For anything related to the 'official' Speeduino boards (Eg v0.3, v0.4 etc)
By Lollixx
#32165
I'm not shure i'm writing this in the right section, if not feel free to mowe it where it belongs

I'm running a PNP board on my '93 mx5 for the last 10 months and 5k km

yesterday while I was cruising on the highway my car just died, tach dropped to 0 and it stayed there forever
at first I tought about the CAS signal missing but then I realised it was no fuel pump priming when I turned the keys on, so something worst has happened

I opened the case and nothing was lighting on speeduino or arduino when I powered the ECU
also nothing seems visually broken, like weldings or anything burned
connecting it to tunerstudio and arduino worked fine but there wasn't any difference between power on or off except the battery voltage gauge that was right on, averything else was freezed on the same reading and completly unresponsive

putting back the stock ecu the car starts and works fine so I would say that everything's right there

for what I can see I think the voltage regulator is dead
please tell me it's something fixable (doubt it, it's all SMD)

P.S. english is not my first language, hope everithing I wrote make sense :P
By moonie223
#32170
The voltage regulator is onboard IC7 MC33814 on the MX5 PNP board. It has an enable pin, KEYSW, on pin 37. If you have 12V on that pin and no 5V output on VPROT pin 20 and VCC pin 17, then the regulator is probably dead. KEYSW is actually a ignition switched source, 1B on the connector.

I think you might be able to build a linear regulator in the proto area, might need to use an extra digital output to control the fuel pump as well, bypass the dead IC7. The MC33814 also has a watchdog, but as far as I can tell it's not used. SJ1 should be disconnected, no solder bridge.

Also, you might want to check the jumper bridge you should have installed at the AFM connector. If for some reason that comes disconnected, then the circuit opening relay will not open and you will never have 12V on 1B, never get 12V at KEYSW, and never get any 5V! But, you still have 12V at 1A at all times, it's VBAT, and BRV is sourced from VBAT!


Hope this helps!
By Lollixx
#32176
turboedge wrote:Check the "room" fuse in the fuse panel. The OEM ECU can operate without it, the Speeduino depends on it.
that's the first thing i checked when I notiched it wasn't priming the fuel pump but all fuses are good
the board also does the same on the bench when feeded directly with 12v
By Lollixx
#32196
noisymime wrote:When being fed with 12v (In the car if possible) what does TS indicate the battery voltage is?
when I feed it some voltage tunerstudio reads it right, and that's the only thing that changes when I turn the key on when connected to TS
By lsdlsd88
#32714
moonie223 wrote: Sun Feb 17, 2019 4:01 pm Also, you might want to check the jumper bridge you should have installed at the AFM connector. If for some reason that comes disconnected, then the circuit opening relay will not open and you will never have 12V on 1B, never get 12V at KEYSW, and never get any 5V! But, you still have 12V at 1A at all times, it's VBAT, and BRV is sourced from VBAT!
what jumper bridge are you talking about exactly? never have any issue without.
By moonie223
#32728
It's all documented here...

https://speeduino.com/wiki/index.php/MX5_PNP

Stock 1.6 miata have a dual coil circuit opening relay for the fuel pump, the ECU holds it open long enough for the engine to start, then the wind vane in the AFM holds it open. This is hard to tune around, megasquirt 1.6 miata just wire the fuel pump output to the AFM wiring, then put a jumper to simulate the flapper being on. If the engine stalls megasquirt kills the fuel pump output.

For some reason speeduino pro board doesn't do it this way. It uses battery (always hot) on 1A to switch 2O on when the ignition switch (1B) is hot. This is done through the MC33814. Seems a huge waste of what is an entire ECU controller, all I can see it do is switch the fuel pump (and circuit opening relay, injector power, idle valve power etc...) on while regulating 5V.

If the MC33814 dies, nothing else will work. It's the linear regulator that powers the arduino. If you hook the arduino up to USB power and you see 12V, that's because it reads off Vbat, always, always hot.

Hopefully this helps!
By lsdlsd88
#32730
moonie223 wrote: Mon Mar 11, 2019 8:47 pm It's all documented here...

https://speeduino.com/wiki/index.php/MX5_PNP
this is all clear and good, my confusion came from the sentence "the jumper that you SHOULD have installed", while in the wiki it's explained as an ALTERNATIVE fuel pump control.
I can't see why someone would want to use the alternative method, so I imagine 99% of users do not and SHOULD not have installed any jumper wire in the AFM connector.
By moonie223
#32734
You're powering the momentary back half of the dual coil relay full time when it's designed to run off the AFM switched half of the relay. My schematic shows extra circuitry on the secondary coil, resistors and capacitors, the one would be powered full time off the main relay.

Maybe it keeps working, but it's not right. It's not how factory did it, and it's not how decades of megasquirting has done it.

But I stand behind it, should be using O2 and "alternate" fuel pump wiring. Still have to pull the start signal fuse, it's useless once you've got real ECU fuel pump control anyway.

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