[Had0uken!]

Guys any help on this:

I've been getting rough/failed starts every morning for the last 2 weeks now. Usually when left overnight or if the car has been stood for 8+ hours on initial crank it will fire up (only a .5sec longer crank than usual) and then idle really badly with the revs bouncing until either the car throws an engine light or cuts out or it starts misfiring cylinders (usually only a single cylinder i.e. cylinder 5 or 6 or i'd get multiple misfire codes for that bank - but only ever bank 2) resulting in it knocking and me shutting it down. once i've done this i can then turn the car off and restart and it will cold start fine and drive smooth without any other errors. Initially i thought injectors but i've changed all bank 2 injectors to new index 12's (and coded them), also had new precat o2 sensors and new sparks all round including swapping coils out with known working ones.

Car previously had mosfet failure before all the rough running issues started on cylinder one so these were all replaced but it's not cold started fine since even though i've replaced plugs, injectors, coils etc. I was thinking it could be HPFP as i've seen a 29F2 code pop up twice but this is usually only if the car is left running for a minute or so AFTER it misfires on a cold start and it has multiple cylinder misfires (its only thrown this code twice in 2 weeks, every other rough start i just get misfire codes then turn off car and restart). I've also noticed that the car backfires when i first get on the accelerator after coasting (not the usual lift off throttle burbles as this is a loud pop and only when the pedal is first pressed or when i'm coasting and put the clutch in as soon as the revs drop to idle it pops).

I initially thought this could be injectors leaking hence the initial rough first start so i've already replaced bank 2 injectors with new index 12's. Pulled plugs after leaving the car overnight and no fuel on the plugs. Other than the popping i get no drivability issues even on a hard pull.

I've got a log below of the failed start - if you select the rpm you can see the 3 times i restarted the car when cold starting until it idles properly. Whenever it misfires and runs rough and the AFR for bank 2 is usually pegged at 10.28 - this to me says it's running rich rather than not getting fuel or could this be because of inadequate fuel pressure the cylinders are shutdown but theres fuel left over? as soon as i restart the car the AFR levels off and it runs fine.



I'm about to order a new hpfp and 3 index 12 injectors for bank 1 but thought i would double check on here. I've also got a video showing the failed start along with the gauges. It's weird how this only happens on bank 2 though. THe mosfet failure was bank 1 but after sorting the mosfets i was consistently getting a cylinder 6 misfire so i swapped coils/plugs and injectors and now i can get the car running and drivable but on cold starts still get rough running from bank 2. Could a HPFP only affect one bank? or could something else in the ecu have gone when the mosfets went?

Video below shows the cold start issues.