Apologies for the long post...

:confused:

I've got a (coil? DV? MAF? Plugs? Aaarghsomething!) problem with my Octy.

The problem (This is on a completely standard 2001 Octy RS... currently done 32k.)

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Started with about 17k on the clock (18 mths or so ago) as a very intermittent, very slight 'stutter' in the power take up - usually occurs somewhere between 2500/3000 rpm.

By slight stutter I mean fraction of second and less than the TC would do on a damp road when being leadfooted.

By intermittent I mean not even once a day at first (typical day = about 60 miles).

This happens without TC on and in situations you wouldn't expect TC to be kicking in.

Also happens with TC on but you get no blinky light.

Anyway, I'm fairly sure it's not TC related.

Wasn't a big deal really at first but I mentioned it at both the 20k and 30k service anyway.

Dealers were helpful but found nothing - well at 20k they found a fault code but as they said it was nothing related and they'd cleared it I didn't pursue it.

The code hadn't re-occurred at 30k service.

Took it back to dealers about 6 weeks ago as it seemed to be getting a bit more persistent.

Dealer still couldn't find anything (hardly surprising I guess, intermittent faults are a real pain and of course the car behaved perfectly all the way there)

Over the last month or so, it's got gradually more persistent - several times a day but still not predictable as it might go a whole day or two without problems.

Over the last few days, its got much more noticeable.

Also now occurs at higher revs/speeds too (That might be in conjunction with changing up the box, haven't pinned it down yet).

Also when cold and at idle the exhaust note has now developed the occasional 'sputter' to it.

Also, at idle revs hunt up and down 100 rpm or so almost constantly now.

Fuel economy has also dropped from around 34mpg to around 28mpg over the last few weeks but my driving pattern/style hasn't changed noticeably.

Well, not enough to account for that kind of drop I'm pretty sure.

Additionaly - it might be a red herring, but over the last (several) weeks occasionally when starting from being stood overnight car starts fine but

for a few seconds there's a noise from the engine area that sounds a bit like gravel being gently swished round in a tin can (for want of a better description).

A couple of gentle blips on the throttle clears it but it gave me heart failure the first time it did it :eek: .

I suspect this is just the 'diesel simulation' mentioned in other posts but as it's only recently started....

I get the impression from other posts that if this was the duff coil problem, it would have come on more suddenly and be drastic in effect?

Any ideas as to things I can easily check to narrow it down (or suggestions for making the problem more reproducible)?

Keep it fairly simple if you can - I can wield a spanner but lets just say every time I open the lid my first thought is 'surely that can't ALL do something constructive' .

Some questions that might help for now...

How would I identify what series coils I have fitted (and what series were the duff ones)?

How frequently should plugs/air filter/fuel filter be changed on the Octy RS?

Thanks all

Dave

check DV,

change oil but use engine flush first.

DV causers the stutter...

the gravelly sound would most likely be the tappets not getting oil... so oil may be shot and not circulating -best to flush and fil with new.

The problematic H version of the coil pack is on the left. This can be identified in situ if the top of the arrowed 'slot' is visible. The J and L versions do not have the 'slot' visible when fitted. The L version is the warranty replacement for the H version if fitted, regardless of whether the H has failed.

More pictures of what is involved in a changing the coil packs can be found in the Gallery here.

Thanks for the hints folks.

Boost stutter is definitely reproducible now so it's back to the dealer asap.

Far as I can tell, it looks like I do have the H series coils so that may be the source of the idle problem/fuel economy drop. As to the engine noise after standing - I'd expect the oil to be ok as it's changed regularly (with filter) and only done 2.5k on this lot. Still - if it's clogging up I guess new oil won't help. Maybe the oil the dealer's been using isn't the best. I'll see if I can get them to do a flush/re-change when it goes in to sort the rest.

Cheers

Dave