MS3X not reading cam/crank signal

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add lightness
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Joined: Sun Jan 17, 2016 1:41 pm

MS3X not reading cam/crank signal

Post by add lightness »

Hi guys, I built a v3.0 MS3/x and installed on my '91 1.6L Miata, entirely stock. Loaded up a base map, it fired right up and seemed to run well. I proceeded to remove the engine and install an engine from a 2001 NB running donor car, and spliced the '01 cam and crank sensors into the factory wiring in place of the 1.6 CAS, as well as all the other wiring changes required for the swap. I changed nothing on the ECU side, other than moving the O2 wire on my adapter harness and adding two wires for sequential injection. I downloaded DIYAutotune's MS3-pro base map for 2001-2005 Miata and changed all settings and I/O to fit my application, to the best of my knowledge.

Now, when cranking, it shows no RPM and doesn't seem to be reading the cam or crank signals. All other sensors seem to be working. I'm inclined to believe it's an issue with the tune in some way, since the sensors are known working and have power, ground, and continuity to ECU, and the ECU ran the previous engine correctly, with no changes done to it since then.

I'll attach my tune and a cranking log (hopefully the one you guys want to see). I tried taking a composite log and got absolutely nothing. If someone would like to take a look at it, that would be awesome. I'm using the mainboard crank input and MS3X cam input. What other info am I missing?
Matt Cramer
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Joined: Thu Apr 16, 2009 8:08 pm

Re: MS3X not reading cam/crank signal

Post by Matt Cramer »

Can you get crank / cam signals if you test it on a JimStim?
Matt Cramer -1966 Dodge Dart slant six running on MS3X
add lightness
MS/Extra Newbie
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Joined: Sun Jan 17, 2016 1:41 pm

Re: MS3X not reading cam/crank signal

Post by add lightness »

Thanks for the reply Matt. I guess this thread took a little while to go through, I just found the issue. R56 was adjusted way wrong, showing only 1.1V at the top of R54. I had dialed in 6 turns CW as suggested by the build guide I followed, but I must've turned it way too far CCW initially (mine didn't click). Adjusted it to 2.75V and am now getting crank signal! Car battery proceeded to die before I made an actual start attempt. Will try again soon.

I wonder what is different about the NA Miata CAS sensor that its crank signal was able to go through with this setting so far off.
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