I've noticed that when temperatures dip below about 20F, and especially below 10F, boost seems to cut back just a bit. I'm talking 5-10hp or so. Pre "warmup" this is expected. but once the car gets up to temp and I'm cruising on the highway at 80 mph, less power due to cold temperatures seems counterintuitive. Once ambient temps get up to 30-40F it's in it's "happy zone" again.

Thoughts? Is the large gap between intake temperatures and EGT's causing the ECU to dial back boost? Just curiosity as it seems perfectly normal, just wondering why ha ha.

 

Cold air is denser and more oxygen rich than warm air. The Engine Control Unit reduces the boost because it uses data from the mass airflow and intake temperature sensors to maintain the optimum fuel/air ratio for any throttle setting and prevent lean running conditions. You are not loosing power, just a little boost.

Dave

 

Ah ha! I figured it was something like that. Thank you. I always thought frigid air, let's say below 20F, would be super dense and be capable of creating more power with said volume of air. But a stock ECU is more interested in maintaining correct AF ratios ect I guess...

 

Yup, the DME calls for more boost when necessary so you'll see less in colder weather.

 

There is something programmed into the ecu. If it's 50+ degrees outside i get 20psi (manic 2+). If it's 49 or lower i get 15 psi. And yes it's a noticeable power decrease. I've learned to live with it.

 

I've noticed that 50F seems to be the sweet spot for making power. Anything above 85 and it's dealing with heat soak (hard driving only). Stock intercooler is fairly undersized. I'm really tempted to get a P3Cars digital gauge so I can keep tabs on coolant temps (really MINI?? c'mon), boost, oil temp, EGT's ect... Pretty slick piece of kit. I plan on getting a dyno tune at BrenTuning in the spring, pretty much a must if I go that route...

http://www.p3cars.com/mini/p3cars-mi...tal-interface/

 

i read an article (i think it was on motoring.com) that explained how mini operates the turbo

basically, it is targeting a torque vs rpm map ... if the temp is high, more boost is needed to match the map ... as the temp drops the boost needed to match the map is less so the ecu dials back the boost via the wastegate

in essence the ecu maintains constant power vs rpm via varying the boost as the temp varies

i am guessing that the custom tunes get most of their power by changing the torque vs rpm map

 

i have a scan gauge 2 ... one of the "gauges" it can display is horsepower

the horsepower is the same on a 100F day as on a -10F day, but the boost is lower

fuel flow and afr remain the same as the temp changes

interesting info on fuel flow ...
fully warmed up, fuel flow is about .2 gallons per hour at idle ...
a cold start at -10F results in an initial idle fuel flow of 1.5 gallons per hour!

the fuel flow decreases rapidly as the engine warms up

 

both previous posts are what i have seen on my all4 with the N18 engine

 

This is typical. A cold engine requires a whole lot more fuel than a warmed-up one. That's a big reason you want to try to combine errands rather than let your car go through the warm-up stage multiple times in a day.