably only pushed it down to the detent. (I don't drive them hard <grin>) Next time I have to pass quickly, I will pay more attention, and will FLOOR it and see what happens. (probably on those very rural roads in West Texas or New Mexico as I don't normally go up to 100mph).