I just installed the Alta Intake in my MCS and the first gear stumble is FIXED! I can't believe it. Before the install, when I would floor the excellerator from a full stop the power would surge for a second or two and then go (so annoying!) but now it doesn't hesitate at all. I actually screeched the wheels when it took off!

Overall, it feels like it can breathe better and the excelleration is smoother. This was worth every penny!

I did the install myself, which wasn't too difficult except I did have to go buy some degreaser to clean the oil off the inside of the filter before mounting it, as it kept sliding off when I tried to tighten the clamp around it. My only suggestion to Alta is to mark on the instructions which steps are optional if you are not installing their hose to the Throttle body. It kinda confused me until I read it over a few times.

To everyone that doesn't like the stumble, get yourself an Intake!
By the way, OutMotoring.com has great prices and are quick to ship! Highly recommended!

 

I cannot see an INTAKE fixing a software issue.

 

I am very hesitant in believing that the intake would improve the stumble, but since I am not there to witness your results, I cannot comment to much on that.

One note that I do have, since I have been living with this stumble, is whether a simple software fix will correct this issue fully. I know that older versions did not exhibit this problem and I hope they can reinstate those settings at some point in the future. If it is a software problem, why can't a company with this much experience and breadth of knowledge address this issue in a more timely manner? But I digress. One item that I am frusturated with is the poor gear ratio choices and the enormous lack of throttle response. I know that some people have addressed some of the throttle response issues (i.e. ecu, throttle body...), but do all of these things together bring back an ultra-crisp throttle response? Why is it so poor in the Mini. My $10,000 Saturn seems like a Ferrari in terms of throttle response next to the Mini. It is ridiculous. Also, is anyone designing any gears to address the high gear ratios for the Mini? Both of these items would help address some of the first gear bog that the Mini has.

 

As far as I can tell, I have never noticed stumble in my MCS. Very early on I changed out my intake to a Madness- few hundred miles.
Others have reported onset of stumble long after purchase. Initially I was thinking why don't I have stumble- could it be the intake.

An easy way to tell if the intake is doing anything for stumble is to remove the alta intake and put on the stock filter and if the stumble comes back then you have an answer for those who question if the intake makes any difference.

So Ryanide- take off the alta intake- does the stumble return?
Was there something else that was done during the installation of the intake that might have helped to undo the stumble. Resetting of the ECU?

 

Could it be an airflow issue? In other words, the throttle body opens up at initial acceleration. The computer increases fuel flow for the increased air flow it is expecting, but, due to airflow (incoming air speed or volume) problems the air doesn't come. Now you have too much fuel and too little air. Possible flooding issue until the airflow can catch up or the computer can compensate. Stumble. Or, the computer senses the initial over rich situation and compensates by reducing the fuel flow briefly. Stumble.
Now, add the better flowing intake and it can breathe again. Problem solved.

Some people say it is a specific software rev doing it. If the above is true, maybe that rev is overcompensating for the initial air/fuel mixture inbalance and then at the over-rich situation.

Feasible?

Chris

_________________
2003 LY/W Mini Cooper

 

I don't know what else to say, but in my case this fixed it 95%. I previously had to be cautious about giving too much throttle in first gear (in order to avoid the stumble) and now I and full throttle it and pop the clutch without a stumble (although it does make the front wheels spin or screech!).

Maybe it is different for others, but I'm just sharing what happened for me. I have not other mods or did anything differently.

Motor on!

 

Found this post on the Owner's Lounge discussion board:

 

I've been puzzled about this 'Stumble' now for a long time. I consider myself stumble free, however I do get a stumble from a dead stop from a stop light or stop sign sometimes when I don't rev the engine up enough. I know the MINI has a heavy flywheel and this could be why I get that stumble at first. But if I really try to get a good launch, and slip the clutch enough there is no stumble. So is this stumble just a fact of inexperienced drivers with not much tourque and a relatively heavy car? Is there really a fix in the software or is there more of a fix in the brain? Can anyone give me some more insight into this, what the concesus is as to what the problem is?

