# Removing Oil Cap Causes Engine to run Rough



## rpdl62 (Aug 7, 2008)

When I remove the oil cap from my 2002 VW Passat 2.8L V6, while the engine is running, the engine "chugs" like it wants to stall. When I re-install the cap, the engine runs perfect once again. It seems to be sucking a lot of air with the cap removed. Is this normal??


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## shipo (Jan 3, 2006)

*Re: Removing Oil Cap Causes Engine to run Rough (rpdl62)*

Yes, completely normal. By removing the oil cap you are allowing air to enter the crank case, air that eventualy finds its way through the PCV system and into the intake manifold. Unfortunately that extra air hasn't been accounted for by the ECU, and so it throws the air/fuel ratio off, hence the rough operation.


_Modified by shipo at 11:33 AM 8-7-2008_


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## rpdl62 (Aug 7, 2008)

*Re: Removing Oil Cap Causes Engine to run Rough (shipo)*

Thank you so much for the speedy reply. Having just had the Timing Belt, Belt Damper, Thermostat, Water Pump, Gas Tank, etc. replaced, I guess I am a little overly-causous because out of warranty repairs can be very costly! Thank you for putting my mind at ease!!


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