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Old 08-31-2008, 12:47 AM   #1
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Default a few more MS/LC1 questions.

First of all, on a 1994, I do not have to pull or do anything with the igniter correct?

For my LC-1, It seems there is not enough outputs for a gauge, the MS and the for the stock ecu to be happy. Is there any way around this?

Lastly (for now) Has anyone bought the ebay Serial to Usb adapter and still have the drivers?
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Old 08-31-2008, 12:53 AM   #2
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What do you mean pull or do anything with the igniter? No matter what if you're burning firmware you pull that bitch.
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Old 08-31-2008, 01:00 AM   #3
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What do you mean pull or do anything with the igniter? No matter what if you're burning firmware you pull that bitch.
Ive read everywhere that i have to pull that fuse, but then everyone else is saying on a 1994+ you dont need to worry about anything.
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Old 08-31-2008, 01:04 AM   #4
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If you read the MSPnP manual for a 1994 it says you must pull the iginiter. Also it's not a fuse, it's a connector at the back of the intake side of the engine. The MSPnP manual has a pic of its location.
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Old 08-31-2008, 01:14 AM   #5
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Yeah perhaps you are pulling the fuse that kills power to the ignitor? I personally would unplug the igniter so you KNOW it's not gonna fry when burning firmware.

Not 100% but IIRC the MS can read the same signal the guage reads. MS is adjustable. You just specify the voltage and AFR's. ( ex. 10:[email protected] 20:[email protected]).
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Old 08-31-2008, 01:43 AM   #6
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First- we seem to confusing "the fuse" and the igniter, and misunderstanding the purpose of pulling each.

In the '90-93, the "ST SIGN" fuse must be permanently removed if you are using an MSPNP. This is due to the rather unorthodox (and clever) method they are using to cheat and make the fuel pump work, as in these cars the fuel pump was not originally controlled by the ECU. They're actually back-feeding power into a certain part of the starting circuit which happens to also hit the FP relay. This applies only to '90-'93 cars using MSPNP. Other years, or those using regular DIY megasquirts, need not pull this fuse.

For all years, you must disconnect the igniter(s) when performing a firmware update to the MS, regardless of whether it is an MSPNP or a regular DIY MS. In '90-'93, the igniter is a separate unit on the right fender well, with one large connector. In '94+, the igniters are built into the coils, so you must disconnect the two 3 or 4 pin coil connectors. The reason for this is that while MS is taking a firmware download, the pins which drive the igniters float high and stay there. If the igniters are left connected and powered on during this procedure, they will burn out. Yes, this even applies to COP.

In all Miatas, power to the ignition system comes from the same fuse that drives the main relay and supplies power to the ECU. Since most of us take power from this line to drive the MS, there is no fuse that you can pull to depower the ignition while still leaving the MS online and able to take a firmware update. There is no alternative to disconnecting the igniters, other than removing the wires which connect the two ignition trigger outputs of the MS to the factory harness, which is generally much more difficult than just popping the two connectors off the coils.



The LC1 has two analog outputs, both of which are configurable. You could set one up to wideband mode and parallel it to both the MS and the gauge, and set the other to NB mode and send it to the stock ECU. Or, you could just leave the stock NB in place to drive the stock ECU until such time that you man up and go full standalone.

Quote:
Originally Posted by jobamo
Has anyone bought the ebay Serial to Usb adapter
"The" ebay adapter? As if to imply that every single one of the hundreds of eBay vendors who sell a USB-RS232 adapter all sell the exact same one? Dude...
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Old 08-31-2008, 02:18 AM   #7
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Quote:
Originally Posted by Joe Perez View Post
First- we seem to confusing "the fuse" and the igniter, and misunderstanding the purpose of pulling each.

In the '90-93, the "ST SIGN" fuse must be permanently removed if you are using an MSPNP. This is due to the rather unorthodox (and clever) method they are using to cheat and make the fuel pump work, as in these cars the fuel pump was not originally controlled by the ECU. They're actually back-feeding power into a certain part of the starting circuit which happens to also hit the FP relay. This applies only to '90-'93 cars using MSPNP. Other years, or those using regular DIY megasquirts, need not pull this fuse.

For all years, you must disconnect the igniter(s) when performing a firmware update to the MS, regardless of whether it is an MSPNP or a regular DIY MS. In '90-'93, the igniter is a separate unit on the right fender well, with one large connector. In '94+, the igniters are built into the coils, so you must disconnect the two 3 or 4 pin coil connectors. The reason for this is that while MS is taking a firmware download, the pins which drive the igniters float high and stay there. If the igniters are left connected and powered on during this procedure, they will burn out. Yes, this even applies to COP.

In all Miatas, power to the ignition system comes from the same fuse that drives the main relay and supplies power to the ECU. Since most of us take power from this line to drive the MS, there is no fuse that you can pull to depower the ignition while still leaving the MS online and able to take a firmware update. There is no alternative to disconnecting the igniters, other than removing the wires which connect the two ignition trigger outputs of the MS to the factory harness, which is generally much more difficult than just popping the two connectors off the coils.



The LC1 has two analog outputs, both of which are configurable. You could set one up to wideband mode and parallel it to both the MS and the gauge, and set the other to NB mode and send it to the stock ECU. Or, you could just leave the stock NB in place to drive the stock ECU until such time that you man up and go full standalone.

"The" ebay adapter? As if to imply that every single one of the hundreds of eBay vendors who sell a USB-RS232 adapter all sell the exact same one? Dude...
Thank you so much for clearing everything up!
So it IS okay to have 1 output wire powering both the MS and the gauge, would it still be accurate?
By the adapters, it all seems to be made by 1 company so i suspect they all the same, but to make it more clear, anyone have drivers for this guy



Im sure ill have a bunch more questions tomorrow when i finally install this thing.
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Old 09-01-2008, 12:05 AM   #8
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Quote:
Originally Posted by jobambo View Post
Thank you so much for clearing everything up!
So it IS okay to have 1 output wire powering both the MS and the gauge, would it still be accurate?
If using the XD16 (digital) gauge, it communicates serially with the LC1, so no analog port is consumed.

If using the cheaper DB or G series analog gauges, I am assuming that it must be a high impedance load, so the parallelling should work. You'll have to calibrate the output for what the gauge wants (7.35 to 22.39) and then scale the MS input appropriately.

Quote:
By the adapters, it all seems to be made by 1 company so i suspect they all the same, but to make it more clear, anyone have drivers for this guy
Look on it for anything resembling a chipset id, and then google it.

I bought mine open-box from Fry's for $5. On the back, it had a little sticker that said GUC232. I typed that into Google, and within ten minutes found the driver.
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