Not to be the naysayer, but hasn't every software revision been intended to fix the stumble?

 

I think this must be the longest thread in Perf Mods since Magnaflow was claiming 18.1 HP for their MCS exhaust !! Sorry, nothing to really add to this thread until I get different software...

 

Ok one more variable to the list... I read pretty much every post in this topic, it seems like the stumble is severe in some not so bad in others. I have a March 25 build date. I just crossed over the break-in period and I admit - I drove it like a granny most of the time: launches were in the 1000 - 1500 range, and no full thottle. So fo me the stumble never raises its head at launch.

However, once I'm going up through the power ban at mid-throttle I get a slight stumble between 2700 and 3500 RPM. In my case "stumble" is an exaggeration: the engines power delivery is just not a smooth - its rough. Does this sound like the same thing? Maybe I never get the stumble at launch becasue I've been babying it?

It reminds me of my old volvo p1800 when the SU carbs were running way too rich. I know that's a goofy comparision but it really feels like its running overly rich at that rpm range (at least in my car). Who knows, look at the bright side: we all love our cars - if they get this fixed, they'll be even better!

 

>>However, once I'm going up through the power ban at mid-throttle I get a slight stumble between 2700 and 3500 RPM. In my case "stumble" is an exaggeration: the engines power delivery is just not a smooth - its rough.

this is what i think people have been calling the yo-yo effect. and this is my problem too. this is extremely irratiting. cause most of the time i'm mildly accelerating, and all i get is whoogawhoogawhoooga.

i'd like to know, is this the same thing as the stumble problem, or is this a bad throttle body or something? did anyone go to there deal with the yo-yo problem alone? cheers.

 

>>
>>this is what i think people have been calling the yo-yo effect. and this is my problem too. this is extremely irratiting. cause most of the time i'm mildly accelerating, and all i get is whoogawhoogawhoooga.
>>
>>i'd like to know, is this the same thing as the stumble problem, or is this a bad throttle body or something? did anyone go to there deal with the yo-yo problem alone? cheers.
>>
i've got the same thing with my 02 s. i took it into the dealer to get the cold start issue taken care of and told them about it. figured since they haveit for the day, why not look at that too. when i went to pick up the car they said they had no idea what i was talking about and tht they didn't experiance it during the test drive. so i guess i'm looking for the solution as well. i'm hoping that an upgraded chip will fix it. but i'm waiting on the guy to finish up his development on it still.

 

That's yo-yo. The stumble occurs at the exact instant you fully release the clutch in first gear. It only occurs in first gear, and it makes little or no difference if the gas is floored or just barely touched. There's no combination of gas/clutch work that will prevent it other than simply avoiding full clutch engagement in first gear.

 

well, actually mine only happens in second gear. never in first or any others, but oly second.

 

The stumble and yo-yo are two different issues. They may be related, but they are two distinct issues. The stumble is a momentary loss of power when launching the car from a dead stop in 1st gear. The yo-yo is a surging/wave-like throttle response that most often occurs in the 3000RPM range under moderate to fast acceleration. My car typically produces 3 waves or yo-yo's before smoothing out, again.

See ya,
JS

 

>>cause most of the time i'm mildly accelerating, and all i
>>get is whoogawhoogawhoooga.

A whoo whoo like this?

Jeff

 

>> The stumble occurs at the exact instant you fully release the clutch in first gear.

My dealer said it was becuase I didn't know how to drive a stick. I wonder if that is the company (BMW) mandated comeback to a owner complaining of the stumble...

 

"The stumble occurs at the exact instant you fully release the clutch in first gear. It only occurs in first gear, and it makes little or no difference if the gas is floored or just barely touched. There's no combination of gas/clutch work that will prevent it other than simply avoiding full clutch engagement in first gear. "

Actually some of us can feel it in higher gears too, just to a lesser degree. In my case I can feel the stumble in 2nd and 3rd gears but it's not nearly as severe (doesn't make the nose of the car dive), maybe because I'm already moving and that keeps whatever sensor that screws up 1st gear starts from screwing up the later upshifts as much.

