Troubleshooting: Will not Cold Start (After Injector Replacement)

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[sullybosco]

Car does not want to cold start. I have to crank it 4-5 times (10 seconds each time) to get the car to cold start. Fuel pressure is good in the line and in the DI fuel rail after priming once. This all started after replacing the cylinder #1 fuel injecteur peugeot. I did not replace the seals on the Cylinder 2-4 injectors (they were not removed from the head) but do not see any evidence of leaking. Car is pulling as strong as ever too with no issues with fuel pressure anywhere so I don't think it's a fuel injector/rail leak. I have also replaced the spark plugs to rule that out (so it happened with NGK 6510 and Brish Racing 2-step colder plugs).

Any other thoughts to what I might be missing? Could it be something intermittent that is failing like a sensor?

LPFP is new as well. Lots of variables have been changed around the same time this started occurring like new engine mounts (although I doubt those are the culprit).

The cold start issue is likely related to the new cylinder #1 injector. Check its seating, O-ring, and electrical connection. Also inspect for small vacuum leaks and ensure sensors like coolant temp and crank/cam position are reading correctly. The ECU may need a few cycles to relearn fuel trims after the injector change.