[Driving] Porsche eBoxster 986

[modellfan]

Documentation will follow

[Tomas]

We want more information about this one please!

[modellfan]

Bug 1: Pedal Potentiometer

currently, I am in a phase of bug fixing, before I will go into re engineering the battery to a double capacity. One of the bugs is, that I don't get a stable pot 2. Basically the offset of pot 2 is jumping. Not completely random, but from one plateau to another occasionally. This leads to throttle 2 error messages in my Tesla SDU software. With throttle two disconnected, the car drives perfect. Possible error causes for could be:

• potentiometer defect

• wrong wiring

• bad connector

• emv problem?

• problem in SDU board electronics

Because Porsche 986 ptentiometers are known to fail, I bought another used one and changed it. Same problem as before. Now I connected the old one to an arduino running the digits to percent code from SDU. Looks more or less perfect to me:

[jrbe]

Edited

Looks like maybe some capacitance difference between channels for some reason.

[uhi22]

If the pot2 offset is changing, this sounds like a bad connection of the pot2 minus wire. If it is possible I propose to connect a multimeter at pot2+ and pot2-, to check whether the voltage is stable.

[jrbe]

A few steady throttle position step logs might also help see what's going on. Like 5, 10, 15, 25, 35, 50% etc. But hold each for 1/4 second or so.

And to uhi's point, are connections good? Bad crimps can be easy to miss.

[modellfan]

Cluster Instrument Modification

As I know from other conversations that most of the cluster maybe except the fuel level can be controlled via CAN bus , I started this work package with the hardware modification. It was important for me, as for the full vehicle to stay within Porsche design language of this time. How would Porsche have designed and built an electric car at this time.

First I scanned the original cluster disc for the RPM. Then I had a friend design me in Photoshop a modified one. I cut a 0.3 mm frosted acrylic glas on a laser cutter to the exact dimensions. Then on a vinyl cutter I cut out two layers of vinyl. Upper layer on one side of the acrylic glas is Blockout Vinyl for light advertisement in black. This was basically two steps - the normal cut out and then the missing little pieces for the middle of the „0“ and „D“. On the other side of the acrylic glas translucent vinyl in green, blue and white. The translucent black one wasn’t really translucent at all. So I took overhead projector plastic and printed different test patterns in different tones of gray to fill the symbols for signal lights and high rpm. At the end I put several layers of matt clear paint on the front to fix especially the very small parts for hotter temperatures.

[Bratitude]

Impressive. So are you going to re index the needle or no need just set position via can and it will hold there

[modellfan]

According what I see from other conversations just send the oneor two bytes responsible for rpm. I will write a small code for Zombie to calculate it based on the data from battery (max power possible ) and SDU ( drive selection, current power ).

[Mitchy]

That is amazing!
Great work.

If you're looking to control the fuel gauge, if it's anything like the newer stuff, I've been using a 1Kohm AD8403, with two of the resistors in parallel, to make a 500ohm variable resistor.

The newer clusters seem to monitor the line resistance, sorta' akin to a 3 or 4 wire RTD. So it always expects to see a pretty constant resistance across the element.

[modellfan]

Not there yet. From my understanding the cluster is doing some Karman Filter based on current consumption received via can from the Engine ECU and analog signal from the reservoir Level.
I still hope , that by coding and sending the right can messages , maybe also UDS can messages I can move the fuel gauge to the right position .