Megasquirt question.

[R/Tony]

Hi Guys...

Im about to finish my MS installation, everything is already connected and seems to be working normally, but I just have a questions about the spark signal, I just need this and my car should be running the next week

Heres my setup:
2.5 turbo
8 valve.
normal (most recent) hall sensor
Megasquirt I V3.0

Heres the deal:

Acording the GUISDSM in the post #92: possible Megasquirt and EDIS kit: who is interested?

I should be add a resistor between the 12+ voltage and the signal wire of the Hall sensor.

And then he says : "Dont forget to put a 1k resistor between +5V and signal pin." -.. which 5v cable ?... is there another cable from the hall sensor which could give me 5 volts ?

I drew a diagram of what I understand of this:


My MS ECU is already modified for the HALL sensor pickup... but Im not sure how is the wiring to the Hall sensor to the MS and the coil to the MS.

Please help me guys, I can try every possible setup, But I dont want to smoke my MS

Any help will be appreciated. Thanks.

Tony.

[R/Tony]

hehe I know my drawing its freaky... but c'mon I think I just need a yes or no. and why

[90TurboVan]

You cannot run the HEP at 12 volts. You'll fry it quickly or instantly; the stock system is 8 volts, and they work fine with 5 volts. Everything else should be right as long as you've filled in the missing tooth in the distributor, or you can just get a TBI dist as they don't have the missing windows. They also only have one HEP output, which would yeild a cleaner install. I can't vouch for the pinnout on that connector, but if you look at the wiring on the car side, Orange is +8 volts, Black is ground, and Tan with a tracer is signal.

Just to review, you put the + wire from the sensor to 5 volts out from MS (I think it comes out on the 37 pin connector?), a 1k resistor from that 5 volt line to the signal out form the HEP, and the remaining pin to ground.

You should also have the ignition coil + switched by the ASD relay, should be on the same circuit as the fuel pump. Make sure you set base advance with a timing light before doing anything with the MS timing maps.

[R/Tony]

Ok I got it...

heres my new diagram:



the coil is fed with the Fpump relay 12v, and the negative side goes to the PIN 36 of the MS.

The Hall sensor signal wire goes to the PIN 24 of the MS.
The 5v voltaje source is for the HALL sensor.
The negative is the ground.

a 1k Resistor is connected between the signal wire and the 5v source.

finally its ok ?
Tony.

[90TurboVan]

Looks good. If you were so inclined, you could cut the #1 tooth off of the distributor wheel and run MS in 4-1 missing tooth mode with a Neon coilpack.

[xrattiracer]

looks good, but as mentioned megasquirt already provides a 5 volt source. from looking at the diagrams on their site, it looks to be pin 26.

[90TurboVan]

I know I suggested using that source in my first response, but you're much better off getting a simple 7805 voltage regulator and wiring it into the harness. If you were to have a short on the 5 volt power supply line to ground, the regulator in MS will die, allowing full battery voltage through and destrying pretty much every chip in the box. If you have a short with an external regulator, you just fry that regulator and possibly the HEP.

7805's and filtering capacitors can be had from radioshack, and are wired as described here: Simple 5V power supply

The above circuit could just be soldered directly together and wrapped with electrical tape to become part of the wiring harness. Ensure none of the pins can short on the regulator and capacitors. Heatsinking will not be needed, HEP takes current on the order of milliamperes.

[xrattiracer]

wtf? just make sure the wiring is correct and do it the right way; thats why the 5v is provided by the computer. its already coming out into the harness for the tps anyway.

[90TurboVan]

I've learned the hard way several times that even if you know you've done everything right, stuff happens. Even if all the wiring is done right, what happens years down the road when a wire rubs or gets chewed through? I'd use the external 5 volt supply for the TPS too. Cheap insurance that you won't kill the MS.

Or put a 10 ohm resistor in series with the TPS and HEP, to limit the maximum current draw from there to 1/2 amp.

[R/Tony]

K .. I got it , I think I will add a regulator to get the 5v source outside the MS

Ok, and for the initial timing ?.. I think I will need to set the engine in TDC and rephase the distributor ?

Tony.

[R/Tony]

Got the car running

... I have used the TPS 5v signal and seems to be working fine...

But I have a problem, when the car goes near to 4000RPM's automatically the main fuse(10amp) gets smoked, I think its due to the signal cable that is near to the coil wire but im not sure ... any experiences with this ?

Thanks.

[90TurboVan]

What does the "main fuse" power?

[R/Tony]

Its the fuse right next to the 12v source... in the Main relay... its a 20A fuse.

[87turbodance]

Quote:

Originally Posted by 90TurboVan Looks good. If you were so inclined, you could cut the #1 tooth off of the distributor wheel and run MS in 4-1 missing tooth mode with a Neon coilpack.

Is this something that has been proven to work? The dist will run at half crank speed - I thought a 4-1 wheel had to be on the crank

[shadetreeshop]

I know if your running low z injectors & settings in the MS are not correct for pwm you can smoke injector fuses @ higher rpm's ,
higher rpm=more B+ supplied to injector for longer= more fuel.

(90turbovan) Get in touch with me .

Jeremy.