i am sur this is old hat to to the forum.

05 mini cooper. 44k miles. no mods.

for several months it has had a rough idle and would almost stall when RPM would drop during an idle especially if the AC kicked in. could never reproduce at dealership and no codes.

about a month ago it started to lose power with reving RPMs. then it became dramatatic and oil reads low. i was due for oil change so brought it in rather than topping off. i got a call telling me it was 4 qts low and the air filter was filthy and had two leaking gaskets. the gaskets were their explanation for the low oil. $877 later the filter, oil and gaskets were taken care of.

when i picked up the car it had even less power. maybe 20%. gas milage was maybe 15 MPG and rpms would soar with no power from 1k RPM to 4k. i got on forum and seeing the recommendation to replace the PCV valve i ordered one. replaced and noticed a dramatic improvement in power enough to feel it catch and accelerate, but still only feel like i have 70%—can't spin the tires or accelerated quickly. when i pulled the old PCV it was full of oil, but rattled. is this normal or should that line be dry?

the RPMs still jump occasionally between 2k and 4k with no power or throttle change. no codes at dealership.

theory:

failing PCV caused loss of power, burned oil, dirtied air filter and forced oil out through gaskets. addinl oil dropped power more as more oil was getting pulled into the engine? the new PCV is doing better for power, but maybe there is residual crap that needs cleaning. so i put in fuel injector, carb, etc. cleaner this morning. no improvement yet, but it has only been driven 2 miles since addition.

advice?

• should i Seafoam?
• is this all a sign of something that needs to be fixed that is obvious enough to diagnose on forum?
• should i raise a stick at the dealership about the replacement of the gaskets a symptom, not a cause of my problem? (from what i have read a bad PCV forces oil out of the gaskets making them leak even when they are not bad.)

as you can tell i know little of auto mechanics. speak in lay terms and help me educate myself to either fix it of be competent when it goes into the mechanic again.

thanks!

 

did a seafoam. seems to have more power, but still sluggish. still have 3/4 tank of gas with cleaners.

do i just wait?

 

A failure of the PCV system means you may have had some carbon buildup in the engine. This is the problem that is currently going on with '07-'10 MCS (you can read more here: https://www.northamericanmotoring.co...cv-system.html). Besides using Seafoam, you can also use fuel injector cleaner. STP has a four-grade scale. The 3rd level is a black bottle titled "STP Fuel Injector cleaner." Try one or two of these (one per tank). After that, use one "STP Fuel Treatment" every 3,000 miles or so (that's what I do).

Pull each spark plug and look at them to see if there is a buildup of deposits on them. Change them out as needed. Some MCS' come with NGK BKR5 plugs. This depended on where they were shipped to in the U.S. You can upgrade to NGK BKR6 plugs with no problem (that's what the stock plug is supposed to be).

You may also be dealing with corroded coil terminals. Pull each plug wire and inspect them. #3 is notorious for being corroded/rusted. They can easily be cleaned up with STP Carb Spray cleaner and a rag or a brass brush. Here is what mine looked like before I cleaned it up last year:



If this does not solve the problem, a trip to the mechanic/dealership may be in order.