 

Hey Ryanide, congrats on the fixed stumble! I have been bugging my dealer for the past 3 months asking for a fix. I do have one request. Can you please report back in at least 3-5 days and tell if you have been stumble free. Or if it has been that long since you installed the Intake, I guess that takes care of that. I just want to know about a little long term effect with the intake. Thanks

 

I can attest to the intake helping the stumble first hand. After installing my Rouge intake, my MCS's stumble tendency was dramatically reduced. If I may theorize, I feel the reduced intake restriction and/or increased airflow allows the ECU to do a better job processing its' data, making the engine run smoother as a result.

...this is how hardware can fix a software problem

 

Installed PILO intake a few weeks ago. Perhaps some minor improvements to the Stumble...it ain't gone though.

 

Interesting comments. So for those with stumble please do try a big ole intake- they are pretty easy to try on and see if that at least helps your stumble. I will check with others in my area that have stumble and see if they still have the stock intake or not. Could be an interaction between the aftermarket intake and the ECU to cause a positive effect on the stumble. It's a helpful discovery. Now has anyone taken out their big intake to get the stumble back?
I be too chicken

 

Sure, I'll keep you posted on the status. I have to admit I thought I messed up because I originally tested it after the install with the AC off, which normally helps reduce the stumble. However, I've had the new intake in for a day, and both with the full AC on and with it off, I can say the stumble is almost completely gone.

Originally, when I would supply good throttle and release the clutch quickly (in first gear from a full stop), it would start and immediately drop the power for a half to 1 second then go. I found myself hesitant about making quick left turns in between oncoming traffic! With practice I discovered that if I supply enough throttle and let the clutch out slower, it would excellerate more even and with minimal (or no) stumble. The difference really came down to how quickly I released the clutch. So, I was beginning to believe that this was more about learning how to drive this particular manual although I have driven a stick for 15 years and would consider myself pretty good at it.

Also, I remember the two different S's that I test drove also did this stumble!

Now, with the new intake installed I can pop the clutch quickly and I do not have this drop in power. But what I do have is the DSC or traction control kicking in to stop the wheels from spinning! It is also a bit embarrassing to screech the wheels when taking off! But definately there is no drop in power like before.

I can really feel the excelleration is smoother throught the gears. My guess is that the stuble does have something to do with the electronic throttle, air intake, fuel supply and software. It's really hard to say, but somehow, thankfully, this has helped. I now feel safe to jump a left turn!

Cheers!

 

In my case the Rogue intake made the car run better but I wouldn't say it "fixed" the stumble - that is a "characteristic" of the car according to my service manager.

 

>>In my case the Rogue intake made the car run better but I wouldn't say it "fixed" the stumble - that is a "characteristic" of the car according to my service manager.
Characteristic implies that the majority of the MCS have the stumble. Does your service manager mean to imply this is a very common malady of the MCS, if so then it ought to be a recall. The problem is clear, the solution is not. If I have never ever had the stumble then is my MCS uncharacteristically smooth? I hope not. My car is doing great and I want all other MCS owners to be stumble free so we can get on with the enjoyment of Motorin in peace.

I would NEVER say to anyone that the stumble is characteristic of the car. I know how it might seem this could be so to a service manager who sees the problems brought in with no fix in sight. We should bring in our non stumble cars and tell the service manager how well they are running. Obviously there are both types going on.

In my book, anything that could help is good news short of a magic bullet that cures all woes.

 

Not to be pessimistic, but obehave on MINI2, and I think a few others there noticed the same, only to have it return. It is believed that it takes some time for the ECU to return to this undesirable state after adapting... Also, I think people tend to drive with more throttle after such a mod, to better hear it, feel it, etc. Driving style has much to do in experiencing this issue. Ask Randy how his stumble is

 

I'm still not convinced this is a problem with the car, more a problem with the driver. Yeah, sure, I get a stumble when I have the AC on and I don't rev the motor up enough. If it were a problem with the software, then you would see it at any RPM from a stop, and that isn't the case. There simply is not enough power below 2500rpm to get the car going.

Make sure DSC is off and the AC is off, and you have the engine to close to 3000. If it is a characteristic of the car, which I think it is, then you might just need to relearn how to drive a manual.

