Cylinder liner wear.

[12th]

Right. Car's at MRC for investigation, symptoms being an uneven power delivery at low revs when cold, quickly goes away when warmed - though I don't think it ever feels quite as smooth as when in rude health. Feels very strong though, I don't think it's down on power (we'll see about that though...). Starts fine, no smoke or hesitancy, so it doesn't feel like anything major.

But: compression testing done elsewhere suggested seven of the eight were low, could be a multitude of things which is what perturbs me.

So, if it were cylinder wear, what symptoms would I expect? I also gather that cars so affected with cylinder liner wear tend to become undriveable pretty quickly, which I am clinging to as I obviously don't want a bill of wince-inducing proportions. It's been like this for two to three months and if anything is not as bad as it had been.

I know I'll have an idea sooner rather than later (I hope!), but if there is anyone able to offer reassurance I'd be a happy man. Walnut cleaned last July, but having a carbon clean as well as diagnostic.

Where's the 'fingers crossed' emoji?!

[12th]

Oh, oil consumption not changed, and always used V-Power.

[rs user]

needs a compression check again -rs4 motor not prone to bore wear unless carbon cleaned carelessly and lumps down bore-unlikely to be them all in any case
even if compression is low could be top end/head problem...the way to find that is a leak down or the old fashioned way of a spoonful of oil down bore-if it increases by lots its a bottom end problem

[12th]

OK. MRC have had it on the dyno - showing just under 410 bhp - although as it has a DMS remap that's still a little down on what I'd hoped for.

- Coil packs are old.
- Spark plugs were replaced by Audi last Oct but are single electrode rather than the triples recommended.
- PCV valve is original, replacement suggested.
- Flaps in manifold are not exactly as they should be, so removing is recommended along with their stage 2 mapping.

The DMS map was not personalised to the car, as they got confused and assumed I was travelling to Southampton, not Birmingham as arranged - so I'd hope that a fully-tailored map will be better (by which I mean more powerful, I'm afraid!)

Just waiting for a price to authorise the work, and mercifully they see nothing that would suggest a major issue. It is running a little rich at idle, which may be washing oil from the cylinders at startup, and hence the compression test results.

I want my car back, and everything back to 'normal' - I hate not having it around!

[MIDZ]

Na, I very much doubt the accuracy of your compression readings. Obvious symptoms would be blue smoke when cold and excessive breather pressure when running as the compression gases leak past rings and head to the sump. Might be able to verify this by removing filler cap when idling

[12th]

Thanks for that. Having a quick carbon clean too (it's not bad), so now I'm playing guess the bill? £3k?

[12th]

Replaced high flow filter as well, total just over £2,300. Or a fraction of depreciation if I'd changed cars, I think. Dyno at 434 and 485 nm, which I am happy with.

Thanks to all for the tips (this thread and elsewhere), recommendation of MRC etc etc.