Intermittent Idle Misfire - cylinder 1
 

In need of help from Miata Nerds!

Problem - intermittent misfire at idle, cylinder 1 is the culprit. high Kpa around 37-45. AFR does not stay stable.

Car: 1993 California emissions NA Miata.
2002 VVT swap
MS3Pro
Running sequential inj/spark
Built bottom end/head
Kraken turbo kit
Flowforce LS ignition Coils
ID 1050x injectors
350lph Fuel pump
Other high hp engine mods etc.

What I’ve tried

• Changed spark plugs 3 times
• Compression test
• Checked valve lash
• Tested coils and injectors through tuner studio
• Swapped around coils and injectors. (Misfire stays on cylinder 1)
• Checked crank sensor
• Checked timing
• Checked injector wiring
• Checked coil wiring
• Swapped fuel hoses
• Checked jumpers in ECU
• Sprayed brake cleaner around to check for vacuum leaks

So I’m not a tuner but my tuner remotes in, when he adds fuel increase to cylinder one, the car idles better and the Kpa settles around 30.

We have really tried everything and it is still misfiring.
I’m looking for as many opinions as possible, any ideas would help.
Thank you

did you ever find the issue?