I also get it whether DSC is enabled or not, and whether I'm turning or going straight. The only thing I haven't tried is "fully" engaging the car in reverse first to see if that makes it go away, because I don't have enough room in my cul-de-sac or anywhere else I drive to drive in reverse for that long. Someone on mini2.com said that worked for him.

I was going to take the car on a 1000-mile trip to Florida tomorrow but today my "service Engine Soon" light came on again for the 2nd time in 3 weeks. I had also noticed that while driving in the heavy rain we had here in Atlanta this week that my "Check Filler Door" light came on a few times. It went off after the rain ended though. So I guess I'll be leaving the POS (er, car) at the dealer while I'm out of town.

Wonder what I'll do if they have to buy it back due to the lemon law?

 

>>"The stumble occurs at the exact instant you fully release the clutch in first gear. It only occurs in first gear, and it makes little or no difference if the gas is floored or just barely touched. There's no combination of gas/clutch work that will prevent it other than simply avoiding full clutch engagement in first gear. "
>>
>>Actually some of us can feel it in higher gears too, just to a lesser degree. In my case I can feel the stumble in 2nd and 3rd gears but it's not nearly as severe (doesn't make the nose of the car dive), maybe because I'm already moving and that keeps whatever sensor that screws up 1st gear starts from screwing up the later upshifts as much.
>>

The reason why you feel the stumble more in the first gear is because the engine has a much larger mechanical advantage in the 1st gear. This is similar to getting much better engine braking in the lower gears compared to 6th gear.


I had my Cooper S for a few days now and I also have a stumble in 2nd gear around 2500 rpms but only happens when the car is cold (as in just leaving my driveway). I did not run into it when it is hot. The car is a 5/2002 build that I picked up used this week. Chili Red 2002 with NO options other than R90 wheels and roof rack.

Bora

 

Unfortunately I get the stumble even when the engine's warm, although it is worse when cold. Mine was delivered last September so was built last summer I guess. I just bought it used about 3 weeks ago. And this will be its 3rd trip to the dealer in 3 weeks.

 

I have a Cooper and also experience this stumble. I talked with the Service Manager last Thursday and was talked out of getting the 33.2 software fix. She said there may be yet another patch coming soon. She also said some people got some relief from this last winter by using a lower octane gas, with less alchohol.

Sunday I talked with the mechanic at the gas station near my house. He said the fuel has 7% alcohol during the winter as mandated by law; however, the gas companies get a tax break for continuing to use alcohol the rest of the year. Now they use EVEN MORE alcohol (up to 10%) during the summer, at least in the fuel delivered to large cities. He said he gets 3 mpg better mileage by buying his fuel outside Portland. He also said the Lexus dealership across the street was coming in and buying fuel a while back to experiment with reprogramming the ECU because their customers were complaining about the same issue. Lexus Corp. finally came up with a software solution while they were experimenting.

Apparently we are not the only owners of a car marque experiencing driveability issues related to the government-mandated crap gas we are getting. Why is it that government lawmakers only obey one law, the Law of Unintended Consequences?


_________________

 

