Hey everyone, I had a brief yet strange behavior today. Stock 2011 MCS automatic with 1100 miles. I was going about 70 mph on the highway just cruising, and I dipped into the throttle VERY lightly (I'm talking maybe 10% -- not enough to even get into boost) and the car did a really weird hesitation/stumble which was accompanied by 2 distinct "ticks" that were easily audible. The ticks seemed to come from down pretty low, maybe transmission area. I can't imagine it was engine pinging as I wasn't even on the gas much at all. Has anyone ever had this happen? The car seemed fine after that, I could not reproduce...

 

May have been just a random and passing fuel feed hiccup, but given the history of the HPFP on these cars, I wouldn't rule out the possibility that yours is exhibiting the early signs giving out...

 

That would be pretty sad with 1100 miles and 4 weeks of ownership. Hopefully it was a one time thing. Ive had about 25 new cars in my life and this is the only one to ever exhibit strange behavior so quickly. I hope I dont regret buying this thing eventually...

 

Agreed. But the mileage is too low to be something like carbon build-up, which is why I leaned toward the other things (random hiccup or HPFP).

But stranger things have happened -- to cars built by every manufacturer. You're under warranty for a good long time, so if the HPFP does give out, you should be covered.

 

My 07s has had the same hesitation and noise constantly. Back to the dealer 6 times. they can't find a thing and look to humor me.

 

Ok this happened again today, but I have more information this time. This happened both times after me driving down from my home at 7700' of elevation, down to the west side of the Denver metro area which is probably 2000' lower. Both times it was while giving some throttle just shortly after exiting the mountain pass. The drive from up where I live down to Denver is downhill for miles, so doesn't really put a load on the car -- its mostly engine braking etc.

This also started happening right after I filled up with Shell gas on Thursday night, which I've not used in the MINI before. I am now suspecting that the change in altitude combined with some questionable Shell gas might be the culprit. Today the problem happened twice in quick succession right after exiting the mountain pass, then was again just fine a few minutes later driving around Denver, even at WOT. The 2 ticks I heard each time was possibly detonation followed instantly by the bog/power cut-out which would be expected behavior if the engine was cutting timing to prevent the detonation.

I will keep an eye on it and update this thread either way over the next few days to a week. I'm going to fill up with Conoco that I had been using next time, and then take the same route down to Denver to see if I can recreate the situation. I am at 1/2 tank, so it'll take me a few days to get that down. The car seems totally fine either way up here at home, or way down in Denver, its just the 2-3 minutes after going down to Denver that this has happened now...

I have had turbo cars in the past that simply didn't like certain brands of gas, and I'm wondering if this MINI just doesn't like the Shell stuff, and isn't compensating for the elevation change very quickly on it.

 

That's certainly plausible. Like Sherlock Holmes advocates: eliminate all things that are not the problem, and whatever remains is likely the culprit...

Switching gasoline brands would be a good way to narrow down the cause. It may also just be that particular Shell station got a bad load of gas, or moisture in their tanks. I've personally never had a problem with Shell in other vehicles I've owned, but must admit that I have yet to run Shell through my MINI. But I'm also at a considerably lower altitude than you, as well...

Another possibility to consider is that whatever is controlling the air-fuel mixture may be experiencing some minor "confusion" with the rapid change in altitude. Perhaps a sensor is flaky, or some valve is sticking?

One other possible explanation is, for lack of a better term, icing in the inlet manifold (known more commonly in the past as "carburetor icing." I realize these engines are injected (no carburetor), and it's very rare for them to experience this type of problem. But it's still possible for icing to develop in any internal combustion engine under low throttle settings with favorable atmospheric conditions (NOTE: this chart is mainly applicable to aviation, but still illustrates under what conditions of engine power temperature/dew point that icing in the inlet manifold could occur). And I seem to remember reading some threads when I first joined the forum about some of the inlet manifolds developing ice in them simply by being parked overnight in the right kinds of conditions (generally quite cold and damp), and thus being difficult to start in the morning.

 

Yes all possibilities I guess. Since it started happening RIGHT AFTER I filled up with Shell, the gas is the most obvious thing to rule out. I've not had a problem with Shell in the past either, but there are so many variables that could come into play to end up with either less than 91 octane in their tank, or as you said moisture or whatever, that its hard to say. I had a WRX years ago that just hated Chevron gas, which is considered a "top tier" station, etc. It didn't matter which one I went to either, it just always pinged and bogged on Chevron, so I never used it. I'll go back to the same Conoco I filled-up with before the Shell, then take the same route down to Denver and try to recreate the issue.

At first I wasn't convinced it was pinging because of the location of the sound, but its plausible I guess that it was just echoing through the exhaust or something, and thats why I was hearing it lower than I would have expected in the engine bay...

