[a_wolly]

Hi,

I have a 2011 reg F11 (N53B30A engine) with 74k miles, which has been diagnosed with irregular spray patterns for injectors in cylinders 4&6. I'll try to save you yet another thread about faulty/leaking injectors but just for context, the car has typical rough idle on cold start only and fluttering accelerator petal between 2-4k rpm. No misfire errors and no engine warning light. It's already had a full set of index-11 injectors fitted 3yrs (15k miles) ago.

The local indie who spotted the spray patterns (polished areas on top of pistons) said the injectors aren't leaking. I'm not sure how he knows this, though only a month earlier they replaced a cracked valve cover causing an oil leak, so presumably knew the state of the plugs and injectors.

My understanding is that for the rough idle to only happen on cold start they must be leaking but maybe there's other causes for this. In any case, the indie said it's a rare/strange scenario which isn't looking straight forward (- e.g. suggested maybe a valve isn't seated correctly or a compression issue).

I thought I'd get a second opinion from another indie because I wasn't keen on dumping £1k on replacing two injectors (and certainly not £3k on all six) just for it to be something else at root. He suggested that because the injectors have so little miles on them, he thinks the HPFP might be on the way out. He indicated that it's a known issue for faulty HPFPs to create swarf which results in injector failure (amongst other issues).

A third indie then told me they've never heard of swarf causing injector issues in this way.

My questions are:

1. Is it straight forward to DIY diagnose for swarf and/or faulty/failing HPFP to rule that out without ODB software?
2. Has anyone experienced swarf resulting in leaky injector symptoms?
3. Has anyone experienced injectors failing so early in their life without an underlying issue being the cause?

My gut is telling me to replace the two injectors in the blind hope that I just have a couple of duds (or they're simply clogged from the recent oil leak or previous owners using low quality fuel) but my mind is saying walk away before I'm in too deep.