Vehicle Info:

• Year/Make/Model: 1992 Honda Civic Hatchback (EG)
• Original Engine: D15B8
• Current Engine: D16Z6 VTEC (engine swap)
• ECU: OBD1 chipped ECU (Neptune RTP / Demon 2)

Background:

Base ignition timing has been set with a timing light.

D16Z6 injectors are installed.

Original D15B8 fuel rail, FPR, and fuel pump are still being used.

Symptoms/Issues it’s having:

• Tachometer bounces/jumps during acceleration and deceleration only

• Tach bounce is perfectly synced with:
  • sputtering
  • lag
  • misfire
  • backfiring

• Under full-throttle acceleration (especially in 3rd gear):
  • heavy sputtering
  • backfiring
  • unstable RPM

• At ~5,000 RPM in 1st gear, engine lags and backfires
• During light acceleration below ~3,000 RPM, occasional misfire/backfire
• During deceleration, occasional exhaust backfire below ~3,000 RPM
• At steady cruise and idle, engine runs relatively smooth
• Strong smell of unburnt fuel after sputtering/backfire events
• Spark plugs appear dark/sooty and smell like fuel
• Tuning adjustments made the car slightly smoother, but did not eliminate:
  • tach bounce
  • misfire/backfire under load

• Distributor has approximately 180k miles (condition unknown)

Please Let me know what you guys think! Thank you!

 

here is a YT vid