Electro-Metro Pot Box Installation

by admin on December 21, 2008

I headed over to Tom’s today to work on our cars.

Rich was already over there, and Swee and Lloyd both stopped in for a bit. Right after lunch, Mike showed up and helped out for a while.

Mostly, we worked on our electric throttle controls.

On Tom’s Neon, the original car throttle body already has a 0-5K pot box built in. Although his controller isn’t expecting a 0-5K pot, the way a Curtis or Alltrax controller does, it sure is handy that his gas car already has an electronic signal built in it.

On his car, the gas pedal goes to the throttle body, which will send the signal to his AC controller.

Rich worked on rigging a microswitch to the throttle. The idea is that this microswitch will turn the AC controller on and off. This should allow the car to be set to regenerative breaking any time your foot is on the gas, but the car is moving faster than the throttle would make it go. Think engine braking that recharges the batteries.

With the foot totally off the gas pedal, the AC controller will turn off and allow the car to do a true coast. Nice to have the option to either regen OR coast based solely (ack! a foot pun!) on what you do with the pedal!

Last week on my car, I threw in the new Curtis PB-6 potentiometer. Since then, I hadn’t been able to hit a great top speed. I checked it with an ohm-meter, and sure enough, I wasn’t getting all the way up to 5000 oms. It was topping off around 3500.

Since the original throttle cable threaded straight into a part no longer in my car (the ENGINE!) I needed a new way to pin down the end of the cable. It seemed like the easiest way to do this is to drill a whole in some sort of small box, and run the cable into that.

Tom dug up a decent-sized project box, complete with gasketed seal. I measured how tall the potentiometer was, and marked that height on the side of the box. I drilled a hole right there to run the throttle cable through.

I ran the cable through it and attached the cable to the arm of the Curtis PB-6 potentiometer using a “throttle accessory” nut from the hardware store. That added another $3.40 to my project cost, but it sure was handy to be able to directly attach the cable.

I ran the ends of the pot box cable to an ohm meter to be able to measure the resistance at different positions. Mike ran the gas pedal, while Rich moved the potentiometer inside the project box until the ohm meter read 0 with foot off the gas, and 5K with it floored. Then I marked the mounting holes of the PB-6 on the box in that position.

After drilling the holes, I mounted the pot to the project box with M5 metric bolts and re-attached the throttle cable. Now we could use the nuts on the threaded end of the throttle cable to fine tune the distance between the box and the arm of the PB-6, and again measured it with the ohm meter.

Once it was all set, we used self-tapping screws to mount the Pot Box directly to the firewall and finally pinned up the vacuum canister in a semi-permanent manner.

Tom also found the right plug and grommet to cover the hole in the bottom of the box and to go around the cable that comes out of the box to the controller. No snow or slush is getting in there!!

When all was set and running again, Tom and I went for a spin around the block. The response and speed of the car is much improved. The car actually handles pretty well on the snow-packed roads. I don’t have very good tires on the car, only what came with when I bought it, but it seems to handle pretty well. The car sits low and solid, with plenty of weight on the drive wheels.

Tom also commented that it sounded much better than it did before.

The Metro is back on the road.

Now I just have to deal with that speeding ticket and emissions testing!!!!

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