Software problem? I've been following this thread for awhile now and I have a 2003 MCS that has this "Stumble" problem. It seems to be the worst when the engine is cold and gets better when warmed up but still occurs. I live in Florida so "Cold" isn't very cold, it's probably worse for others in colder climates. Everyone keeps talking about this being a software problem in the ECU. I'm having a hard time understanding this. I have had carburated cars that had stuble because of poor carb adjustments and this isn't that type of problem. When the stumble occurs in my car it's alway's at the release of the clutch in first gear. It happens right when the clutch grabs the flywheel. The engine never feels like it's stumbling because of a fuel problem. The clutch just doesn't like to slip nicely into place it just goes from slipping to grabbing with the last 1/16 of pedal travel. I don't see how this is a software problem, unless the problem is going to add more torque and low end power to the engine allowing the clutch to slip better. I don't hear anyone talking about this being a Mechanical problem, why? I don't see how any software upgrade is going to fix this issue at least not 100%. The engine in the cooper is very small - 1.6L it has very little torque and very low compression because of the SuperCharger. This compouds itself at low RPM when the engine gets loaded during first gear acceleration. It seems to me that this could be resolved better by going in the direction of using a different clutch/clutch spring combination. I think that's why this problem is not fixed. If it was a software problem they would have a fix for it. There is no mystery to fuel and spark curve programming in the ECU. That should be a simple fix at almost no cost for MINI. So why isn't it fixed? Probably because what will fix it will cost too much for MINI - replace the clutch in every MCS? I don't think so.

I know alot of people who drive cars may not be mechanically knowledgable about how they work and that's understandable because you would probably have to be a mechanic or someone with extensive mechanical background to figure out what this problem is. I just feel this is a big snow job on MINI's part to play dumb with the general public. "It's a software issue and were trying to fix it", "You just don't know how to drive a stick shift". I am a mechanic (aircraft) and I've built several cars, engines and I'm currently building a Cobra kit car. I just got done attaching the transmission and clutch. It's also fuel injected and I'm installing/Programming an ECU I built myself so I am knowlegable about how cars work. It just doesn't make sense to me that this is a software problem. If it was, it should be happening a specific RPM and not just when the clutch is released. It should also be happening in any gear at that RPM. Mine doesn't, it happens only when the clutch is released and at whatever RPM I deceide to release it at. The lower the RPM the better it does because the difference between the speed of the Engine and the speed of the clutch are closer to the same speed. The more you rev the engine and release the clutch the more noticeable the problem is and it seems to get better when the clutch is warmed up - because a warm clutch slips better.

 

I'm no mechanic, but initially I thought it was clutch issue too, but the more I hear about owners who started having the problem after going to dealer for software upgrade then I changed my mind into thinking it's the software. I think you also make good sence too. Again, not being a mechanic or close as such I can't even start to side one way or another. Maybe someone who had the stumble but upgraded to a higher performance clutch system may be able to shed some light .


Peter

 

>>I'm no mechanic, but initially I thought it was clutch issue too, but the more I hear about owners who started having the problem after going to dealer for software upgrade then I changed my mind into thinking it's the software. I think you also make good sence too. Again, not being a mechanic or close as such I can't even start to side one way or another. Maybe someone who had the stumble but upgraded to a higher performance clutch system may be able to shed some light .
>>
>>
>>Peter

Yea, that would be nice to know, but I haven't heard of anyone with a new clutch yet. I know others have aftermarket/upgraded ECU's and the problem still exists. Also, people who have done the pulley have reported the problem is still there but better - again probably becase they have more power on the bottom with the pulley installed so they get better clutch slip.

 

<<<There's no combination of gas/clutch work that will prevent it other than simply avoiding full clutch engagement in first gear>>>

Actually, I found something that *kind of* works--although it generally helps only *after* the initial start up and engagement lurch when the engine is cold (I have yet to find ANYTHING that will help that). If I bring up the RPMS and feather the clutch (I know, I know...) then depress the clutch a wee bit more right at engagement while simultaneously getting off the gas, then release the clutch fully and hit the gas slowly. It's a super low RPM takeoff, and I'm sure i"m killing various parts of my car, but when you need to get going without bucking and stumbling, it's the only thing I've found that helps the problem. Of course, I don't think driving a car should take quite so much coordination...

I have an appointment to take mine back to the dealer at the end of the month because my cold start has magically returned (my situation is now considerably worse than it was before the 33.2 upgrade). Maybe they'll know more about this soon-coming fix?

 

New news at last. There was a big meeting in Atlanta last week for dealers and reps from Germany. My dealer in Dallas said that BMW acknowledged that the stumble problem is caused by two things - the heat in certain parts of the US (duh!), and the unusually high alcohol content of the gas in some parts of the US. The ECU is not programmed for the combination of those two things.

