SuperMID installation - help needed!

[landspeed]

My initial post was wrong!. It is wired in correctly (I think), I will post a scan of the ECU wiring diagram, and where I have connected the SuperMID. If I had wired the power backwards the SuperMID would probably be broken!. (but it has always powered up).

My current tests so far:

(1) It runs the same if powered from the body ground, or the engine ground
(2) All the injectors work the same way (i.e. give the odd results), ruling out a faulty injector
(3) Tested the voltage of the injectors, according to the service manual diagnostic section, and they are within normal limits.
(4) Noticed that
: when injectors are on, the fuel usage increments at a certain rate (which is the same under light load, or full turbo boost) but pulse width =0
: When throttle is off, and coasting in gear at above the idle speed, then
the the fuel usage increments much more slowly, and pulse width =0.5
(which is paradoxical).


What I'm going to do.

(1) Lunchtime : Connect the speed sensor wire to the injector wire
(2) See if I can find my spare ECU and try that (to rule out faulty ECU although I'm sure that isn't the problem).
(3) Buy an oscilloscope off ebay (expensive ), and see what the difference
is in the signal between the LPG injector emulator, and the actual injector
being connected.

(4) A question for Yoshi, if it is OK:

(a)

If this is the injector voltage trace:

On Off On Off
,,,,I^I,,,,,,,,,,,,,,I^I,,,,,,,,,,,,,,,,,,,,13V
--+ I,,,,,,,,,,,,,,+,,+-----,,,,,,,,,,,,12V
,,,,,,,I,,,,,,,,,,,,,,I
,,,,,,,I,,,,,,,,,,,,,,I,,,,,,,,,,,,,,,,,,,,,,,,6v
,,,,,,,I,,,,,,,,,,,,,,I
,,,,,,,I,+------+,I,,,,,,,,,,,,,,,,,,,,,,,,0V
,,,,,,,I_I,,,,,,,,,I_I

I have drawn transient spikes in, to show what it probably actually looks
like.

Does the SuperMID measure the changeover at e.g. 6V (which would mean it
will catch all the 12V-0V transitions), or does it measure the changeover at 12V (meaning that, if the voltage only changes between 0V and 11.9V, with tiny spikes up to 12.5V, would cause the problems seen in my case.

(b)

Is it possible to have Pulse Width 0, but have the fuel usage increasing? (i.e.
does your code use two algorithms, one for pulse width, and one for fuel usage, or, does it calculate the pulse width, *then* use this width to calculate fuel usage.

(c) I am going to have to re-wire my speed sensor (since it is disconnected on my car). It is just a simple on/off switch that goes on twice per revolution.

If I connect one side of the switch to the battery + terminal, and connect the
other side straight to the SuperMID sensor, will this be OK. e.g. If the SuperMID speed sensor wire has a resistance of 0 ohms, then the SuperMID will explode, but if the speed sensor wire has a very high resistance, it will be OK. Is it safe to do this?

(A simpler way is to say, if I touch the speed sensor wire to the battery +12V
terminal, will that damage the SuperMID due to high current flowing?

Thanks for the help!

Matt

Edit : the ,,,,,s are there for spacing purposes or the board software messes up
the formatiing.

[GasSavers_Yoshi]

Originally Posted by landspeed

Does the SuperMID measure the changeover at e.g. 6V (which would mean it
will catch all the 12V-0V transitions), or does it measure the changeover at 12V (meaning that, if the voltage only changes between 0V and 11.9V, with tiny spikes up to 12.5V, would cause the problems seen in my case.

The threshold of INJ wire voltage is about 0.7V.
The SuperMID detects logical "1" above it, 6V and 12V.
It detects logical "0" below it, 0V.

Edit: But, the current direction is improtant. The interface detects the INJ signal the current flow from the interface to the ground. The SPEED signal is opposite.

Yoshi