Hi all,
I'm halfway through an install however I'm having a bit of trouble with the wiring side of things and would appreiciate any help I can get.
I've got a V3 megasquirt running fuel and stock ecu for spark on my 88 rx7 turbo series 4. I want to run it like this as I feel a jump to both ignition and fuel maybe too steep a learning curve for me.
The connections I've made so far:

-coolant temp sensor sharing with stock ecu on connector 2I

-Air temp sharing with stock ecu on 2L

-O2 sensor sharing with stock ecu on 2D

-TPS sharing with stock ecu on 2G (5 volt Ref supplied by stock ecu)

-RPM off leading coil connection V

Injectors are primarys on MS pin 32 and 33
secondaries on pins 34 and 35

Does this look right?
Thanks

 

Looks OK. But be sure to have the stock ECU unplugged when using the Mega Squirt. I ran a whole season that way and kept the stock equipment for a back up system. I was not sure if the system would work at the track level but it did. Not perfect but enough that I feel I will run this season with it and take out the stock system this winter.


-coolant temp sensor sharing with stock ecu on connector 2I- Green Wire (DB-37 Pin 20)

-Air temp sharing with stock ecu on 2L- Green White Wire (DB-37 Pin 21)

-O2 sensor sharing with stock ecu on 2D- Add Wire (DB-37 Pin 23)

-TPS sharing with stock ecu on 2G (5 volt Ref supplied by stock ecu) Green Red Wire (DB-37 Pin 22)

-RPM off leading coil connection V - Ba-28 Wire (I ran a separate wire from the leading coil)

Injectors are primaries on MS pin 32 and 33 - (Ba-27 3E Front Primary and Ba-27 3C Rear Primary)
secondary on pins 34 and 35- (Ba-27 3H Front Secondary and Ba-27 3F Rear Secondary)

Run both it will work. The only problem was stabbing the CAS.

Good Luck

 

Thanks SCCA RX7 RACER for your reply. I've wired the megasquirt up exactly as you described however I'm not getting an RPM signal. I've tried tapping into both leading and trailing wires at the ecu plugs and have had no luck. I've modified my megasquirt as per the rx7 club FAQ except for these steps: (as I thought these were for ignition control)

- TSEL to VROUTINV on the inside of the board
- Second VR conditioner

Is this what is stopping the megasquirt from getting rpm?
I plan on using the megasquirt later to control ignition but just want fuel control at the moment.

 

Hi There,

If I was instructed properly before, my understanding is that the fuel timing and ignition timing comes from the Crank Angle Sensor signal to the Mega Squirt. I went with the removing two teeth method on my CAS.

From the DB-37 pin 24 I connected to the BA 28T wire CAS NE+ and DB-7 Ground to BA 28Q CAS NE-.

I mentioned “RPM off leading coil connection V - Ba-28 Wire (I ran a separate wire from the leading coil)” What I was trying to say is it for ignition signal to the coil to fire.

If you’re only going to use Mega Squirt to manage fuel only I’m not sure how to tie it in to operate fuel only and let the factory ignition run spark. I changed over both at the same time. In this way I could isolate both systems and if the Mega Squirt let me down I could always get it up and running. All I do is swap out the CAS and swap over two sensors and hook up my air flow meter. I set it up that I can make the change over in 20 minutes if I had to.