Engine MINI R56 Cooper Crankcase vacuum test, No vacuum a bad thing?

Discussion in 'General Technical Questions and Answers' started by Ron Day, Mar 3, 2019.

  1. Ron Day

    Ron Day New Member

    Feb 19, 2019
    Milford, PA
    +4 / 0 / -0
    I was going to make this video myself, but since it is already made ...

    My car threw a 2187 ( lean air mixture ) error after a local garage removed and replaced the valve cover as part of a timing chain tensioner replacement. The car threw the error the morning after the repair and had a very rough idle, especially when cold. After my local mechanic did a smoke test and checked the vacuum lines he suggested that the issue might be the PCV valve in the cover. He verified this by doing the above linked test which showed no crankcase vacuum at idle. Not wanting to replace the cover I ordered the PCV valve replacement from ECS. The morning I went out to replace the PCV valve in the cover the rough idle at cold start was not there, but the code was there and I could not delete it with my Scan Gauge, so I warmed up the car, checked the vacuum (none), and proceeded to replace the PCV in the cover. When I opened the PCV cover the original PCV plastic looked brand new, but I replaced it, put the new cover back on and when everything was put back together..... still no vacuum. I bought a mini specific comm (I put a link up to that here on the forum $49 on amazon) which was able to clear the code and after driving a total of about 400 miles, the code did not come back, despite no vacuum in the crankcase.

    A fellow board member put the car on his very impressive computer and did not pull any codes.

    In the 400 miles the car only struggled at idle once or twice. It does Idle around 870 RPM and throws, a "little" more white smoke than it should for a fully warmed up car ( not a lot, but noticeably more than other cars I'm idling nearby.

    Another thing that I don't get, If there is no vacuum, then why does the idle change so much when I remove the cap? Isn't no vacuum, no vacuum?
    Good advice is usually, if it ain't broke don't fix it, but this is buggin' me.

    This is an R56, N12 (non turbo) 2009 Justa Mini with 56K miles

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