I have been searching the forum and am getting varied threads in response. I have recently added a 17% Alta pulley, MSD coil ,wires, colder range plugs to a stock 140k 04 MCS. It runs great but when I nail it into the upper rpm range I get a cel and my asc light comes on and stays on. Asc light goes out on restart and cel goes out after a couple of starts. I have replaced vacuum lines and even put a temp boost gauge on ( only goes to 15 psi) . When I nail it in 2nd or 3rd it goes way past 15 psi and cel comes on. I am not a newbie to performance but am to Mini or any import. Any help would be much appreciated.

 

Put your stock plugs wires and coil back on and see if it happens, then one by one take them off to narrow it down. If it still does it with the stock parts you have something else wrong.

 

How far is "way past 15 PSI?" You could be simply running into an overboost situation which will set a SES light and DSC light.

You need a gauge that reads at least 20 PSI, I see 16-17 PSI depending on my surroundings and rev range.

 

I am looking at a better gauge now but was testing with a MAC tool vacuum gauge . Went 1/4 to 1/2 in past 15psi. I am getting codes p1237 & p0108. Other than codes it runs great. This weekend I am going to recheck all vacuum lines, intercooler boots ,map sensor connections and go over all pulley items installed. So any other things to look at would be helpful.

 

The gauge you were using is only calibrated to 15 PSI so anything past it is a crap shoot, you'll need to get a proper gauge plumbed in that reads at least 20 PSI.

Check the MAP sensor on the intake manifold for exposed or chaffing wires, the chances of you causing sensor failure just by replacing the pulley is very small.

Start with getting the actual boost numbers, was there a P1688 present with these codes by chance?

 

For P1237 code, this guy here was a vacuum leak at the bypass valve. I'd inspect it and see what you find as a few threads pointed to it for that code. For P0108, here and here (similar to your issue) was the TMAP sensor. I'd check on those suggestions and see what you find. Good luck.