 

Minihune-

I've said it before, and I'll say it again. Virtually ALL MCS's that have software either upgraded or initially installed after Spring of 2003 have the Stumble. Virtually ALL MCS's that do NOT have software installed or upgraded after Spring of 2003 do NOT have the Stumble. No, I can't prove it, but this comes from extensive reading of these forums and extensive discussions with MINI owners throughout the Midwest. For a while there, I thought that June-and later-build MCS's were not experiencing the Stumble (check out my Stumble survey thread); and it's still possible that there is a lesser likelihood now to get a new MCS with Stumble "pre-installed."

At the very least, I feel confident in stating that MCS's with software installed during April and May of 2003 have the Stumble. Period. I really wish BMW/MINI would come along and explain why this thing exists and how extensive its existence is, but I'm guessing that legal won't let them. Wouldn't it be nice if they would come on this website, admit that it exists, admit that they're working on it, and give a reasonable ETA of when the fix would happen?

And a final question: can anyone explain how the ECU works? Is it really able to "learn" when changes have been made and adjust itself over the course of X number of miles?

 

>>Minihune-
>>
>>I've said it before, and I'll say it again. Virtually ALL MCS's that have software either upgraded or initially installed after Spring of 2003 have the Stumble. Virtually ALL MCS's that do NOT have software installed or upgraded after Spring of 2003 do NOT have the Stumble. No, I can't prove it, but this comes from extensive reading of these forums and extensive discussions with MINI owners throughout the Midwest. For a while there, I thought that June-and later-build MCS's were not experiencing the Stumble (check out my Stumble survey thread); and it's still possible that there is a lesser likelihood now to get a new MCS with Stumble "pre-installed."
>>
>>At the very least, I feel confident in stating that MCS's with software installed during April and May of 2003 have the Stumble. Period. I really wish BMW/MINI would come along and explain why this thing exists and how extensive its existence is, but I'm guessing that legal won't let them. Wouldn't it be nice if they would come on this website, admit that it exists, admit that they're working on it, and give a reasonable ETA of when the fix would happen?

OK, Lets assume you are correct. If there was an easy fix like simply installing the old version of the software, then if it were a software only issue, it should restore the MCS to it's prior self but this isn't happening based on your account and surveys. So the problem is multileveled and complex. Then the MCS that is worth studying is the MCS built after April 03 that doesn't have the stumble (they must exist- just test drive five new MCS) or any MCS that was built earlier than april 03 that had software updated got the stumble then had something done that fixed the stumble.

Thanks for your theory. I know that if MINI knows about how bad it is- they would try to downplay it. I guess it is time to test drive five new MCS.

 

I read that a guy was persistent in pestering his dealership about the problem and they had his ecu sent back to NJ (the only place that can reinstall old software!) to have old software reinstalled and it worked.

 

I agree with you minihune. If they would reinstall old software, then it would work. But they WON'T install the old software problem (unless the previous post is a fact). If you ask your dealer to install software, they will simply claim that it is impossible--that they can't reinstall old software, or that they don't have it, or some other excuse...

 

Interesting. The Dealers can't or won't install old versions of software? This is 2003 and they cannot do this simple task? We can go to outerspace and back (or we used to) but we cannot do this software adjustment with a known logical solution. If this is really true then I might have to change my opinion about who is running this show.

Ok then, If I have my original ECU and software (built in 10/02) and I have no stumble or other problems at all and I upgrade my ECU (Powerchip or other upgrade). Do I risk getting stumble? Now the good part with this ECU upgrade is that supposedly the original software file is saved and stored so that I can return the software to the non upgraded state it was. Which means if I save my original file and then use it to flash another person's stumble MCS then that should fix their troubles? Does this sound correct or is my software only good for my MCS and no other? Then it can only help me.

 

I took delivery of my MCS on 10/25/02 and it does not have any sort of stumble :smile:
After reading this and MANY other threads on the topic I am shocked that no one has tried flashing and reinstalling an older version of the ECU software. A pertinent series of questions to isolate the problem would be....

