Accelerator Pedal Travel

OneWayRacer · January 20th, 2010, 09:00

Does anyone know how important pedal travel is? I pulled the accelerator out of my parts car to begin fitting it into my project car. I noticed that the pedal assembly has more travel capability than what the factory mounting and stops allowed it to use. Do I need to build proper limits to that I don't exceed what factory limits were or is there any harm in allowing it to travel the full possible distance? If no harm is done is there any gain in allowing full travel? Pedal is out of a 2003 Jetta.

Lug_Nut · January 20th, 2010, 15:33

The ECU is 'adapted' or "learns" the minimum and maximum resistance values of the pedal. If zero to 100 is in 20 degrees of potentiometer motion, or 22, it doesn't matter as far as the engine is concerned.

OneWayRacer · January 20th, 2010, 20:01

I do understand what you're saying, but maybe need to explain a little better what I'm asking. Mounted to the floor purch the potentiometer pedal reached it's travel limit when it hit the bump stop on the bottom side of the pedal. Once out of the car where there is no bump stop the pedal is able to move about 1/2" farther. Using example numbers as you did lets say that in the factory location the pedal had 20 degrees of motion. The computer is programmed so that is sees that 20 degrees as the full throttle 0-100. However once the pedal is removed it can now travel 25 degrees. You can't just cut your pedal down to 10 degrees of motion and expect the computer to still give you full throttle without reprogramming it. So likewise would the computer need to be reprogrammed with 25 degrees or would it reach full throttle at 20 and the other 5 is useless travel. Or would it somehow throw a computer fault since you're going beyond what it thinks is full throttle. Hope that makes sense.

G60ING · January 21st, 2010, 07:48

The mk4 go pedal has its stop point built into the pedal cluster. I remember this very specifically because when i swapped the mk4 go pedal into my 1st tdi corrado I reeforced this point because it seemed like a place that could become stressed.

I don't recall my 99.5 donor car having a stop point on the floor.

CFM · January 21st, 2010, 16:28

I noticed that the AHU pedal I have in my Saturn TDI conversion has some adjustment - a nice feature. I haven't done so yet, but I need to bend the pedal arm a bit so that it hits the floor at full throttle, then re-fine-tune the adjustment.

OneWayRacer · January 21st, 2010, 20:48

Alright here are a couple pictures to show exactly what I'm talking about. First pic is bolted to mounting plate in the car and second is obviously out of car. You can see by the lower circle that the stop on the pedal arm limits the travel and you still have a gap before contacting the potentiometer housing (top circle). Out of the car you can push the pedal past this to where it stops against the housing (circle 2nd pic). Is this addition travel going to cause a problem electrically to where it might cause a computer fault code since you're going beyond the range that it was using. Or is it just going to be excess movement with no effect good or bad. Maybe not as big of deal as I think, but if I have to limit travel to how it was in the car then I want to build my new mount correct the first time.

G60ING · January 22nd, 2010, 03:31

the bottom stop of the first picture allows enough movement for the pedal to hit 100% throttle.

Lug_Nut · January 22nd, 2010, 05:24

You will gain nothing but a weight savings of a few grams by removing the stop.
Both conditions can provide full 0% to 100% output.
The ohms resistance may change from, say a range of zero ohms to 200 ohms, to a new range of zero to 220 ohms, but the ECU can be 'taught' to use the new 220 ohm value as the new 100%.
Go the other way with a longer stop and the 180 ohm can be taught to be interpreted as the new 100%
Net result: no change.