2.7T APB - misfires cyl 3
 

After engine swap (APB to used APB) and ICM delete (FSI coil conversion), plus new CM FX400 with single mass flywheel, I have consistent misfires on cyl 3. Idle, part throttle.

Only after warm up, there is a very small window where misfire counter stops and engine appears to run smooth: VERY little throttle (-3 to 0 on the boost gauge).

I am at the end of my wisdom after:
- verify spark
- verify fuel
- swapped coils, plugs, injectors
- replace plugs, injectors
- swapped MAF
- swapped MAP
- swapped FPR
- installed fuel pressure gauge
- swapped ECU
- verified firing order (video)
- injector output test
- compression test (all 6 have 170 psi)
- leak down test (cyl 1-3 under 6%)
- valve cover removed, cam chain timing good
- leak test (professional 'smoker')
- pressure test (through MAF to 10 psi on boost gauge)
- throttle body alignment VAGcom
- wire trace coil signal to ECU pins
- wire trace injector signal to ECU pins according to diagram below
- resoldered
- changed wiring to separate ground for coils directly to engine ground
- VAGcom cam timing verified (block 90-93).
- Noid light check of spark signal and injector signal.

Bought oscilloscope to take a closer look at spark signal, cam signal, crank/engine speed sensor signal, injector signal. Can some give tips/suggestions how to use osci for diagnostic?

Any suggestions, tips what might cause the misfires on cyl 3?

Could a lazy valve or lifter on cyl 3 cause the issues (despite good compression and leak down)?

Is it perceivable that the new Clutchmaster flywheel might cause the issue (bad/damaged/dirty tooth on the timing ring)?

Cam sensor? Crank sensor?



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