1. Has there been any mechanical change in the engine set-up from stumble to non-stumble?

2. What exactly was changed in the ECU software from version to version?

3. If people change the intake and it reduces/eliminates the stumble forever would this not indicate that the fuel/air mixture portion of the software is at fault?

4. If people change the intake and it temporarily fixes the stumble but the stumble returns, wouldn't that indicate a fault somewhere else in either the ECU program or in the mechanical operation of the engine?

5. If ECU upgrades/powerchipping eliminates the stumble then exactly what part of the program is responsible for the fix?

6. Does a pulley upgrade affect the stumble for good or ill?

7. After reading about how the ECU will retard timing to prevent knock/early detonation and how the DCS will retard performance driving to prevent wheel spin; is the ultimate culpret of this infamous stumble a sub-routine of the ECU overcompensating for an imbalance in the fuel/air mixture.

Until these and many more questions are answered I gotta go with minihune and think its a problem that involves mechanical and ECU issues.

 

The powerchips and a lot of the upgrades for the ECU out there are based on your basemap. So it takes the ammount of fuel it is supposed to give the engine and gives it more/less fuel/air based on that. I think that the GIAC ECU upgrade (that's not out yet so I'm not sure) is a whole new ECU so I'm hoping it will fix it.

I think the air/fuel mixture is the cause of the ECU issues. However, I don't think any hardware mod will be a complete solution because of the learning that the ECU does. I'm not sure exactly how it learns but I'm afraid eventually the hardware fix will be "learned" and eventually the stumble will come back. Of course I could be wrong.

rafthos:
1. Some people have done no mods and still experience the stumble so it's not a problem with upgrades.

2. We have no idea what BMW does and I'm pretty sure they aren't going to tell us. They probably changed the ECU map to get better EPA ratings.

3. Yes, but I don't think it's forever, see above. I definately think it's an Air/fuel mixture problem.

4. I think it's an ECU issue as the ECU "learns"

5. The ECU upgrades like powerchips doesn't fix the stumble because it's still based on the stock ECU

6. I'm not sure on this one but I have a pulley and a slight stumble that has developed over time. It's still not as bad as some other people have.

7. Yes and no. It is definately compensating for the air/fuel mixture but I think it's a fault of the ECU.

I don't think it's really a mechanical issue but rather a ECU issue. They need to stop making the ECU upgrades based on your stock mapping and start redoing the whole map from scratch.
-Chris

 

>>We can go to outerspace and back (or we used to) but we cannot do this software adjustment with a known logical solution.

Yep. Now you know why some people are really frustrated. Sol from Perfect Power (an MCO Sponsor--MINI tuner here in Chicago) was one of the people who went in to get an upgrade on his dealer's advice to fix his cold start issues and upon leaving the dealership IMMEDIATELY felt a huge difference, i.e. the Stumble. He turned right around and said "Gimme back my old software!" and they said that it wasn't possible. I think that this is a load of crap, but BMW/MINIUSA must have some reason that they won't let them do it. I can't explain it.


>>Ok then, If I have my original ECU and software (built in 10/02) and I have no stumble or other problems at all and I upgrade my ECU (Powerchip or other upgrade). Do I risk getting stumble?

No way, Jose. As far as I know, all of the existing chip upgrades are based on a download of your existing software which is then tweaked and uploaded back to your ECU.


>>Which means if I save my original file and then use it to flash another person's stumble MCS then that should fix their troubles? Does this sound correct or is my software only good for my MCS and no other?

I've never thought about that before. Since the aftermarket is able to download software and then upload it again, it would only make sense that I could take my buddy Scott's car to Perfect Power, get them to download his software, and then get them to upload it to mine! Perhaps the aftermarket can do a quick end run around the problem. **NUDGE TO ALL MCO SPONSORS** We really should try this!

In response to all of Daytona's comments: I totally agree that it has to be something to do with the fuel/air mixture...it's like for a half a second, the ratio goes to 1:0 and there is no air in the system at ALL...I also like the theory that it has something to do with the sensor that requires the clutch to be depressed to start the car, since this happens at a very precise point in the clutch pedal travel...just thoughts though...

Maxwell