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Discussion Starter #1
I described this problem in another thread, but I think it deserves its own thread.

Basically this is what happens. When slowing the car down with any forward gear engaged (using brakes or with engine braking), the car does not decelerate smoothly. When the revs drop just below ~1400rpm, the car surges forward slightly for a brief moment. I don't think it actually picks up any speed, it just doesn't decelerate as much during that point. Kind of like what happens if you hit the gas while you are braking steadily. This is really annoying and potentially dangerous. I always have to anticipate it while braking or I will overshoot the stopping point by a few metres.

Is it a common problem or just my car? Any fixes? The problem seems to be in the engine/supercharger and not the brakes as there is no such problem in neutral.
 

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I think MINIs normally experience the opposite of what you're describing...as the revs are falling past ~1400RPM region, the engine suddenly "kicks" harder with a heavy engine braking effect. Although I suppose the kick could feel like a surge...not sure if the stopping distance would increase since I just use the brakes as normal and ever since I discovered it, I began letting the clutch in earlier (before it happens) as I'm stopping.

As far as I know it's common/normal...for MINIs... :confused:
 

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Discussion Starter #3
Mine definitely surges forward rather than slow down quicker. I hope there's a fix for it, coz there are times when I don't want to put the clutch in such as approaching a give way sign at an intersection.
 

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I think "stutter" or "lurch" better describes it?

It happens to me at 2,000rpm in 2nd, and unfortunately an ECU upgrade has not fixed it (although it did make power delivery smoother).

In this thread Wobert suggests it is fixable and that in his case it related to the fuel cut-off.

I am currently chasing a fix for my own MCS by ringing around the London dealers, as the staff at my own dealer locally are a bunch of muppets.
 

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It most likely is due to the fuel cut-off when decelerating. As you stated, in 2nd, it's around 2000 rpm when you feel a lurch foreward. Higher gears seem to be at a lower rpm. My other car (Honda Insight) also does this when coming out of fuel-cut mode.
 

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yep, mine does it.. every time

it seems quite common so i dont think anyone's really annoyed by it even tho we all talk about it it's the stumble, and yoyo that gets most attention
 

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kyriian said:
yep, mine does it.. every time

it seems quite common so i dont think anyone's really annoyed by it even tho we all talk about it it's the stumble, and yoyo that gets most attention
Ya... you're right... doesnt really bother me that much...
 

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It's the idle fuel kicking back in. When you decel with the car in gear, all fuel is cut to the engine to reduce emissions and improve fuel economy. But as the engine speed slows, eventually you have to start feeding the engine idle fuel or it will stall. Nearly all FI cars do this, although some are smoother than others.

It is a bit of a bother, but assuming the car is running as most do, it is as incredible stretch to call it dangerous or to characterize it as the car surging forward.

I just put in the clutch about at the point where it does this. No big deal.

- Mark
 

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Discussion Starter #10
According to the other thread, v38 of the software will fix these problems. My car was built in may.. i thought it would have the latest software already?

I have driven many manual cars and none of them have this problem. It may not be severe, but I noticed it right away on my first drive home. I am very disappointed that a supposed 'driver's' car the mini have not got these simple things sorted out.

Another thing I noticed is that this lurch happens at a higher rpm when the air con is switched on.
 

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First noticed this after an ECU upgrade from CD32 to CD36. Does it in every gear at about 1200 rpm if I let it coast down that far and it does annoy me.

I had a rather pronounced yoyo that CD36 took 80% away, but added the slow down stumble. I'm intending to have the ECU upgraded to CD38 next time it's at the dealer and hoping it all gets fixed.
 

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Guys, had the dealer load the latest software last friday, deceleration stumble still present :(

My 03 MCS has been doing this deceleration stumble jerk pretty much since new, and this is its 2nd software update. The first time, V37 was loaded and fixed the "first pull-away after starting stumble" and most of the yoyo.

As with V37 the car now feels different, pulls away from stand still with less effort and has what feels like a beefier mid range. Hope this change in character wont disappear sometime down the track like the V37 did.

