what needs to be hooked up on the ECU just to run spark out of the two plugs for the injectors and sensors? I have a power to a white/blue i think and then 3 or 4 grounds? The plug for the coils and what not is hooked up but when i crank i get no tach pulse. Trying to run MS with fuel only till i get my VR board. thx guys

 

You need the AFM, boost/pressure sensor, ECT, IAT and TPS. Then obviously the CAS and coils.

If memory serves, blue/white is the only 12V power that the ECU needs. HOWEVER, the coils get their power from the front harness so they won't fire unless that harness has power (from the EFI relay).

Note that the ECU will fire spark without most of those sensors, but it will dramatically effect the timing curve.

 

The ecu needs to see all those sensors for just spark? I'm trying to run Megasquirt with just fuel until i get my VR board for ignition. With all the plugs in the OEM ECU i get a nice clean tach sig to the MS, but when i unplug the connector for the injectors and the connector for the sensors but i have the connector for the cas and coils hooked up i lose spark. The coil still has 12v+ but nothing for spark still?

 

pfft, you don't need a CAS signal..

you'd obviously need to split it off to lead into both the MS and stock ECU, or you can just wait until you get what you need and not jerry rig it.

 

the connector for the ignition is plugged into the ECU. Im pulling the tach sig off the test connector the same wire for the tach in the car as if i were running a dizzy for the MS. I dont see how this is jerry rigged? just using stock ignition and running fuel with MS like its an FB. All I want to know is what off the emissions and injectors connectors at the ECU I need to get spark.

 

You confuse me. Look in your local FSM in the FUEL AND EMISSIONS seciton and the pages called CONTROL UNIT. It lists the function of each wire on the ECU.

If you disconnect the small ECU plug you lose all power to the ECU. See the FSM CONTROL UNIT page.

No power to the ECU means it won't pulse a signal to the coils ignitors to cause spark.

You say you have "the plug for the ignition is plugged into the ECU". To me that would be the small plug that carrys power to the ECU and also has the fuel injector wiring. The large plug on the ECU carries the coil signals like the CONTROL UNIT pages say.

Frankly I don't see why you don't leave all three plugs on the ECU. Got me. IF you need wires from those plugs for the aftermarket thing you have, then just depin those wires from the ECU plugs.

 

sry Hailers im trying to run megasquirt with only fuel and use the stock ignition. So sensors and injectors are hooked up to the megasquirt and the plug for the ignition is hooked up the OEM ECU. I used an old S4 plug to ground and power the pins on the OEM ECU that are not there because they are hooked up to the megasquirt. I found out partly from Aaron and rotarygod that u need the MAF hooked up for spark. ive got it hooked up now and im getting spark. thx guys

thread with rotarygod >> https://www.rx7club.com/showthread.p...t=spark&page=2