talisker

i installed my diypnp about a week ago, had a few problems with some of the wires that were not in the right place which you guys helped me with and the guys been running great apart from the other day it would not start and i thought i couldn't here the fuel pump running, so jumped it at the diagnostic socket and fired right up.
so now it won't run unless i leave the wire in the diagnostic socket, i read that you can bridge a couple of wires in the AFR but it seems strange that it worked fine for a few days.

Braineack

iTrader: (62)

who built the DIYPNP?

talisker

it was built by extraefi in the uk, but the guy i bought it off had the pinouts altered supposedly to suit a later car, a uk 1997 1.6 fuel pump did work fine for a couple of days.
to be honest it's a bit of a mess, the tach wire and the fan wire were in the wrong positions and today i fitted a VTPS couldn't get it to work and found the wires were also in the wrong positions, all sorted now so hopefully everything else is ok.

jstck

On my 1997 1.8 Euro-MX5, the fuel pump relay was not on the usual pin, 1U, but on pin 1V right next to it. The cable is still light-green though. The cable I have on 1U in the car wiring harness is light-green with a red stripe, and I have no idea what it does (car runs fine with it not connected). I haven't found any documentation matching that particular bit of wiring in my car, but maybe your diypnp has been modified to match a car with similar wiring, or some such.

talisker

my car is a uk spec 1997 so is probably similar to yours i've found it almost impossible to find a wiring diagram for this car, i will have another look at the wiring at the weekend.

jstck

So far, I've only discovered a few differences between my cars ECU wiring and whatever commonly found wiring diagrams I've found online for 97 Miatas:

• The already mentioned fuel pump relay wire. Moved from 1U to 1V next door, leaving a mystery wire in its trail
• An immobiliser under the dash on the drivers side, that has some kind of data connection going to the ECU on pin 1S (blue wire). I needed that connected when I ran the stock ECU via a breakout adapter, but Megasquirt obviously doesn't care what the immobiliser says. I can run the car on a copy I had cut (with no chip in it), all that happens is that the immobiliser starts flashing its warning light.
• I haven't been able to get the CEL (1E) to light up, but I may just have wired that wrong and haven't looked closer into it.
• I don't have a rear oxygen sensor, only the front one. Third-party ECU's don't use it anyway, so meh.
• I have the ECU in the passenger footwell. Online sources say that 90-93 Miatas have the ECU in the passenger footwell, 94-97 have it behind the passenger seat.

There may be other stuff I haven't noticed, but everything I needed to actually get the Megasquirt up and running was where it was supposed to apart from the fuel pump relay.