John90_UK

Hi All,

I am new to this forum but have owned my 1990 UK mx5 for 9 years now, and modified it quite a lot with M45, 60/150, chargecooler, HSV WI, 2004 Sport Big Brake Kit, 2004 Mohair roof and heated leather seats, and many other bits and bobs. Management side of things I was originally OEM, then JR CAI, then JR AFPR with Bipes when I fitted the s/c, then EMU then more recently I changed for a Gotech ProX which I had fitted at a garage but didn't turn out well. The car started and drove but idle was unacceptable and there were other issues too. I am therefore now removing this with my brother and fitting a Adaptronic 420C.

We are trying to return the car management back to as close to standard as possible, getting it to run on the OEM ECU before moving on to the Adaptronic install and tune.

Unfortunatly rather than the wiring having been done in the footwell for the Gotech it has been done in the engine bay with the injector harness cut along with many other wires. We have returned most of it back to standard now by reconnecting the wires and fitting the std injectors, flappy AFM, OEM coil pack etc and the only error code from the diagnostics box is for the missing carbon canister.

The car won't start though, it turns over but won't catch and back fires. He's pulled the plugs and they are wet, and has tried using part throttle but still it won't start.

Our first thought jumped to the ignition order but I've double checked the ht lead positions and they're correct according to the workshop manual PDF diagram. I've also dialed the tps to extreames but no change. The wiring to the coil is pretty standard since the engine loom end was untouched as a new loom was fitted to power the presumably ford coil pack direct from the gotech. The other end at the ecu is pretty easy too since it was just a case of matching up the wires from where I'd previously spliced in the e-manage so the low current side (ie not ht) should be fine too.

To address the fuel relay issue , I can't quite see what's happening, there is no additional wires to the fuel pump, and the 'starting circuit relay' operates ok giving power to the pump supply terminal. Then according to the circuit diagram it's just a straight feed to the pump - yet I don't get power to the pump. I have removed most of the dash Inc blower unit, glove box and center console but I can't find any gotech cables running anywhere near that side of the car - odd!!! So i've run a new cable and pump works great just as it should.

The Gotech wasn't installed standalone, the original ecu was just (as far as I can tell) no longer controlling fuel or spark, the Mazda ecu still doing cooling fans, starting circuit etc.

Brother has timed the car to 11 deg BTDC on the starter motor and no difference so still looking for the cause of the backfire/non-starting. Brother has noticed a possible strange wiring colour issue with the OEM coil pack we recieved back which presumably is our original one but can't be sure (Ross has removed the presumably Ford one fitted).

The car harness plugs into the coil pack harness and both have 3 wires.

The wires from the car harness to the plug from the top are:
White
Red
Blue

and on the other side of the plug from the coil are:
Black with white stripe,
White
Red

which seems a little strange possibly? The manual and circuit diagrams don't seem to mention the plug or wire colours either side of it so we would really appreciate it if someone with a mk1 1.6 (if it makes any difference?)could have a look at the wire colours on there's, which should be easily visable we believe.

We have had a look at the CAS sensor and noticed the back is missing off it but since the car ran on the Gotech in this form I imagine the problem is not this.

Another curious bit is that if you do the multimeter testing of the coils we get the manual stated resistance on the secondary windings but the primary windings give 1.5 ohms which is more than the 0.78 to 0.94 ohms (@20oC) stated in the manual, but I am not sure that this would cause the car to not start and just backfire would it?

Any suggestions of what the problem could be or what to do next would be greatly appreciated as we are a bit lost about what to do next. We don't really want to buy replacement parts at random to try as this could get very expensive very quickly!

I was not sure where to post this so I have posted it in the Adaptronic section too but please move as required Mods.

Thanks in advance
John