KMiata Kpro low voltage & misfires

[John K]

Hello, I have a recently built K24A swapped miata running KPro v4, which is misfiring at high rpm and load. It initially ran fine and started sporadically misfiring at high rpms, but now it does it all the time when pushed. If I persist it throws a P0336 fault code (crankshaft position sensor). I tried changing that with a spare but the problem remains. On throttle I noticed that the BAT voltage on KPro drops significantly, as low as 10-11V, so I assume the problem is there.
The actual battery voltage does not drop, as it stays around 13-14V in all driving conditions when measured with a multimeter. All grounds have been checked, coils and battery have been swapped. I have attached some log files. Any advice would be appreciated.

John

[Spunkster]

The voltage is very choppy and is dropping too much. You need to determine why it is doing this at the ECU if it is ok at the battery. There may be a wiring problem between the battery and the ECU.

You can also try your ECU on a known working vehicle and see if it runs properly to rule out an ECU problem.

[Davidss]

I have a k24z miata with a pro v4 and am using the kpower wiring harness. At first the car was fine but as time went on for longer races it would start to misfire and throw a p0336 code and I think additionally a p0344. I replaced all of the sensors with new OEM ones, checked and added grounds but nothing seemed to help. I was leaning toward thinking it was a bad ECU but after seeing this maybe it's something with the k miata harness.

Hopefully John K has post notifcations on because I am too new on the forum to DM him maybe he will see this and chime in with any updates.

Edit - found another k miata with the same issue: https://www.miataturbo.net/build-thread ... 885/page3/