Throttle adjustment
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From: Atlanta, GA
Throttle adjustment
I have a 2000 excursion with a PSD. There seems to be an excessive amount of free play in the accelerator pedal. When the engine is idling, you have to depress the gas pedal some distance before the engine responds. Also, I hear a small clicking sound like a micro switch activating during the free play travel. Is there a micro switch and if so what does this control?
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The diesels have a "drive by wire" throttle. The microswitch is positive confirmation to let the engine know that it should be at idle, while the pedal just moves a potentiometer when you press it.
Basically, that's how it works, you should just get used to it. There's no mechanical connection to a throttle plate or anything, so there's some motion at the bottom that doesn't produce a linear response in engine RPMs. Having said that, it could be that yours is out of whack, if you need to press the pedal an unreasonable distance before the switch actuates. People have taken their pedals apart before to put more of a hair-trigger adjustment on that switch; you really don't want to overdo it and have the switch not be tripped by the pedal returning to its rest position though! It really needs that, to calibrate the rest of its motion properly.
Duncan
Basically, that's how it works, you should just get used to it. There's no mechanical connection to a throttle plate or anything, so there's some motion at the bottom that doesn't produce a linear response in engine RPMs. Having said that, it could be that yours is out of whack, if you need to press the pedal an unreasonable distance before the switch actuates. People have taken their pedals apart before to put more of a hair-trigger adjustment on that switch; you really don't want to overdo it and have the switch not be tripped by the pedal returning to its rest position though! It really needs that, to calibrate the rest of its motion properly.
Duncan
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Officially it's not adjustable. You can bend things to make the switch actuate at a different time.
The newer pedals got rid of the switch, and suffered for it - they use 2 or 3 potentiometers and do the idle determination "in software" but physical and software problems were causing issues at first. Some of the "dead pedal" reports really were a dead pedal assembly! I think that happened more on the adjustable-pedal models for some reason; there was an actual recall on those.
Duncan
The newer pedals got rid of the switch, and suffered for it - they use 2 or 3 potentiometers and do the idle determination "in software" but physical and software problems were causing issues at first. Some of the "dead pedal" reports really were a dead pedal assembly! I think that happened more on the adjustable-pedal models for some reason; there was an actual recall on those.
Duncan
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