Anyway im gonna take the car back to get this looked at again. Anyone actually got their stumble fixed with V38+ unlike me!?
 

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My ECU is also upgraded (version unknown but presumed V38) and whilst the characteristics are slightly diminished the lurch is still obvious to driver and passengers.

Interestingly, my dealer arranged for a Regional Manager of some sort (job title unknown) to come down to witness the problem. He acknowledged the issue first hand. Then, we went out in another 03 plate MCS which they had arranged to make available, and reproduced the exact same problem with exactly the same characteristics.

I've been told that therefore, this is a standard "feature" of the MINI and that there is nothing wrong with the car and this is "normal behaviour". It was suggested that I've becomed "accustomed" to the problem and so it is more apparent when I should just be ignoring it.


Basically, I'm aghast that they've acknowledged a problem that they say is standard for all (non-JCW) Cooper S vehicles.


Am I really that sensitive a driver that I've picked up on something I should ignore? Drove a Ford Fiesta at the weekend... there's no stumble in that car!


Don't really know what to do now :(
 

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beej said:
Am I really that sensitive a driver that I've picked up on something I should ignore? Drove a Ford Fiesta at the weekend... there's no stumble in that car!
It's definitely not a matter of sensitivity...it's a really noticable jerk when in lower gears. When I got really fed up with it one day and mentioned it to a friend and demonstrated it, he told me that he's always assumed that it was my driving and I was doing something funky with the clutch :rolleyes:

It really only becomes a noticeable aggravation (for me) when I get stuck in traffic and keep passing through that range during the continuous accel/decel in 1st or 2nd gear. Other than that, I don't really care other than the fact that this and the other funky drivetrain ("characteristics") can really make you look/feel like a crap driver :( In normal driving, I usually have the clutch in before it happens while I'm braking.
 

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I have JCW kit and dont have any problems and thinking back I cant recall it doing any of the things described here before the JCW kit was fitted..must be frustrating as hell though!
 

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My car does this as well, and it is indeed the fuel cut-in. The engine management system will cut off fuel supply to the cylinders on decel under certain conditions in order to save fuel. When the engine approaches idle speed, the fuel supply is turned back on, which naturally creates a bit of a surge as the engine goes from being dragged along by the wheels to making power of its own again.

Certainly it could have been done more smoothly in terms of calibrating the engine management software, however I don't know if I'd describe it as a problem as much as just an annoyance. It's certainly not abnormal, if your definition of normal is "they all do that." :)

Not particularly pleasant, but not abnormal either. :)
 

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I have the same problem too. As Beej said, when slowing down with the car in 2nd gear there is a stumble or lurch at 2,000 rpm. The same happens in 1st, and in 3rd gear the stumble is at about 1,250rpm. It is a bit of a pain, and I try to counter it by keeping an eye on the revs and briefly letting off the bearks a bit as it passes 2,000rpm. Im not sure if it is an ECU problem, but Im a little nervous about having the new software installed, as I have heard a few horror stories on the subject! I would hate to take the car in for this problem and get it back with a worse, new problem (like the rough idle and stalling).Im pretty sure I can live with it, although it does become frustrating on long journeys. Im also sure that my passengers wouldnt mind a smoother ride too! Not sure what to do...............

PS: I wrote this in a hurry (its very late here!), and for some reason the spell checker is having some problems and thinks that every single word is spelt wrong! Therefore, appologies for any spelling mistakes.
 

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Very weird!!! :confused:

I've just started getting this problem yesterday and have never experienced it before. I had the most recent software installed about 2-3months a go and have also recentlly had both fuel sender units replaced (due to a faulty fuel gauge) but the problem has only just started. In a seperate incident, I have noticed that the first few minutes of driving when the engine is cold that the car seems to bog down a bit - like there isn't enough petrol getting though or something similar.

Glad to hear I'm not the only one experiencing this problem.

I'm no mechanic but could it be due to a change in wheather? because the car has a self learning ECU does this mean it is trying to over compensate with fuel so the car will idle higher when the engine is cold?

Any thoughts?

Cheers, LB.
 
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