I have an '05 JCW and have thought about getting it tuned. When I pulled the plugs you can see and smell that it's burning rich. I thought getting it tuned to lean it out some would improve mileage and power. I know cars are set to run rich to power the cat.

The confusion is everyone says don't lean it out, it needs the rich mix at the top end. But when I have had other cars tuned they adjust the a/f map and boost through out the rpm range. So that it will be richer at the top where it needs it and stop wasting gas at the low end.

Am I missing something?

 

A supercharged or turbocharged car should never run lean.

 

Lean in a sc car = BOOM!!!
simple.
Turning is much more complex with computers....not just "leaner", but programmed maps for different rpms and temp combo's....not just a jet size like a carb.
but fact is stock maps are a bit rich, and cars can be modified due to this safely...but a few mods, and a tune is needed to make best power...but on a sc car, if you go lean detonation or pig is a MAJOR isdue due to HOT intake temps....readup!!

 

By the way...your description on what a tuner does is ok by my understanding, but not quite as simple....just know a custom tune can make more power...but nothing is free. When my car was tuned, i asked for a good safe tune....others want much more agressive tunes to get every last hp out of their motors......i figure, a little bit of gas, a a couple of hp for MUCH mower operating costs is a good deal...but tune to the ragged edge, and you get a partially clogged injector, boom, or burn a valve...can get $$ fast. Factory tune is kinda rich but you NEVER want to be lean.

 

In very general terms you're not missing anything.

Custom ECU tuning is about "Fuel" & "Timing" and having the optimal amount of both at any given point of the RPM range. People tend to forger that tuning is not about, or does it make, Horse Power, your parts make HP, tuning, when done correctly, creates the optimal environment for those parts to work as efficiently as possible, and efficiency makes HP. That being said, yes there are +/- 's beyond peak efficience that will let you "get a little more" but that is where you start getting into the "danger zone" and risk damaging things.

Yes the factory tunes rich, simply because it is safer to do so for the spectrum of environments that their vehicles may be used in and all the variations of different types of drivers.

If you have a JCW car, it is already, ever so slightly, leaner than the non's, but it would still benefit from a custom tune, simply because, no matter what, the same exact parts will work differently on different vehicles, and again you would be having your car tuned for "your" parts. So as long as you go to the "Right" tuner you don't have to worry about "rich" or "lean" it will be set for what your car needs.

In a nutshell you have to think of "Tuning" as just that....tuning....just like you would an analogue radio, tune the dial to the optimal position for the best signal.
(That's the best analogy I could come up with)

 

Successfully tuning supercharged MINIs is slightly different from tuning other cars. The conventional wisdom is to see the factory pig rich AFRs and take a ton of fuel out of it. Even some professional tuners have fallen into this trap with bad results...

 

Yup, our cars tend to be different than the rest, and that's why not just "any" tuner should do them.

 

I think I understand better. The efficiency can be improved some, but not a great deal just because it's an SC MINI.

I know tuning is more complicated than I described, that's why I leave it to the pros.

My view point was from my WRX after a custom "safe" tune I gained about 20hp with the mods I had on it. The response also improved (less lag) and the mileage went up when I didn't have my foot in it (lower rpms). If you lean these out too much they melt down and go boom.

Yes I'm an old fart but I haven't tuned a carbureted car in 20 years.

Thanks for the advice and any additional insights.

 

Haa, Haa...old fart...you mean:
Brake Torque it
Twist the Distributor till it Pings
Back off a hair
And you're done....

 

All those gains you saw on the wrx ARE there with a good tune, and also less intrustive dsc....
While there are a couple of tune yourself mini kits that have comeout, imo, letting a GOOD pro with a GOOD reputation do the tune is worth the $$. Just let them know your expections....a race tune might make a bit more power, but may not be approprate in engine longevity for a dailydriver for the slight differance in hp.....
but,especially with a few mods, a good tune will make the run smoother with more power, and depening on your right foot, better hp, and better throttle response.
Some folks see a huge difference, some see very little....just depends on the motor.

 

With all of our tuning, it's not about getting the most HP. It's all about maximizing the optimal Air-to-Fuel Mixture to enable the engine to run at it's optimal. Along with raising the torque limiters and ecu parameters, the HP naturally increases.

So if you come across a tuner who says "I can give you 250whp" with your mods... you should turn around and run as fast as you can. A good engine calibrator (good tuner) will only make as much HP as the engine allows it - that's the key. The hardware components dictates maximum output - not your tuner.

What should my target AFR be on gasoline?
Answer: This varies from the type of fuel being used. On 91 pump gas, we like to stay within the range of 10.8 to 11.5 at WOT. Cruising target should be 14.7...

 

Right then pull up the rpms and adjust the fuel until it bogs down. Then back it off a bit. Also none the this walnut stuff for carbon. Give it some rpms and poor some atf in the carb. Lots of cool smoke

Is anyone going to be tuning at the dragon? Would a unichip be worth anything over the JCW tune?