Crankcrankcrankcrank... '99 n/a MS3 - No Start
 

Trying to get my car fired up on a Brain-built MS3. No RPM signal, it just cranks and cranks and nothing happens. I've screwed with a few things (injector size in the pre-loaded tune was set to 420cc or something like that), but still not getting anywhere. What glaringly obvious thing am I missing? The car is a '99, 84mm/8.6:1, stock fuel and spark. Crank sensor is where it needs to be, and this ECU has been back to Brain for some tweaks to correct stuff the PO messed with. I *think* the board and harness are good. I did add a knock module, following DIYAutotune's instructions.

MSQ and startup log are attached.

Use lube please.

You ain't got no synch!
Next step is to take a composite log and post it here.
Set Spark Mode to "Log crank&cam", make sure to power-cycle the MS, then record a composite log under the "diagnostics and high speed loggers" tab.

Here ya go!

Hang on... it's uploading weird

this should work

Your MS doesn't see the crank trigger. Did you set up R56 as per Braineacks instructions?

The documentation I have for my MS doesn't mention R56. I bought it secondhand, and the instructions forwarded to me are from 2012... This is what I've got

Try this (not 100% sure if this is correct, but give it a go): Turn R56 about 12 turns to the fully anticlockwise position (you may or may not feel a “click”) and then turn R56 back about 6 turns clockwise.
Then take another composite log and see if it shows your crank signal.

Silly question, how will I know when it's at the fully ccw position? Does the pot just stop moving once you've spun the adjustment screw past a certain point?

Adjusted r56.... spun the screw ccw 12+ turns, didn't hear/feel a click. Then went back cw 6 turns. Attached is resulting log, still no start

There is no endstop on the pot. So you did that right.
Still no crank signal. I suggest you check the wiring. Again, I'm not 100% that my setup instructions for R56 are correct for a brain-built unit. But if they are you probably have a problem with wiring.

If it's easy enough, you could swap the crank and the cam signal wires- that would tell us if the problem is in the MS or in the wiring.

*Nevermind, you already said crank sensor is in the right place.

I have more luck turning the pot more like 7.5-8 turns try another (2) CW turns on it. Make sure R52 is spun at least (12) CCW.

double check the sensor is definitely positioned correctly.

Thanks for the reply. I'll give the pot another 2 turns this evening. Crank sensor is tightened up snug to 1mm of feeler gauge shims off the tooth.

No dice. Turned R56 two more turns CW and backed R52 off 12+ turns CCW. Most recent composite log and tune attached.

Ignore that last log, my dumbass left the O2 output unplugged.

Still no crank signal indeed.
Can you switch cam and crank signal? That would give us a pointer where the problem is.

Yep... getting to it. Opened up the MS and looking through everything to see if anything stands out to me. It all appears as it should to my novice eyes, and I have continuity across the harness for both crank and cam. I'll crimp on some connectors to the cam and crank wires in a moment here so I can flip em.

Just one thing that may have slipped through the cracks- what is your spark mode in TS set to currently?

As requested, cranking with cam and crank wires flipped

It's set to Miata 99-05

Should I be in "log crank and cam" for every datalog? Just realized I switched it back to Miata 99-05 and kept it that way for the last log

Flipped it back to Log Crank and Cam

Sorry- you're OK being in 99-05 Miata. I was just making sure you didn't try something weird there.

sensor works, but the signal wire going back to the MS seems to be the issue -- pin 24 on the lower DB37.

Your wiring from the sensor up to where you switched the signals is OK. Assuming you switched signals before it hits the DB37.
So now it's either a bad connection in the DB37 as Brain already said, or it could still be something wrong inside the MS3. Could be a cold solder joint on the connector (DB37) on the mainboard, or, more likely, the jumper on the board (I believe it's T_sel).

Edit: Don't forget to swap the wires back!

Board looks good to me. Have continuity across the crank wire on the harness
https://cimg2.ibsrv.net/gimg/www.mia...4c26852ea6.jpg
https://cimg3.ibsrv.net/gimg/www.mia...ab98489742.jpg
https://cimg4.ibsrv.net/gimg/www.mia...a6c66a5a16.jpg

Then I'd give R56 another turn or two. Total of 10-11 turns. Make sure again that R52 is fully CCW.
Do you have a pullup for R45 (an additional reistor connected to the right side of it)?
Are you sure that's a brain-built unit? It doesn't quite look like his handiwork.

Pullup is there. Two additional turns on r56 didnt do it. Fairly confident this is truly a Brain-built unit. He took it back for additional work after the PO connected us. https://cimg3.ibsrv.net/gimg/www.mia...03c66aa55a.jpg

Sorry- that's all I got. Over to the Brain. Pinky out.

i still think there's a break between the sensor and the MS input.