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Testing Typical Hardware While Building It 
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My simple guide to testing your inputs:

For example, a Jaguar A3 has the following inputs:

  • CHT
  • IAT
  • MAT
  • TPS
  • O2
  • BRV
  • MAF
  • MAP
  • Crank
  • Cam

Which fall into three broad categories:

  • Linear analogue (TPS, 02, BRV, MAF, MAP)
  • Thermistor biased analogue (IAT, CHT, MAT)
  • Timed pulse RPM/Position (Crank, Cam)

Obviously if MAP is soldered into place, and not wired externally, then just hook up a hose to it,
and get your partner to suck on it. Expect 5-10kPa depending on her talent level. If you do it
yourself, expect maybe 50kPa. With the correct sensor configuration an open MAP sensor should
read between 95 and 105kPa at sea level and as low as 60kPA at the top of a mountain. If MAP
is externalised, the input can be tested the same way as the other linear sensor inputs.

For the linear circuits, hook up the ends of a potentiometer to 5V and Ground and the centre tap to your sensor input:

Image

You should be able to see the appropriate value move up and down in a suitable tuning application or log viewing application.

Note, BRV will only read between 0 and 5V with this technique. After doing
this, you can, at your option test BRV the same way, but make sure to NOT
apply more than 5V to the other inputs, or you may damage them.

For the thermistors, the input is biased to 5V so you simply need to ground the input with various strengths to test that it works:

Image

The same applies here: You should be able to see the appropriate value move up and down in a suitable tuning application or log viewing application.

Note, a 10k pot is just as suitable, and in fact, I prefer 10k, 1k is Preston's value.

For the RPM/Position inputs, you can use the 0-5V pot setup too:

Image

Just load the listener firmware and check that the count increments
appropriately as you wind the knob up and down. Values to watch are:

  • primaryTeethSeen
  • secondaryTeethSeen

Alternatively, you can use a square wave from a 555 timer or FredStim (or JimStim if you're desperate) and a proper decoder to measure RPM.

I hope this helps!

Fred.

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Sat Dec 01, 2012 10:19 pm
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n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Sat Dec 01, 2012 10:24 pm
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Reserved for communications testing! IE, will move first post down one.

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n00bs, do NOT PM or email tech questions! Use the forum!
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Sat Dec 01, 2012 10:25 pm
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Reserved for power supply testing.

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FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Sat Dec 01, 2012 10:25 pm
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