I have owned my '95 for about a year now but I know almost nothing about it, the previous owner did all the modifications to the car so I only assume what I was told is true.. the only thing I have done is replaced sparkplugs taken it to a reputable miata tuner in my area (DFW TX - Ethan at trackstar motorworks)

The tuner was able to get it to idle, as it wouldn't when I bought it. He did some dyno pulls and was able to get it mostly drivable, but he thought something is wrong with the wastegate. He set the boost controller to 100% and it topped out around 17psi, he thought it should have been more. I have been driving it to work and back once a week with relatively no issue for the past year like this, occasionally it will not start after stopping for gas until it cools down a bit. Over time I started pushing the car a bit more occasionally, and noticed when staying on throttle long enough to hold boost over 12-13psi it starts misfiring/bogging badly. Otherwise the car seems to run perfectly fine.

1995 Miata

Engine

• Bored to 84mm
  
• Forged internals
  
• Volvo valve springs
  
• 640cc injectors dw200 pump
  
• Coolant reroute
  
• Toyota coil on plug conversion
  
• MS3Pro ecu
  
• NB 6 speed trans swap
  

Turbo

• Kraken top mount kit with 3" exhaust
  
• GT2560R turbo
  
• Turbo smart BOV
  
• Forge wastegate actuator - in the spare parts box that came with the car there was 2 other actuators with PN: 448734-5 so maybe the previous owner had a similar issue?
  
• MAC boost control solenoid - tuner originally thought this was the issue, but put a manual one on for testing and had same issue
  

I'm new to the platform, and bought another guys project. I don't know where to start, and I can't really afford to throw parts at the car that won't help the issue. Anybody have any ideas?

 

Hook up a laptop and save the tune without changing anything. Then, press ctrl-L, enter, and drive around with a warm car and make it do the misfire/bog. Press ctrl-K and attach both tune and log here

 

Post the tune and a log of it breaking up. That's an insanely common build so it shouldn't be hard to get it running decent. If a "reputable Miata tuner" couldn't get it running well I'm going to guess there's a mechanical issue, but it's useless guessing without the tune.

 

I added the tune and some log files to the main post, thanks for the help. Also do I need to purchase megalogviewer to view my logs?

 

Yes, you'll have to purchase MLV to view longer logs. It'll cut them off after a certain length if you don't.

Logs are sorta all over the place, you're tipping in the throttle the entire time, so it's difficult to see what fueling is truly doing. The longer log you're quite lean, 12-14 in boost, but the other three you're rich in boost, 10-11s. Spark table is probably 2-6 degrees too advance in most places, and yes, you definitely have an issue if you're only hitting 17psi with a 2560 at 100% DC. There's no real point in tuning above ~80%dc, as it behaves nearly identical to closed (100%). So tapering from 92 to 95 to 96% like yours does shouldn't do anything. Start by checking for leaks.

After all that, I'd be curious what duty cycle your injectors are at. They're in the high 70s without being at red line, the correct AFR, or full throttle, all of which will increase DC, so I'd be concerned they're running out up top. I don't see a fuel pump on your list, I'd highly suggest installing one if you haven't, and/or a fuel pressure gauge logged to the ECU.

EGO disabled, afterstart enrichment is basically disabled at hot temps, that'll help with your hard hot restarts. Idle ignition timing is doing nearly nothing, idle is open loop, basically it looks like it needs a complete re-tune both on the dyno and the street for drivability.

TL;DR priorities:
fix ignition map
check for boost leaks
install FP if not already
log 100%TPS to redline. If boost leaks fixed, remember to lower EBC DC significantly
verify fuel pressure, injector DC, and AFR vs. AFR target is good