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Old 10-26-2008, 05:59 AM   #1
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Default quick question ( newb ) on megasquirt install

Ok so I haven't bought megasquirt yet. I have not even bought a turbo kit yet. But I kind of want to buy the megasquirt and turbo kit the same time on begi. I was reading the manual and it says I need a timing gun. I don't have one. I am not really sure on why you need one I believe it said to make sure the CAS didn't slip. What is the CAS? Is this necessary? Is there any way to get around this? Thank you.
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Old 10-26-2008, 10:40 AM   #2
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CAS = Crank Angle Sensor. Located at the back of the head, turns to adjust the timing. Use the timing light to verify correct settings.

Read this - Miata Ignition

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Old 10-26-2008, 12:22 PM   #3
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Yes, a timing gun will be necessary when you install your Megasquirt for the first time. You will have to adjust a couple parameters in Megatune (MS software) to get the timing set, so what MS thinks it is agrees with what the engine is actually running. Once that's set though, you might not need the timing gun again. They're about $30-40. If you don't want to spend that, try to borrow one from somebody or find an auto parts store that will loan you one for the afternoon.
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Old 10-26-2008, 12:32 PM   #4
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First off, timing guns are inexpensive. You should be able to find one at a local auto parts store or Wal-Mart for perhaps $30 to $40. You don't need any fancy features like dialback. I'm still using a POS SunPro brand timing light that I think I paid about $15 at K-Mart eons ago.

As Vash pointed out, the CAS is what tells the ECU where the crankshaft is in its rotation. Specifically, it sends out a pulse every time a piston is about 60 BTDC (This is a hugely approximate number, and is adjustable.)

Now, it's that adjustability that's the problem. As you read The Documentation you'll see that in the Spark Settings page there is Trigger Angle (deg) field. This is where you calibrate the orientation of your CAS. To do this, you first lock down the ignition advance to 10 degrees BTDC, then you run the engine while observing the crank pulley with a timing light. If the notch in the pulley is not aligned with the "10" mark on the timing strip (and it won't be the first time) then you adjust the trigger angle number to bring it into alignment. Once that's done you set the Fixed Angle back to -10, and now your spark advance tables will be accurate.
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Old 10-26-2008, 05:52 PM   #5
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Ahh I see. Thank you that cleared it up for me very nicely. About how long did the install and setting up the megasquirt take on average?
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