OK, I need a little reassurance here, I noticed when I am in 6th gear at around 50 MPH, when I simply floor the gas pedal and let the speed increase through 70 MPH I will get a puff of smoke. (Oil) This is the ONLY time it will do this. Running through the gears normally, hard accel etc, no smoke. I am thinking I'm creating the "perfect storm" in regards to the oil usage issue. Moderate speed and WOT = greatest amount of intake vaccum that is drawing oil out of the top end valve area. Any thoughts on this. Could someone try this with there cooper S and let me know if you get the same result?

2008 Cooper S No Mods...

Thanks,

John

 

Wide-open throttle at moderate load causes a low-vacuum condition, not a high-vacuum one. You'd actually see a much higher vacuum at the intake manifold when you come off the throttle at the end of the acceleration, rather than when you're actually still accelerating.

Do you feel any kind of a "hiccup" or hesitation at the instant the puff of smoke appears? How is your oil level - possibly a little bit high? Do you have a Cooper or an 'S'? Lastly, what grade/brand of gasoline are you using?

 

Thanks for the correction on the vaccum, Oil level is spot on. ( I had just changed the oil the day prior and I thought I had over filled it.) No hesitation when it occurs. Using 91 grade gas from Diamond Shamrock. Cooper S no mods. Now that I think about it could this be an overly rich condition?

John

 

The only other MINI cases I've heard about involving a puff of smoke *during* acceleration have been when the increased load causes momentary pinging/detonation. the car's computer abruptly changes the ignition timing in order to compensate, and you end up with a small puff of smoke from incompletely-burned fuel.

I don't think you have a constantly-rich fuel condition, or you'd be throwing OBD codes from the oxygen sensors.

What's the altitude in Westminster? I know that 91 AKI is often the highest octane you can get, because the octane requirement for most engines decreases with increasing altitude. Unfortunately, this isn't the case for forced-induction engines (superchargers and turbochargers) - they still need the higher octane, even at altitude. My wife had a hard time getting over Monarch Pass in Colorado two weeks ago because the local 91 octane gas wasn't cutting it at 9,000 feet.

Maybe try a different brand of gas with some heavy-duty octane booster and see if you can reproduce the results?

 

Altitude here in Westminster is around 5500 feet. I will give the octane booster a try. I'm assuming I would not hear the pre-ignition? I would guess the computer would correct this condition long before you could hear it. I have driven all over the Rockies at altitudes up to 10K. with no drivability issues. It's not like I do top gear roll ons all the time, I just happened to notice the "puff" and now it's going to drive me crazy knowing it's doing it.

John

 

It's possible that the supercharger in my wife's MINI fares worse at high altitudes than the turbocharger in your car, or perhaps she got a bad tank of gas right before going up Monarch.

The computer will adjust the timing before you hear any knocking, but there is a condition in the MINI called "superknock", where under certain circumstances, the computer won't be able to retard the timing enough to prevent pinging/detonation. But I don't think that's the case here, because superknock is usually audible and accompanied by a stutter or hesitation.

 

Thanks for the info, I have a service appointment next week to get the windows reprogrammed and my hood scoop replaced. I will have a talk with the service rep then.

John

 

Good luck. Have the rep pull the codes from the ECU to see if you have the "superknock" code stored. A regular OBD reader won't display it, but the dealer's equipment will.