busta9876

I've got a 305 TPI currently with Megasquirt & Spark. I have a 165 ecm laying around I am in the middle of building a wire harness for, and I am going to run the Speed Density 5D code. I already have a MSD Pro billit dizzy and 6AL box that i want to use. I'd just like to use it with mechanical advance and vacuum advance as you would with a carb.

Where would I feed a tach signal to the ECM? Anyone know if the TACH output on the side of the MSD box would work?


Thanks

Brendan.

RednGold86Z

iTrader: (1)

I think it needs a 5 volt signal. Not sure though.

3.8TransAM

The tach output in the side of the MSD box worked for me on my 91's.

I cant verify that it will work on the older setups however.

later
Jeremy

Grumpy

Feed the Point signal to a 1K resistor, and LED. The tie a stock GM ignition module across the LED (ie where the pickup coil would wire in). Then the ecm uses, and thinks it's using the module (since it is).

1/2 the benefits of EFI are being able to more accurately control the timing.
You'll never match the timing with a set of weights and vacuum to what you can do with an ecm controlling the timing.

Deviant7

Grumpy,
I want to use a 165 to control a TBI on a 1st gen rx7, but I cant use the ignition from the ecm.
So i figured if I use the stock distributor, and used the 165 to control fuel id be set.

However I think i am following what you are saying, but im probably wrong.
is this correct below? or should the led and resistor be inline with the VR input. If it goes inline with the VR(P&N right) what do you do with the coil side? Leave it alone so it wont fire anything.

hope this is clear enough, hope to get the rx7 going soon

RBob

iTrader: (1)

Modified the drawing. Need +12 to module to power it up. The 'points' is the tach output. The resistor going to the TACH output and the bottom of the LED going to ground. I've found 2 LEDs in series are sometimes required. Has to do with the voltage drop across the particular LED (they vary).

Can also substitute a 5.6 v (or there abouts) zener in place of the LED.

RBob.

RednGold86Z

iTrader: (1)

A TBI with a 165? I didn't know it was able to do TBI injectors or have the proper "inject on each reference pulse" mode, or every other ref pulse with 2 injectors, I suppose. Can it?