Hi Guys! I have a N14 powered Mini.
I have solved a few problems since I got it. The car had an intake air leak (it was stuttering very bad) from the PCV so I blocked that off. Now the car runs fine, sounds fine, but always at the same exact 2000-2500 rpm it hesitates like it looses boost.
The worst time it does that, when you are accelerating lightly in 2nd gear, it feels pretty strong, and at 2000 RPM the car becomes N/A . I have not found any boost leaks so far. The vacuum solenoid for the wastegate works, I checked it by removing
the line and holding in the end of the tube to check if it was sucking air and it was.
As for the wastegate actuator I don't know yet, I haven't checked if it was moving or not.
I have monitored live data, and nothing seemed off. Actually one thing I couldn't figure out was the solenoid valves' percentage. The blow off valve showed 100% after every shift (as it should, i heard it because i have a forge bov installed). But the wastegate solenoid was showing 94% on idle, and the lowest I could get it was 23%.
Shouldn't it be at 0% while accelerating?

 

Maybe. But maybe not. With other boosted (turbo-charged and one super-charged) cars the amount of boost is not always max'd out. Techs told me the engine controller seeks to deliver the torque the driver is requesting and signaling by the amount of throttle. If the nominal boost is say 0.7 bar -- as was the case with one of my turbo-charged cars -- one might only observe 0.6 bar boost. To get 0.7 bar of boost -- which I managed to get -- required "idea" conditions. And I had to floor the throttle. Boost climbed and reached and stayed at 0.7 bar but the car was gaining speed at a very fast rate and well, I won't tell you at what speed the car obtained.

The flip side is the engine controller can allow more boost if necessary. With this same car at high elevations -- 8000 feet to 9000+ feet above sea level -- flooring the throttle had the boost climb to 0.8 bar even 0.9 bar and these were not glitches. The boost stayed at these readings for some time before as the speed increased the engine controller decreased boost.

The techs told me this is normal. As long as there are no reasons the engine controller should limit boost (insufficient octane of gas or something else) more than nominal boost can be allowed to happen.

The point is the waste gate solenoid percentage at 23% was probably all the boost necessary to satisfy the torque you were demanding.

The drop off at 2K can be a boost leak on the intake side but it can be a boost leak (exhaust leak) on the turbine side. Or it can arise if the engine controller detects a problem -- detonation? -- that requires it to back off so to speak. Doesn't have to be detonation. Could be inadequate fuel flow or even air flow.

I had my Dodge Challenger -- with its super-charged 6.2l V8 engine -- engine filter changed at 27K miles. I saw the old filter. It was filthy. On the way home I couldn't help but notice the engine was running better. It was clear I had let the engine air filter go too long. I should have known better. While "only" a 6.2l engine with its max output of 707hp this is over 300hp *more* than a previous car of mine that was fitted with a 6.0l naturally aspirated engine rated at 400hp. Clearly the supercharged engine to produce more power needs more air. And needs its air filter changed more often than every 27K miles...

I mention the above to give you an idea of how not so obvious things can play a big role in engine performance. Or lack thereof.