Hi gang,



New here to the forum, and hoping for some advice on my 2009 base convertible, automatic, with 118k miles.



While at throttle, the car is flawless; fun, powerful, etc. Just love it. At idle, or navigating at slow speeds in a parking lot, its a mess!



Chasing what I think is a vacuum or timing issue at idle, I have done the following:



1) new timing chain (by Mini dealer; 102k miles

2) new VANOS (both)

3) new OEM oil cap

4) new valve cover gaskets (complete)

5) changed oil every 3-4k; check at each fill up, and its never low (does not consume oil, either)

6) new PCV valve (kit, not the entire valve cover)



So, with cold or in closed-loop, it gently hunts for RPM between about 650-720; not violently, just slightly up and down, up and down. Coming to a stop at a light, it’ll drop out of gear, RMPs will plummet to about 625 or so, then pop back up to 700. Before I changed the VANOS, it would almost stall, getting to around 300 RPM. Using my OBDII reader on my phone, short term fuel trim, at idle, bounces between 0 and 0.8…oscilating. I can’t find any info online of what is a healthy number.



Idle in park seem steady, but really smooth. With the hood open, the engine is visibly vibrating.



I’m at a loss now. It ‘seems’ like a vacuum leak at idle, linked to PCV, as the car performs really well under throttle (BTW the VANOS were shot, as I saw a HUGE performance improvement after their replacement). I have a new PCV hose ready to install, thinking the original may be compromised, but I quickly found out the intake manifold needs removal to that job, and its way too cold out now for that! But if I go that route, I could change out all the gaskets in that system, as well as injectors….



So, what do you all think of this saga? I wanted to get more feedback before digging into the manifold…



thanks for any help you can provide!



Matt

 

Looks like a lot of work done already.
I take it that NO CHECK ENGINE lights are on?
Are the spark plugs new ? Bad plugs or coil packs should give you a light on condition.

Maybe put a vacuum gauge on it at idle and driving to get a good idea what's going on. That would give you info on timing, leaks, etc.
Check out the gas cap too? Properly vented?

My first guess, and totally a guess, was that the Vanos was defective and/or of the wrong viscosity oil.]
For the $$$ they cost, I would change it out and see. I've had bad ones before.

Good Luck,
Bill

 

thanks Bill! I appreciate the input. No CEL, all new plugs. One thing I read was about readapting the vanos after the replacement. I did not do this. Doesn’t the ecu readapt from driving?

I need to get a vac gauge! Can you suggest a brand? And where do connect? Oil cap?

yeah I’ve check the fuel cap as well.

a real mystery I intend to solve!

Matt