Hope this is good news for you.
I've been tearing my hair out trying to get my stuttering 2.4 fixed to no avail. I noticed months ago that the turbo air intake pipe was loose. I pointed it out to the dealer who told me "they're all like that" and "not to worry".
On closer inspection this weekend, I noticed that there's quite a lot of oil leaking from around this pipe where it meets the turbo (see attached pic). If oil is leaking out, then air is leaking IN. This is *not* good, as it'll confuse the hell out of the mass airflow meter and shutter valve (which will battle together in vain to regulate the incoming air...).
So I thought, what the hell, I'll try a temporary fix with an extra hose clip around the pipe. (standard 50-70mm clip, £1.88 for a pack of 2 from B&Q). Slightly tricky to fit, applied just enough pressure to firmly fasten the pipe.
Result: NO STUTTERING!
I just drove it 200 miles on a mixture of motorway and country lanes and the engine felt great - better than it's done for months! I think/hope I may have fixed it. (Disclaimer before I get too excited: it did still do its "loss of power and stumble" thing for about 5 miles on the motorway - this may be related to the DPF cleaning cycle, so another problem entirely...)
Anyway, to cut a long story short:
- Is YOUR 2.4 stumbling?
- Is YOUR intake pipe loose? (try gently wobbling it or lifting it up and down)
I'd be really interested to know if fixing the leaky pipe cures the stumbling for others too. Please
be careful with that turbo if you do the fix yourself!
If it works for enough people, hopefully we can get AR to organise an official fix.