I now have about 400 miles on my '05 Cooper S Convertible with manual trans and limited slip, and I love it! But I do have a question that I hope someone can answer. I have noticed that there is a slight but perceptable change in the power curve at around 3500-4000 rpm, particularly in 1st and 2nd gear. It's hard to put my finger on it but it just feels like it very slightly (but smoothly) reduces its rate of acceleration between 2500 and 3000 RPM. No misses, engine sounds normal, etc. Is this the norm for a Cooper S with manual trans?

I also notice a very slight lag when starting from a dead stop, no doubt due to the supercharger. It will take a little time to get used to this (so far I sometimes tend to either slightly under- or over-rev on takeoff). But I see that in the latest Motor Trend issue, in their Long Term Verdict article on the Cooper S (extremely positive, by the way), they commented on the same thing: "The Mini has a noticable lag off the line, requiring a learned technique for swift, non-NHRA-grade launches without hesitation or clutch roasting."

Other than the question about the power curve, I love my new Mini! I've had my original Mini Cooper for some time (a '74 Innocenti Mini Cooper 1300 Export) so this is a bit of a change for me - it seems absolutely huge compared to my classic Mini! But I continue to be amazed at how good a job they did transferring the "character" of the old Mini to the new. (And I feel much safer putting my 6 year old in this one!) I have already replaced the headlamp bulbs with Sylvania Silverstars. Next will be the K&N filter mod (https://www.northamericanmotoring.co...hlight=RU-1520) and a 15% smaller pulley, but I think I'll wait until I get about 1000 miles on it to do that.

 

I'll like to hear your impressions about the Silverstars,and whether you feel there is any noticeable improvement in the light output and forward visibility.

 

Hmmm. Doesn't sound like anything I've noticed on my 05 MCS (hatchback). Is this at WOT (wide open throttle) or partial? To be honest, I haven't paid lots of attention to how the car accelerates between 2500 and 3000. If I want to accelerate in that rev range, I'd probably downshift!

Yeah, I've had some difficulty with this, too, but after driving the car for about 3 months, I've gotten pretty good at pulling away quickly without either killing it or spinning the tires. Apparently, the pre-05 models, with their taller gearing, were even worse about this than our cars!

I reallyreallyreally love my car, too! As a former owner of several British Sports Cars (MGA, 2 Triumphs, a Jag, and a Healey) the car seems to me to have some sort of "British" magic about it,* but it's especially nice to hear that a classic Mini owner feels a connection to the tradition!

* Just one question: where's the oil stain? How can it be a real BSC without an oil stain???

 

Does turning off DSC make any difference?

What I am having trouble getting used to is how it holds the throttle slightly when you let off the gas between shifts. Must be a fly by wire thing.

 

Sorry, late at night and I wasn't proofreading... the problem is around 3500-4000 rpm, not 2500-3000.

 

If anything the "lag" is due to the throttle by wire gas pedal. It will take a little practice to minimize this built in tendency.

Your perceived lag at 3500-4000 rpm range is interesting in that it is not in the low rpms that others have most noticed hesitation or lag/delay. I wonder if it is a point just after shifting when you need to build up rpms again.

For example, you are in 2nd at about 4500 rpm and shift to 3rd but not accelerating too fast, then your rpms go down to about the 3500 to 4000 rpm range and you don't have much power which you perceive as a weak power curve.

So, try this. Stay in the lower geat a bit longer up to 5000 or 5500 rpm and then shift which will lower rpms down to the 4500 range where there is plenty of torque and HP.
Besides burning more gas, how does that feel? Any better? Many of us shift for performance about 6000 rpms while others shift for economy at about 3000 rpm.
If you are accelerating fast then you can shift a tad earlier and not linger in the lower rpms but if you are maintaining your speed or gradually increasing then you may feel that there isn't as much power.

For the best performance you want to using your gears and be at about 4500-6000 rpm as much as you can most of the time.

 

I notice it most in first gear, though, when accelerating from a dead stop. When I get to around 3500 rpm or so, it just feels like the rate of acceleration decreases just slightly (not that it decelerates, just that it doesn't accelerate as rapidly), and then it goes back to normal a few hundred RPM later. It's a very minor change, only slightly perceptible, not severe at all.

I probably wouldn't even worry about it at all, except that I plan to do the K&N filter mod and put on a smaller pulley soon. If there is anything abnormal that the dealer should look at, I should bring the car there before I modify it from stock. On the other hand, if this is normal, I'd hate to drive an hour round-trip to the dealer only to be told "they all do that." :-)

Is the lag you are referring to a similar symptom to what I described? If so, maybe I need to take a closer look at the tach and make sure I'm right that it happens at about 3500 rpm. If what I noticed sounds like the lag that you are referring to, at what RPM is it commonly noticed, and is it typically more noticable in first gear? Is it anything abnormal?

 

The lag from the throttle by wire is going to happen when you slow to a stop or nearly so in first or second gear then you want to go but there is a pause before the throttle is doing it's job. It's most noticable when launching from a full stop.

It doesn't sound like your noticing a slight decrease in acceleration is anything major.
Your new '05 MCS has slightly lower gearing than the older model MCS so that is another possible reason for what you are feeling.

Taller gears in my MCS make for staying in lower gears longer to get to the power before shifting. You'd have to drive another new MINI to see if the other car has the same tendency as you noticed at that rpm in question.

 

Mid-range mapping on the stock MCS is too rich and causes a sluggish feel in the 3000-4000 range. This is resolved by the JCW kit with the new injectors. It can probably also be resolved with aftermarket (GIAC) programming or a program update from the dealer.

 

Thanks. So then this is perfectly normal. Regarding a program update, since mine is January 05 production, I should already have the most recent factory program, right?

 

The MINI's ECU is trying to do alot with the electronic throttle (idle speed control, cruise control, TPS) so it was no small feat to get the programming somewhere near correct. Unfortunately, there was a lot of drama surrounding the development of the ECU, so not everything is spot-on, the car does have some idiosyncrasies. None of which I think are necessarily a negative, just some weirdness.

lhoboy is basically right - the better aftermarket ECU programs tend to give the MINI a more refined driving experience (along with improved power, throttle response, and fuel economy).

Cheers,
Ryan

 

So far I really I like them. There is a noticable improvement in visability, the whiter bulbs look good, and the installation took all of 10 minutes. From what I read, the Silverstars (which are German made) are just about as bright an H7 bulb as you can get and still be street-legal. Unlike similar bulbs, the Silverstars can be found at most discount auto parts chain stores (for about $30-38/pair, minus a current $5/pair factory rebate), which means no waiting for mail order or paying for shipping. This also means that if one burns out, an identical replacement is as close as my nearest Pep Boys, Advance Auto, etc.