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Old 12-14-2012, 02:21 AM   #1
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Default 2002 Miata - MS3 or 3x?

I bought a MS kit, including the MS3 card but no 3x expansion card, from a board member. He bought an unassembled kit, soldered it himself and could not get it working - he solved his problem with a Plug & Play.

My board appears to have been assembled by combining the instructions for MS2 assembly plus the mods for tach & cam inputs as well as spark outputs from Frank's 99-00 MS2 assembly instructions. Thus, there are components installed for the clock circuit, fuel pump driver and other as well as the Miata-specific input/outputs. It appears that steps 50 & 65 from Frank's instructions were used, but all of the other steps Frank instructed to be omitted were included instead.

There are no alt or VVT control circuits installed.

I want to complete a parallel install to preserve the ability to pass OBDII plug-in inspections in Metro Atlanta. Additionally, I have assembled components to install a small Nissan turbo on the car (the computer install and tuning for stock, then RX8 injectors, will precede any turbo activity).

This computer will go into my son's car and he is past frugal. Thus, while adding the 3x card would be the most straightforward route for me, I would like to avoid the cost.


1) Can I control the VVT with MS3 without the 3x card? If so will someone guide me to a circuit for this?

2) Just for my info - Is the alt control circuit described in Franks '01-'05 PNP build writeup the current preferred circuit? If not will someone guide me to the preferred circuit?

3) Other than the sequential spark & injector capabilities and the ease of setup is there a benefit to using the 3x card that I may have overlooked?

4) For the parallel install am I correct to:

a) share the IAT, CLT, TPS, Cam pos, Crnk pos sensors after removing the pull-up connections from the MS board for each:

b) leave the MAF & stock O2 sensors connected solely to the stock ECU; and

c) cut the injector & spark outputs from the stock ECU.

5) If I use RX8 (~450cc) injectors will the stock ECU handle idle, fan, a/c, alt, & fuel pump control as well as it does with original equipment and setup? If not what mods are recommended to handle changes?

Thanks for advice and references to appropriate reference materials.
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