If it happens with Conoco too, I'd have to agree with the car just not being very good at compensating that quickly then. As I said, I can't recreate the issue more than 3 minutes outside of the canyon once I'm down in Denver, and its fine after that. I'm hoping its just a combination of questionable gas and the compensation for altitude thats making a perfect storm...

 

Just to follow-up on this, I have had a tank of Conoco premium in the tank for about 250 miles and the behavior is gone. Therefore, this appears to have been "bad gas" from Shell, and knock/detonation and timing being pulled.

 

Shell gas is definitely your culprit. It's the nitrogen they add to the gas. Makes the MINIS ping a lot. Sunoco FTW!!

 

Man, all these fuel threads are confusing. Isn't shell supposed to be top tier gas and considered one of the best?

 

It is, BUT, how the individual stations maintain their tanks has something to do with the issue. Also, do you fill up you Mini when there is a fuel delivery tanker in the station or immediately after one has been there?

I usually use Chevron but on occasion use Shell. I have political reasons to not use Shell; they were supplying North Vietnam with fuel during that war and being a Vietnam Vet this irks me.

S.

 

Don't mean to hijack the thread but, I didn't know Shell was selling the north fuel.

 

I did get mine to ping the other day on Conoco as well. Its not as prevalent though, as its only happened that once. I was near my home which is at 7700' of elevation, and traveling up hill and giving it just a slight amount of gas in a high gear under load basically. Really at this elevation, 91 octane should be plenty for this car, but its finicky I guess.

Shell is on the "top tier" list, but I won't use it again in this car. I had a fairly heavily modded WRX years ago when I lived in Salt Lake City that hated Chevron. It didn't matter which station I used either, and I'm not sure why. Again, a "top tier" fuel. I always fill up my Xterra (and before the MINI, my Mustang GT) at the local grocery store's Loaf N' Jug which is nothing special but a newer station. I'm getting tempted to put that into the MINI next time for grins. It doesn't have the level of detergents/additives as the "top tier" fuels I'm sure, but I'm curious if the octane rating is more "true". If the car won't ping on that, I'll use it mostly and run a tank of one of the other "top tier" brands thru it once a month or something.

 

Exactly as you describe! Using Quik Trip station in Az. Will fill up next time with Chevron and report back. 2008 MCS.

 

Had the MINI in today to replace a faulty thermostat and temp sensor (at a tender 2900~ miles) and complained of the superknock. Tech blamed the faulty temp sensor claiming that it was used to calculate timing. Its a reasonable thought, but I'm betting he's wrong and it'll still happen anyway. Dealer advised to keep an eye on it and let them know how it goes.

Since I started adding a bit of Torco Accelerator to each tank, the superknock has only happened twice and very infrequently as compared to the frequency previously. Will report back my experience either way, but only more time/miles will tell.

 

Pinged and stuttered a bit ago while going up I-70 from Denver to where I live. So, that answers that.

 

I had this happen as well. Mini eventually pulled the spark plugs and said that one of the plugs was dented/damaged. So they switched all the plugs. Problem never came back.

HOWEVER, ever since they changed the plugs, now I have an erratic idle problem that they can't resolve. It's been over a year I believe

 

Did MINI tell you what number plug "Was dented/damaged"??? I would use a scope and look into that cylinder to look for damaged piston and or valves. Unless they put in a damaged plug from the factory, or wherever the last plugs were installed, something else is going on.

S.

 

Yeah I thought about looking into some possibly better plugs (not sure what the specs are), then the other side of my brain said ITS A NEW CAR!!!! so I gave up on that thought. Right about now, I'm just hoping the thing doesn't completely explode for about 15k more miles, and I'll get rid of it. Its the first and last MINI/BMW for me, this is all ridiculous...

 

(sorry to hi-jack)

They thoroughly went over my car and found absolutely NOTHING wrong, even though it has an erratic idle at time and throws check engine lights. I still wonder if these two issues are not somehow related.

 

That figures. I called MINI about the superknock when it first happened, and since there was no check engine light, the service clerk told me they likely wouldn't do anything about it. I didn't bother to waste my time going there for it. This last visit was for a defunct thermostat, so I mentioned the superknock just to have it logged "officially", and they blamed the thermostat for it. Of course, the superknock happened the very next day so as I expected, was unrelated.

I had been planning to take this car on a 2000 mile roadtrip later this summer, but if I end up going, I think I'll rent a car. Its sad to not trust a brand new car with 3000 miles on it to be reliable enough to take a 2000 road trip.

 

I've heard that my fair share of times. Absolute rubbish

 

Yeah its funny to me that a car can throw CELs and the dealer still reports back that "nothing" is wrong with it. That just tells me either the thing isn't engineered well at all, and/or the techs have little understanding or resources pertaining to how it actually works...

 

Your second guess would seem to be correct - little actual knowledge on the cars workings. Mine has super knocked for two years and every time I bring it up its some different reason. It's almost laughable to hear the SA grab at the latest all encompassing explanation.