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Discussion Starter #1
I replaced my PCV on my N12 engine several months ago with one from Ebay, the Chinese version which comes with the clipped cap, diaphragm and new spring. At the same time I also replaced both Vanos solenoids, lambda senor and other new parts. Since then rough idle and stutter in 3rd gear until engine warm.
Taken me until now to sort the rough idle out. Ended up taking the PCV out and compared the new and old springs, the original is much thinner and less resistant than the replacement, keeps the valve/diaphragm open much longer. Put the old spring in and went for a spin this morning - no rough idle and no hesitation.
There were no codes (not expected) and no obvious excess oil consumption. Am hoping a couple of thousand miles has not damaged my cat running it polluted.
Anyway, hope this helps someone else who may have fitted the replacement PCV from Ebay.
 

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i've found a seller on ebay who sells complete rocker covers had about 5 so far and all have worked a treat but still £50 a pop but do get new gaskets so not to bad when compared to genuine £280 plus vat,, its removing the plastic clips on the old ones without snapping them off as old plastic gets hard and brittle,,,
 

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Discussion Starter #3
with all due respect Mike I was referring to the cheap Chinese N12 and poss other variant replacement combos. Yes the clips break, hence the need for the small PCV
\cover replacement but the spring is wrong. Too large and strong, not as yielding as the original and there lies the problem, open too long for the ECU to manage so when cold start throttle cuts it is still not doing it's thing and you get PCV problems with inlet and PCV not doing the correct thing. Replacing a complete cover on an N12 would be false economy.
 

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not knocking your cheaper way forward just putting the extra info out there what the other ways are and costs etc, i've repaired them a few times in past some work well some the thinner rubber parts have split after a year or so, they only do kits for n12 n14 with the plastic cap
 

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Discussion Starter #5
well, back to square one. I cannot find how to change the title but this has not been resolved. Idle still bouncing from 500 - 800rpm. No codes using Autocom. Am not one for replacing parts for no reason so am on hold. It does not cut out completely. If I blip the throttle I can create the condition but once warm it runs perfectly, full power, no misfires, nada. AM not about to invest in a new throttle body or fuel pump until something actually reveals itself as the the culprit. This all started around the time of new vanos solenoids but not precise on that either. My bad for the title
 

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mine done that right after i rebuilt it and gave a merry dance talking myself in to other things, lucky i have spare good 02 sensors and map sensors and throttle body and timing chain stuff etc tried it all first then bit the bullet got pump refurb £139 guy on ebay now car is back ful power never miss a beat and doing good mpg as well to be honest for what it is.. moine would when cold not idle right bounce around then next day would run perfect then next day bounce around again, then towards the end would not start for a good 20 times it fire up shut off and repeat 20 times or more then other days would be ok ish never knew from day to day what it would do.. until i got P2880 code think it was and loads of misfires,,
one thing you can do is this rule in or out inlet related or pcv , pull the pipe off rear of rocker cover and blank it off at the other end ie where goes in inlet manifold if car runs fine then know its pcv related if still same then back to the drawing board,, my mate works at mini as tech he's on the ball he was saying they see endless fails on these pumps and some random differences when they do,, and n14 and n18 pumps have a under 70.000 miles life span..
live data the fuel system with autocom look at fuel rail prescribed and actual reading if are not the same then fuel issue, also read injector corrections see of any stand out ie big difference from zero,, ie they should all flick from 0.30- to 0.30+ i have had them reading 3.0 before on 1 cylinder say and that was due to piston rings and oil burning or injector faulty and nozzle drip as the injectors are like a diesel share a rail pressure if get one leaking of pressure effects all the others and will bleed off cranking pressure on start up and put air in system as well all this will cause misfires
 
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