Stewy323

Hi all.

I'm hoping that this is something very obvious, but I cannot figure out what is happening here by looking at my logs. I am using a basic tune and have attached that as well.
For 4-5 years I have had this setup and it has been capable of pulling runs under 8-10psi boost. However this year once it has been running on the highway for ~10-15 minutes any amount of boost higher than ~3-5psi makes the car quite sputtery, it feels like fuel is cutting in and out or something else. I would almost say that the car backfires, but it's not quite that loud, although with the hesitation you can hear a terrible blubbery noise from the exhaust. When this happens the car doesn't end up spooling up much more, but it can still accelerate.

The problem seems a little less severe before it's really warmed up, that is the first few runs seem normalish, but then the issue starts creeping in and gets worse and worse.

I've tried:
-Replacing the stock ignition coil with a DELPHI GN10771
-New spark plugs
-Gapping spark plugs to .020 from the .028" that I used to run
-Tightening all boots on turbo / inner cooler
-Eliminating boost controller
-Visually inspecting turbine in turbo for slop

At this point I'm not sure what to look at next. I'm going to pull the injectors tonight to see if maybe something's plugged one of them up that shows up under higher fuel demands, but I'm guessing that's not the issue.

I captured a brief log of when this problem was happening. Maybe someone who knows more about the megasquirt logs can take a look and find something in there that I can't see?


93 Miata, 1.6L engine.
Greddy turbo / intercooler
Megasquirt Gen2 PNP
640cc Flowforce injectors
OEM-Type ignition coil.
1 year old (300 miles on them) spark plug wires from Napa
New NGK 4644 spark plugs gapped to .025