Mazda ECU on a bench

[AndreyB]

I've got some people interested in Miata PnP ECUs so I need to put the Honda VR stimulation on hold and switch to Mazda ECU stimulation. This one is much easier since trigger signal is just the trivial open drain, I have discovery pin configured as open drain and it is connected directly to Mazda OEM ECU, and it seems to be working!

Trigger signal

And here you are - there is life in ignition control wires!


Only problem is I do not read anything in the injector wires. I have a potentiometer on the air meter line, it's a VAF for http://rusefi.com/wiki/index.php?title=Vehicle:Mazda_Miata_1990 and MAF for http://www.rusefi.com/wiki/index.php?title=Vehicle:Mazda_Miata_1994 - I happen to have both ECUs in my collection.



I do not want to believe that I am not getting fuel signals because of the lack of CLT or IAT sensors, but I do not know why I am not getting signals in the fuel lines. I am trying to read it as low side driver - continuity mode on the multimeter and trying to drive an LED with it. Nothing

[AndreyB]

Same deal with a 1990 ECU I have. It's impossible that both ECUs are bad, I must be missing something.

Still no fuel even with 1.5K pull-down on IAT and CLT wires.

[kb1gtt]

What is the voltage at the IAT/CLT with pull down? I suspect you are correct in making it a pull down, but you may need a pull up. You should have some voltage on the pin.

[AndreyB]

The voltage is ~1.7v which corresponds to 2.7K pull-up to 5v inside the ECU.

I would bet someone's else kidney that the engine would run without CLT and IAT sensors.

[AndreyB]

Nothing on injector wires with CLT and IAT sensors. Looks for fresh ideas it must be something silly...

[Nobody]

Likely bouncing off of a sanity check...

[AndreyB]

Likely bouncing off of a sanity check...

For sure... Which one?

[AndreyB]

Maybe http://forum.miata.net/vb/showpost.php?p=7102782&postcount=4 ?

[AndreyB]

Status update: I've got the fuel signal once I've provided 'tach signal' which grrrr the same inverted spark out signal produces by the ECU itself. Apparently they have something funny inside the ECU, probably for historical reasons?

This POS is pretty smart - I had to put a transistor for each spark wire so that I have proper RPM at the tach line - with half the RPM it would not supply fuel.

[AndreyB]

Now working on the stimulation control usability. Here's timing advance from 1990 Miata.

[AndreyB]

[video][/video]