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thinking about megasquirt


taylor76zharris

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Alright there is 12v to the coil, the engine is perfectly in time, T/S shows 215-220 rpm while cranking but when i used a timing light to confirm spark... nothing, not even anything from the coil to the distributor. The coil is brand new. I even tested it and its fine. 12v to the positive and pin 36 to the negative. I just dont get how the coil can have 12v to it and have nothing come out of it.

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The coil has to have current flow to make a spark. You can have 12 volts available to push the current but if the circuit isn't completed to ground the coil never energizes. Spark is made by making and breaking the circuit through the coil. That's what Megasquirt is supposed to be doing, using the signal from the CAS.

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Did you verify that Q16 is there? Take an ohm meter and ohm pin 7 on the 40 pin cpu socket to the left pin on the bip373. You should have 330 ohms if D14 is your spark output(preferred). You can also ohm the middle pin to the coil neg. and the right pin to ground while you're in there.

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I have ms 2 I didn't build mine but im not familiar with any of things you just mentioned. I have 3.0 board is the 3.57 that different? I suggest you call diyautotune since they built it for you to see if your running the right ignition input for your setup. This is a key step way before tuning and all that.

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And here is the wiring diagram i used to wire in my megasquirt

 

 

MSwiring.png

 

This is how the distributor is wired.

 

280zxt_v3_igbt_wiring.jpg

 

Also Where it calls for 12v from the fuel pump relay, there are two wires that supply 12v on the fuel pump relay but one is switched and the other is constant. Ive been using thte switched one to supply power to the +coil and injectors, not sure if thats the right one. The black/white wire on the distributor is supplied with 12v through a 5 amp fuse. The green/black wire on the distributor is supplied with 12v through a 1k 1/4 watt resistor, pin 24 is also connected to the gree/black wire. The black is grounded. does this seem right or wrong?

Edited by taylor76zharris
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  • 2 weeks later...
  • 2 months later...

Taylor76 Not sure if you ever resolved your spark issue. You say you see it was fried what makes you think that and what have you seen? When DIY did the mod on my 3.57 board i'm pretty they had the spark output come through JS10 not D14 (preferred).  Something to look at.  Might just be a simple ignition setting in tunerstudio causing your issue.

Edited by motomanmike
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  • 4 weeks later...

No, i never got it figured out. I pulled it all out and im just going to start over and really take my time. A small section of the board near Q16 got burnt up but i believe its still functional.

 

Just a refresher. The car is a 78 280 and the motor is an L28ET out of an 81.

 

The car ran extreamly rough when i got it with the stock efi sistem. I thought it was a bad MAF or the fact that it had no O2 sensor on the down pipe.

I got a new O2 and it still ran the same. Never got a new MAF i just decided that megasquirt would be eaiser in the long run and would work better also.

Anyway, While i was trying to redo some of the poor wiring connections is when i did something that caused me to lose spark. I did nothing but put proper wire connectors on in lue of the tape and twist method used by whoever did the swap.

 

So i had no spark before the Megasquirt swap and no spark after.

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If part of your board is cooked near the Q16 thats definetly why you don't have spark.  Q16 is where the BIP373 for direct coil control is.  If the traces on the board aren't cooked too bad you might be able to repair it.  DIY might know a trick to bring that output out of another pin on the DB37 connector to bypass the part of the board that is cooked.  Posting some pictures and your MSQ might be very helpful in trying to figure out what might have caused it or help in fixing it.

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But I had no spark before it started smoking and i also tried JS10 and D14. I had to have had something wired up wrong or some setting in TS wrong, But i was pretty sure the wiring was correct.

020.jpg

 

One more thing, where can i find my MSQ? Is it on the MS ECU or in TS?

Thanks you guys

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