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Megasquirt wiring question...


jacob80

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That being said, where will the other wires off the distributor go since we're not using the GM HEI module?

 

Did you read my post?

 

Also, where can I find the appropriate resistor? Will the stock due fine? If not, can someone link me to one? Thanks again guys!

 

What is this the resistor for?

 

Also, fast idle is not necessary, correct? Just an accessory, correct?

 

That question is for you to answer, do you want fast idle or not.

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In your case you need three things to fire the spark plugs: a coil, a coil driver, and a distributor. The 83 turbo distributor does not contain a coil driver, therefore you need to supply one (either HEI module, IGBT transistor inside a v3.0 megasquirt, or some other ignition module like MSD). Becuase you are using v3.0 you will not need a GM HEI module.

 

Wire everything like the last picture you put up. But remember that two more wires from the 83 distributor need to be connected to the car. That is what the schematic above was showing. The black wire from the distributor connects to ground, the black with white stripe from the distributor connects to 12 volts. The wrie colors at the distributor change once you get to the first wire harness plug. The change is listed in the installation sticky, so make sure you know which side of the harness connector you are on when wiring up the distributor.

 

For the injectors, if you are running high impedance injectors then you can wire just like the last picture. If you are running low impedance injectors and pulse width modulation then you can also wire just like the picture. If you are using low impedance injectors but no pulse width modulation, then you need to wire resistors in for the injectors. There is a diagram in the sticky showing how to wire the resistors if you need them.

 

Ok, so only three of four will need to be connected in my case, correct? The green/black to the relay board, the black to a ground, and the black with white to a constant 12v source? Will a wire directly off the battery be sufficient to the distributor?

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Ok, so only three of four will need to be connected in my case, correct? The green/black to the relay board, the black to a ground, and the black with white to a constant 12v source? Will a wire directly off the battery be sufficient to the distributor?

 

Yes that is all correct. And the green/black wire needs the resistor to 12 volts (resistor A) as your picture shows. You can buy that resistor at radio shack or on the web from digi-key or Jameco.

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Yes that is all correct. And the green/black wire needs the resistor to 12 volts (resistor A) as your picture shows. You can buy that resistor at radio shack or on the web from digi-key or Jameco.

 

Ok, well my question is can I use my stock ballast resistor off our 240z? It looks like it T's off the wire from the wire that runs from the distributor to the relay board....I know that there is a switched 12v source on the car now that goes directly to the resistor, so I assume I can just put a wire on the other end of the resistor and T into the relay board to distributor wire, correct? I think I'm making this harder than it has to be....just basically follow the diagram. I just want to see if the stock ballast resistor on our 240z works. Thanks, without you guys, I would be nowhere, I am very appriciative for what you guys do, and I owe it to you guys, thanks a lot.

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If your question is if you can use the ballast resistor in place of the resistor in post 14, the answer is no. Ballast resistors are typically only a few ohms and you need one around 1k.

 

As for a power source for the dizzy, why not pull power from the MS relay board? In general, it's a good practice to pull power from a single point and also tie grounds to a single point. I don't see why you couldn't use the hot side of the ballast resistor, but since you have to pull a wire for the trigger signal anyway, why not pull all 3? Troubleshooting later will be easier too as you're not relying on the factory wiring which after this much time and previous owners may not be in good condition.

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Anyone?...

 

Something to remember when you make posts like this is that a lot of us have jobs, families, etc. We don't camp out on the forum all day/night long.

 

I would use a coil off an turbo car at the very least. I would remove the ballast resistor and connect the two wires together so the new coil has full battery voltage. You can connect into this wire for 12 volt switched supply to the realy board or other things (like the distributor power wire).

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Something to remember when you make posts like this is that a lot of us have jobs, families, etc. We don't camp out on the forum all day/night long.

 

I would use a coil off an turbo car at the very least. I would remove the ballast resistor and connect the two wires together so the new coil has full battery voltage. You can connect into this wire for 12 volt switched supply to the realy board or other things (like the distributor power wire).

 

Will an MSD Blaster 2 coil be sufficient? Also, where does the ballast resistor play into the new wiring, or does it? I know I will need a 1k ballast resistor, but what is the old one?

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An MSD coil would be just fine.

 

The old ballast reistor is not used anymore, it was used on the 240 z to lower voltage to the coil. Remove it and connect the two wires that went to it together.

 

The new 1K resistor you need would be termed as a "1k pullup resistor". It serves a different function than the old ballast resistor.

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An MSD coil would be just fine.

 

The old ballast reistor is not used anymore, it was used on the 240 z to lower voltage to the coil. Remove it and connect the two wires that went to it together.

 

The new 1K resistor you need would be termed as a "1k pullup resistor". It serves a different function than the old ballast resistor.

 

Ok, so that "pullup" resistor is the one that T's off the wire that goes from the distributor to the relay board, correct?

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alright, I think I've got everything down. How can I pull power from the relay board for the dizzy? Is there a pin that isn't labeled that is a 12v source when the key is on on the relay board? I figured the switched 12v that was used to supply power through the ballast resistor on the old setup could be used as the switched 12v source on the diagram and wouldn't that supply power for the dizzy as well since it T's off one of the distributor's wires? Thanks again guys!

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Use any one of the 4 screws on JP2 which provides +12V to the injectors. You should have at least one of them unused. BTW, you might want to find a place to mount a terminal strip so that you can also power the O2 sensor and calibration switch the same way. Here's a picture of how I did it. You might also want to search for a thread cygnusx1 started when he did his install. His was similar and might give you some more ideas.

 

BTW, make sure you are labeling the wires. If/when you have to go back and troubleshoot you'll be glad you did.

P1000567_1_thumb.JPG

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Use any one of the 4 screws on JP2 which provides +12V to the injectors. You should have at least one of them unused. BTW, you might want to find a place to mount a terminal strip so that you can also power the O2 sensor and calibration switch the same way. Here's a picture of how I did it. You might also want to search for a thread cygnusx1 started when he did his install. His was similar and might give you some more ideas.

 

BTW, make sure you are labeling the wires. If/when you have to go back and troubleshoot you'll be glad you did.

 

Hmmm...not sure what a jp2 is, or why I need another terminal strip if I already have one on the relay board. Also, isn't power on the jnjecyirs only hot when they are fired? Also, what is a calibration switch?

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Ok, for the third time within this thread I'm going to point you to the diagram in post #14 for how to connect the dizzy to the relay board.

 

Side note: I'm frustrated that you continue to ask questions without making an effort to answer them yourself with what's available on the megasquirt site or even what's already been posted to this thread. I'm going to step away from this thread for a while and leave it to others to answer your questions if they want.

 

Edit: the answer to your question about pin 15 is yes, that's the pin that connects to the dizzy signal. What other pin could it be?

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