What happens (if it were possible) when the dealer installs the V38 for cooper into a cooper S by mistake?

 

You get better mileage.

Seriously, I don't think the dealer's computer allows mixups like that.

 

Yes, I would hope so. This post is related to my question about my Unichip milage results going down the tube. Everything everyone says, including Randy, tells me that the milage should go up and not down:

-Unichip with Powerchip...lean
-Unichip with V38...lean
-Unichip with cooper V38?..

I'm getting 19 mpg with 5% WOT. The rest of the time is "granny speed".

Could it be my new tires? Kumo Ecsta MX? I'm running 38 frnt, 35 rear cold. I was running Piradas at the same pressure.

 

Remove the Unichip for a tank. See what happens to your mileage. That should rule out the tires, etc.

Since the Unichip is a piggyback that corrupts the signals from the MAP sensor and the Crankshaft Position Sensor, it makes sense that it would throw the OBC calculations way off, but it sounds like you used the gas pump/odometer method.

 

What brand of gasoline are you using? I've noticed that the "off-brands" give me noticably less mpg than do the name brands (Exxon, Citgo, Sunoco, Chevron)

Do you always buy from the same station? If so, try a different one.

 

I use BP 93. Occasionally Sunoco 94.