Allright, here's my problem. While accelerating between 2500-3000 rpm in lower gears my engine stalls then puffs out a ball of smoke. This only happens occasionally (3-4 times a week) and doesn't seem to be affected by engine temperature. I was told by my SA that the problem was more than likely bad gas and that the engine lost ignition to save engine wear. I only use 93 octane super unleaded gas and have tried gas from several different stations even one place that sells non-ethanol laced gas. I have no CEL and car seems to run fine after it blows its smoke. My ride is an 07 MCS manual with 34,000 miles. Anyone else had this problem? How was it resolved?

 

Sounds like the rings are lining up...

 

1) Is there a specific point during the acceleration process that the engine stalls? In other words, does it happen the instant you push down on the pedal, or when you lift off the pedal to shift to the next gear, or ??

2) Is the smoke blue (which would indicate oil), or black (unburned fuel)?

 

Or white smoke (coolant in system)?

 

It is definitely unburned gas. The ignition is shutting down supposedly to save the engine from pre-detonation or backfiring. There are no CELs but the SA was able to find it saved in the computer. Seems to happen during mid acceleration.

 

It's detonation. I've had the same problem since January and the both dealers I've been to blame bad gas despite the problem persisting for nearly 6 months and my using only 91 octane gas (highest octane available here) and only using gas from top tier stations.

I would LOVE to hear if you come up with a solution, this problem is making me hate my mini!

 

Glad to hear that I'm not the only one. Its really starting to bother me also. I don't want to be put off until my warranty is over and discover that its a serious issue.

 

did he call it a 'super knock' ??

What mods if any do you have?

 

My motor is stock, not sure about grovedaddy's.

 

No, haven't heard "Super Knock". I had a K&N air filter but have removed it the last three months in an attempt to stop the problem. As I said earlier, I live in Texas where I can easily find 93 Octane. We are planning a road trip to Montana, Idaho, and Wyoming. Along the way a person is lucky to find 89 Octane available. Anyone know of a catalytic converter safe and BMW approved octane booster to keep in the car in case problem gets worse?

 

I'd pull and inspect the plugs to get a "picture of health" in each cylinder. I'd also try any recommended injector cleaner in your next fill-up ( you have direct injectors, yes? ).

My guess is you have some carbon buildup that, under the right circumstance, sets off the computer, it thinking there's pinging happening. The "event" loosens and blows a bit out until it builds to the next "event".

Granted, my theory is reaching for the fence, but fairly easy to test as suggested in the 1st. paragraph..

I'm curious about your miles per gallon.. is it lower than normal, indicating it might be running a bit rich?

Finally, are you driving it like my Grandma? I'm guessing your motoring strong like a good Mini owner should, but it needs to be asked in the process of covering at least some of the possibilities.. Sorry for any stubbed toes..

Bill in P.G.

 

Sound advice, except I'm still under factory maintenance. MINI should pull the plugs and investigate instead of handing me a line about "bad" gas. I'm getting 34-35 mpg and I am a spirited motorer. I was mainly curious as to how many other R56 owners had experienced this problem, if any.

 

G.D., I absolutely agree that you should not have to be the one under the hood, I too am interested in how prevalent this problem is, and I'm greatful you started the thread.

Suggesting to the service person at the dealer that they inspect the plugs might result in rolling eyes, despite the fact that it's the first thing us old time wrencher's do when dealing with missfire issues. I think their reliance on computer feedback for troubleshooting has them stuck in the box..

We check plugs, for the like reason that doctors still wear a stethoscope around their neck..

I went and got on my soapbox.. sorry..

Bill in P.G.

 

I'm averaging around 30 mpg and definitely not babying the car. It's a lean condition that would lead to detonation and I'm fairly convinced that this is the issue. If you look at dyno curves with an AFR graph for our cars, you can see that they run VERY lean up until around 3500 rpm and then start to level out. My guess is BMW programmed them that way for the good gas mileage we get, but it's very frustrating when problems like this start happening!

 

I will definitely demand further investigation at my next service. My OBC says that I'm due in 700 miles and with 34,000 miles on the car this will be probably be my last service under MINI maintenance package. I'll post again with any findings.

 

Problem solved. We got a new set of plugs with latest service and no more stuttering and smoking.

 

i absolutly have to same problem i will ask for them to look at it again, they know i have a history with them about the hesitation upon acceleration. but i think i am more concerned with the cold start issue, being a unsolvable problem for the future.

 

I just took my 07 MCS in for its 30,000 mile service. About two months ago it started hiccuping on freeway on ramps. I told MINI about it and they kept my car for a week. Wound up cleaning the valves. Said that it was carbon build up on the intake valves. With direct-inject fuel, the gas doesn't flow past the intake valves anymore and therefor doesn't clean them. At this time they know of no fix and can't guarantee that it won't happen again.

 

Hi Ya Chili,

What's your mileage been like?

Speaking of cleaning valves, I used to have to pull the head on my 67 MGB and "De-carbonize" the valves and squish bands every so often.. Worn S.U.'s didn't help matters.. You brought back old memories..

Bill in P.G.

 

Mileage has been great. I'm getting almost 37 mpg on my normal commute. Yesterday I took a 360 mile drive and averaged 40.4.

 

i have an 05 s with 57,000 and i drive hard, ive had this stutter for some time now and just had the car in for service and the plug were changed but didnt not fix the problem i am lost please help if you have found a fix. thinking about getting performance wires and a new coil from msd

 

the hiccup and puff is referred to by the DME and diagnosis softwear as a 'Superknock' There are several possibilitys on why your car is superknocking; poor quality fuel is a large contributor to the issue.

Also depending on how many miles are on it, there could be excessive carbon built up on the intake valves.
If your car keeps doing this in regular intervals; the CEL will come on.

hope this helps

 

Ok, I have an 09 Factory JCW with 8K miles on her. About 2K ago I started to get the "SuperKnock". Brought the car in for service and they said the same things others have heard. Bad gas, switch to Shell or Chevron or Exxon.

I switch to each of those and even get Octane boost (I came from Florida where I could get 93) and still each tank full gets me the same problem.

I am going to bring it in again next week and see if I can get them to swap out the plugs as an attempt to fix.

By the way, I have driven her like she wants....hard and fast!

 

ok.. so im not the only one that has this problem. Seems to me that it happens more in hot weather (less dense air).

It happened with a CAI and at stock. Freaked me out today because as i was accelerating hard in 3rd gear, i feel a stutter and then i see a puff of smoke (not black, not white) shoot out of the exhaust. No CEL though. My MINI is due for service so ill have them check that out as well. Sounds like plugs fixes the problem?

 

I've noticed the same power "Hiccup" a couple of months ago and noticed it big time when I was at the Dragon this year. However, I JUST had my plugs replaced in Feb. and it didn't fix it for me. Also, I had to have my mini towed from the Dragon to Century Mini In SC b/c of what I thought was a timing chain tensioner about to snap but it turned out that my dealer didn't fill the oil back up in my engine after my oil change in Feb and was running with a 1/2 a quart or so far that is the reason. (She is still in service in SC and will get another update tomorrow) You can see the full story here: http://www.sunshineminis.org/forums/...ic.php?t=20206