Recently I had problems with the boost so I installed a bleedvalve to control it. But when ditching the solenoid and only using the bleedvalve to control the boost, the spool up time was much faster. When we did a DDash it gave a very poor mixture between 1500-3000rpm.
When I reconnected the solenoid and use back an orifice of 1.25 instead of the bleedvalve my peak boost was 1.25, and with the DDash it was back to 0.85-0.90lambde instead of 0.02-0.07lambda.

The conclusion of this was that when the turbo spool up time is quicker and you don't change the maps, it will run lean on that..

Am I right on this or am I tottaly wrong ????

I ordered now a control valve to control the boost instead of that orifice....

 

If it's spooling a lot quicker higher levels of boost are being reached at lower rpm's and the fuelling is going to be non proportional to the higher boost levels on the standard map.

But then i'm no expert

 

Agree with James.
On the other hand there is no real problem if your mixture is slight leaner below 2500-3000 rpms (no det etc problems in this area). Hope the experts will answer your question though!
JIM

 

Finnaly I got my hands on the Unichip software to check my maps out and geuss what : somewere between all the nulbers there was a zero, just on the revs were I was running lean, so replaced it by a number, go for a test drive and problem solved.

So when you map the car, check the maps three times, just forgot one number and almost blew up the engine...