Apparently they are working furiously on it as they now know that by mid July we'll be in a worse case scenario. Many of the dealer reps spoke up about their customers' complaints especially in Texas and Florida.

The bad news is that we are still weeks away, worse than when I first got an estimate from MINI to fix this thing.

Apparently MINI is going to send us a letter informing us on what they are doing.

Stay tuned! And practice that clutch technique!

Graham

 

>>New news at last. There was a big meeting in Atlanta last week for dealers and reps from Germany. My dealer in Dallas said that BMW acknowledged that the stumble problem is caused by two things - the heat in certain parts of the US (duh!), and the unusually high alcohol content of the gas in some parts of the US. The ECU is not programmed for the combination of those two things.

I'm very skeptical with this determination. For starters I'm in Toronto and while the last few days have been 85+ my stumble started the SECOND I got upgraded to software 33.2 (I believe) which was 1.5 months ago when we were in the mid to high 60's. Not hot by any imagination. Secondly most Canadian gas retailers do not have Ethanol in their gas with the exception of Sunoco which has no more than 10% which is the maximum allowed by automobile manufacturers. 10% ethanol in fuel has been common since 1970! And no cars should require any modification to run an E10 (10% ethanol) fuel. Regular gas isn't suppose to have more than 10%. I've tried brands of gas, several of which had no ethanol added (Esso 91 Octane as an example) on days that were at maximum 65 degrees and the stumble was still there and VERY noticable.

I just don't buy this explanation.

MINI really does need better QA on their software releases as this is getting crazy!

Paul

 

Do you think there is some smoke screen then? My impression is that BMW Group has got a real problem, and they are struggling! I say test this ECU right where we are all having a problem. Drive our cars, see how this sucks!

Graham

 

Hi Graham...

Thanks for the update (and thanks again for all the legwork). "Weeks away from a fix" is still better than an unknown. Although I do hope that they take enough time to get it right, rather than using our cars as test subjects. Given this news, I don't know what to do about my car. I have an appointment for the 30th to re-check the stumble (and my cold start is down to a morning-ly occurance, worse than before), but if there's nothing they can do at present, I don't know if I should bother. I'm going to have to go in for an oil change in early/mid July before I drive X-country (at 9280+ the computer says I still have 3100 miles til service, but I don't buy it) so I don't know if I should just wait til then.... on the other hand, maybe they can do something to make it a little less tedious for my drive, and I can get it taken care of when I get back... hmmm... decisions.

It's good to know that they're working on it, but also a little frustrating/scary based on Paul's opinion. I reiterate: I just hope they get it right (and figure out the *real* problem) before they release it.

 

OnToast, I've got to tell you this is freaking me out too. I just spent $720.00 to match my ECU to the pulley mod, and, while the result is stunning, I still have to have downtime after BMW/MINI fixes this to get the ECU remapped. Not much cost, but total frustration. BMW Group stuff should work out of the box!

Graham

 

I spoke with someone at MINIUSA, today, and I was given the same information. The stumble/hiccup is caused by the change in the gas from winter to summer blend and higher temps.

Not sure I buy the temp explanation, because it has been very cool for us this spring, and I've had the problem from day one. I also took the car to the mtns where the temps were in the 40's and 50's F, and I still had the stumble.

Gas blend? Maybe. I guess we'll see.

I asked for an ETA on the new software and was told they don't have one, yet. I asked for a best guess, and I was told 30-45 days.

See ya,
JS

 

Isn't it only the lastest couple of releases that experience this problem? This car has been on the market for over a year, right? Without the problem?

I can certainly understand, though, how they'd prefer to blame the weather rather than software developers! Kind of an embarassing admission.

Hope it's figured out quickly in any case. I'd love to think that sometime soon another release'll come along that leans it out and produces more power for free

Jeff