[QUOTE=jacekowski;10936041]MAF or AMM or whatever you want to call it will not stop turbo from operating.
Lack of power caused by lack of air can be caused by two things, turbo venting into atmosphere - just find where and replace the hose - this will also cause a lot of black smoke so it's easy to diagnose by just that.
Second thing, more difficult to diagnose is turbo not delivering pressure, this can be caused by many things, stuck VNT, leaking vacuum lines, turbo itself being faulty, problems with MAP sensor.
Also, anything that makes car go into limp mode will force turbo to very low boost and very low fuel dose.
Easiest thing to check first is to have a look at the boost gauge, when engine is revved stationary it should move to somewhere around 1bar and then drop down, if it does move but only very slightly, it's either limp mode or problems with VNT.
Limp mode can be caused by a lot of different things, including leaking EGR (quite common problem, however it has to be leaking quite badly to cause limp mode).
Limp mode is very easy to diagnose with a code reader (£10 bluetooth ELM327 dongle) and alfaobd or torque from play store - or just go to a local garage that can read codes for you.[/QUOTE
When towing , the engine didn't stop , simply dropped rev's so low it wouldn't pull the trailer , also showed no boost so was forced onto the hard shoulder ------ immediately I pulled the sensor , the boost returned and was normal in every respect --- I have to assume then that the sensor in some way caused the issue ?? The only other possibility I can think of is that I don't service my car as per ALFA 18,000 mile intervals , I service it between 5000 and 8000 miles . Obviously during the mileage when '' it '' thinks I should service the engine plus lights up a warning --- I ignored it , knowing that it's been done. Could that have dropped it into limp mode in an effort to force me to an ALFA service garage ?
well that's not going to happen