[mike1967]

that to me points at burning oil ie piston rings or valve stem seals or even crankcase breather throwing to much vapour in to inlet manifold ,, chai of events i would guess to be this the oil burns and increase the HC readings this also contaminates the 02 sensor and cat,, pull the upstearm sensor out if white in colour then its oil burning and do like i say.. i just rebuilt a n14 engine with the latest piston ring set ho wish i never did as allowed oil past the rings would smoke on idle wispy smoke and would also smoke badly on the over run at bottom of a hill then hit throttle. i stuck that on gas machine and CO was through the roof and so was HC HC is more to do with oil burning but oil burning will also increase CO levels as its a oil and fuel is a oil as such,,
ways around do oil change use a 5/40w fully syn oil might be worth trying stuff called stop leak it swells the oil stem seals if it those, if your mini is a n14 then fit catch cans on breather system might help get through mot,, i'm in middle of rebuilding this one again with 3 piece steel piston rings unlike the last set that were coated single piece ones and were all kinds of crap

 

[mike1967]

not burning any oil then 02 sensors and cat or injector maybe r56 has prince engine in it these are prone to timing chain stretch as well this can also effect the reading increases overlap between inlet and exhaust valves dumps unburnt fuel on upstream 02 sensor and cat,, normally around 60-80k such cars have new cat and 02 sensors as most people treat the symptom and not the causes as well then 10k later do it all over again, if not had a chain done in past 60k them it will need one for sure they all do not a if its a where, also need to check the coolant sensor with live data see that it starts at right temps ie if 20c it start within a few degrees of 20c and tops out at 112c..

 

[mike1967]

So, after various diagnostics and live readings - it appears that there is a distinct lack of output pressure (mechanic says it should be something like 20, but it's only giving out 5) ..

They've seen it before on this engine, and they think it's the timing chain / and possibly the sprocket jumping due to missing teeth ..

So cheers mike1967 ?

its very common bud its what they do like said i live by change the timing chain on the prince engines at 60.000 miles on car that are maintained well and driven lightly,, on cars that have had hard life 40-50k have seen them fail before, also been seeing valve seats dropping out on some that get so hot from retarded running and cracked valves as well, its not a really hard job to do its just all about the process as all sprockets free wheel while setting timing and rely on stretch bolts to hold them in place as such, no timing marks all done with lock tools

 

[mike1967]

Update - had the timing chain and VVT stuff replaced, and the Mini passed with flying colours. No advisories or anything.

Cheers all ..

most are that to be honest, ie 60.000 miles ish on a chain is its limit