Wingman703

Well my battery voltage does drop all the way down to 5-7V when cranking. Returns to 13V when not cranking. It's a pretty dead battery jumpered to a strong, charging battery in a running car. I figured the drop was normal due to load. I've seen some weird battery related issues before but not exactly like this. Possible that the amp load on the single good battery between the running car and starter is too great? Try throwing a new battery+jumpers at it? I'm at a loss at this point so I'm willing to try about anything.

sixshooter

iTrader: (12)

Something is wrong then. I'd clean all of the positives and grounds, including the connections at the main fuse and the alternator positive terminal.

gooflophaze

You're losing sync - reasons 31 and 32. https://www.miataturbo.net/megasquir...reasons-43775/

Have you twisted any of the trimpots on megasquirt?

Wingman703

The battery that is in there is pretty dead and has been dead for awhile. I would have needed a new one anyway. Looking at previous logs voltage drops about 2-3v more than "normal". I'll clean everything and throw a new battery in there to remove both possibilities.
Is this not due to cranking inconsistencies? Every cranking/initial running log has 1-2 loss of sync counters, all of them when cranking, none when running. I have not adjusted any trimpots inside the MS.

gooflophaze

It happens, but it shouldn't be happening this frequently / consistently in the MS's I've poked. Check your sensor spacing, and maybe tweak the trimpots. Also, what side of Atlanta are you on?

gooflophaze

Ah - you've also changed your edge detection from falling to rising. Change that back before fiddling.

wherestheboost

iTrader: (-1)

You're losing sync because the voltage is dropping below 6V. Ask me how I know. Essentially there's not enough power to run the MS.

Yeah that's a dead battery. Mine was doing the same after all the failed cranking tests. Would drop all the way down to 5.6V. Swapped to new battery, reset to basemap values for cranking PW, car has started each time.

Swap to new. Try again.

New battery starts at 12ish, and drops to mid 9s at the lowest now. First crank started at 12.1 and pulled down to mid 8s. After that always mid high 9s now that the car is in use.

Wingman703

East side, Stone Mountain area.
Makes sense. This battery was starting to lose its charge ~2 months ago, then sat for a month, then was repeatedly drained by me cranking with it. I figured letting it charge for an hour or so might revive it but apparently not.

gooflophaze

Snellville. Let me know if you need a hand. And change your edge detection from rising to falling.

wherestheboost

iTrader: (-1)

Yeah I had jump started it and drove for 1.5 hours or so.. Too far gone it seemed. Good luck!

Don235

Yes, please replace your battery, I have a 280zx with ms2 and we got it running and driving and then it was harder to start and when it was starting it was doing wierd things( like when I press on the brake it goes MASSIVELY lean and would kill the engine) I put a new battery in it and all those problems stopped.

Wingman703

Fresh battery and jumpers, shiny clean grounds, and a fixed AFR readout. No change to attempted start, does the exact same thing as before. It just can't push past ~300 RPM to fully get going. I have all the ingredients but can't make a cake. WHAT IS WRONG??????

lsdlsd88

https://forum.miata.net/vb/showthread.php?p=9199581

Wingman703

Completely irrelevant as that's a 1.6 and I'm only dealing with 1.8's here.

lsdlsd88

ok so you know for sure the 1.8 manifold does not have a similar arrangement. how would explain your map behaviour from post #10 then?

Wingman703

No idea, and no longer an issue as that port is now plugged and vaccume line is T'ed into the FPR vacume line. KpH readings are normal afaik, fluctuating from 94-80kph while cranking.

For my own sanity I compression checked the motor. Completely cold, 1-4 I got 180, 180, 180, 160. Perfectly reasonable for a 128k mile OEM motor with 80+ track hours and three over revs.
I jumperd GND/FP and confirmed I had fuel pouring into a bottle. Pump is strong.
I have fuel. I have spark. I have compression. It has to be some tune issue.

gooflophaze

You do not have full sync. Assuming that log was a continuous crank, you only have one of your crank or cam sensor responding. Need a tooth log.

wherestheboost

iTrader: (-1)

^^^. You're getting ~30 lost sync events during that cranking attempt. Check the gap on your crank position sensor. Need ~1 credit card's gap in between. It has a tendency to loosen at times. And check cam sensors as well. And also, do what goof says.

Wingman703

Crank sensor gap measures at exactly .53mm, within spec. I know the wiring is good, did it myself. Unaware of any methods to bench check eather sensor. I'll try replacing both.

wherestheboost

iTrader: (-1)

Run a composite log before you do anything. Check to see the condition of the trigger wheel while you're at it.