Central Coast Coopers in Oxnard, CA installed an m7 DIFIC on my 2005 MCS today. The major improvements that I have noticed so far are (1) the car has smoother throttle response, (2) I can use one gear higher when going up some long freeway grades and (3) the flat spot is 90% gone

I have had my MINI for 19 months and have always had a "flat spot" between 2800 and 3000 RPM at part throttle. I have tried numerous fixes including an ECU remap, higher octane fuel and nothing has worked. After the DFIC was installed today the flat spot is 90% gone. I am thrilled but can't figure out why cooling the air intake would have any effect. Can one of you out there at least speculate what happened?

BTW, the installation went flawlessly. Matt and Scott at Central Coast Coopers have several DFIC installation tricks The air diverter does not cover any rows of the DFIC and actually allows some air to flow between the hot engine and the ceramic coated bottom of the DFIC. They also used custom, silicone IC boots, which are easier to install and have a better fit than the ones by Alta

 

Very nice to hear LC. Just accept the miracle and go with it

I do question the bit I have bolded though. It'd be nice if there were data proving doing this is better than decreasing the flow through the IC.
I can't but think spilling air under the IC might not be a good thing.
I understand the thinking, I just wonder about the effectiveness.

Please don't take this as poo pooing your coool new toy. I just want you to get the best new toy you can If this works, others will follow

 

Could a cooler air charge prevent the ECU from retarding the timing? Could this minimize the part throttle flat-spot?

 

Cooler is goooood, period. Yes it could prevent timing retard.

From what I've seen timing retard doesn't happen until higher rpms and higher IAT temps kick in. 5500 or more depending on temps. Pretty generalized statement I know but issue is well before I'd expect a knock sensor to fire up. Was it the same winter or summer?

My version of the flat spot is dead on 3200 rpm and is felt only under slow/moderate acceleration.

 

Congrats on the DFIC..... I consider it one of the best mods I have..... i think mine was the 4th produced and I am a huge fan..... others are trying to figure out why it works......I just know it does.....

 

The only engine performance mods where I could feel a difference were the 15% pulley and the DFIC. I did not notice a difference with the CAI, TB nor exhaust.

 

The flat spot is a function of the intake port shape and has nothing to do with an intercooler or its function. (See my web site.)

 

My custom diverter sits under the DFIC and allows a very small amount of air to flow over the ceramic coating. It's not a lot though, maybe a 1/16" gap across the entire width of the IC. By far the majority of the air gets rammed into the IC finned area, with no leakage on the sides or the top.
I never had a flat spot so I can't add to the "miracle" Larry seems to have observed.
cheers,

 

if that is true why don't all Minis have the problem?

 

They all do -- it's inherent in the shape. You can verify it by logging data. And then retest using a modified port shape. But that design change gets very costly to do. (We only tried it once. But if anyone wants to fund more testing please just let me know.)

 

There are many Mini owners that disagree and claim no flat spot.....are they oblivious

 

Correct. It is easily verifiable with an a/f meter. Mini knows about it and has come out with a few remaps. MTH and GIAC works to improve the area. It is nothing serious nor does anyone need to worry about it. It only becomes important when racing.

 

Interesting........

 

A flat spot under light load in the mid rpm range is not unique to the Mini. It happens in many n/a cars at about the same range for the same reason (the MCS is n/a while cruising at light throttle). Ask Dr. O, he has data about this as well.

 

...then how did the addition of the DFIC improve the flat spot?

 

...it didn't! There in lies the mystery, Larry. You had it, and you still have it, but it feels different. Mmm...
The flat spot, the YoYo, and other MINI phenomena seem to keep all of us wondering. Those with lots of knowledge and experience, and those with little of both (I'm in this camp.) Perhaps one day we'll learn the secrets. 'Till then, enjoy the fact that the DFIC makes your car feel better, and presumably, more fun to drive.

cheers,

 

Remember that the intercooler cools the intake air (dissapates heat). Cooler air is more dense, thus more O2. If you have more O2 entering the combustion chamber, you can burn more fuel. The ability to burn more fuel creates more HP.

Since adding more O2 to any engine, naturally aspurated or not, will improve it's performance. The improvement will occur even with the exisiting port design and configuration.

I suppose that the increase of O2 through the "flat spot" would negate the affects to some degree, thus making them less noticeable.

I have the M7 DFIC and I definitely can feel the difference. A recent run up in Lake Tahoe CA at 8000+ feet gave me a real feel for the improvement.

 

Under what conditions do you feel the most and least performance? Do you thin heat soak recovery is faster than with the stock IC? I have noticed the biggest difference on long freeway grades - can use a higher gear

 

what I have heard is that the cooler charge keeps the ECU from executing a routine that exacerbates the flat spot.....(for all the physical reasons)

.... the above explanation could be total BS

what you are experiencing empirically is what your engine is doing....walks like a duck..... no DFIC ... problem.... with DFIC 90% problem gone

 

My feelings on the matter, take it or leave it.

What dmh said about the port shape may very well be partially to blame. However, as we all know, one part of the story is rarely the whole story. For the port shape to affect AFR and throttle response, i.e. flat spot, it must be effecting either a) how the computer is responding to the air it is getting, or b) having an effect based on the quality of the air charge. The ports have a specific flow characteristic, but that flow characteristic can easily change with a change in the properties of the intake charge. We're seeing the same cause and effect to flow with this latest exhaust design. With a higher thermal efficiency comes a lower IAT and lower pressures, and higher density. It's easily possible that the denser, cooler air charge is being handled differently by the ECU because it's flowing differently through the ports, eliminating the response that causes the flat spot. Given that simply adding the DFIC into Larry's system has virtually eliminated the flat spot points to many more factors than just the ports as the cause.

That's my feeling, based on what I know. Feel free to argue the point.

 

It didn't. Nor can it. The flat spot you, me, and Mini knows about occurs in cruise mode: light load, partial throttle, mid 3K rpm range, and normal IAT (where the ECU is not "dumping" fuel to cool the cylinders). It has nothing the quality of air charge. ECU reprogramming and a purpose built header (if you want to go that far) can help alleviate the issue but an intercooler cannot. An upgraded intercooler will help lower the IAT when you are hard on it at high RPM ;but not so much in cruise mode.

 

all that is fine Don except.... with the DFIC, Larry (who is driving the car) says the problem is all but gone..... and your saying (without driving the car)no it isn't.....isn't it possible that there are other factors that you and Mini USA have no knowledge of or have not considered..... there is a long list of things that Mini USA does not know about their product.....I have had to teach them a lot myself.....

 

I think that is what I said...... but I am no scientist

 

As I said ealier, it is not important enough to worry about. If Larry and mini pooper feel that the DFIC fixed their flat spot then great.

 

That's pretty much my experience in my car.
Oddly it occurs just about where my yo yo used to end.
The yo yo at least is history. After 3 years that crap is gone