C5 mass airflow sensor and smoke problems

[mike12345]

Hi guys,
Hoping someone can help me with a C5 problem
Car is 2001 2.2 HDi

The Mass airflow sensor was knackered as a result of water corroding it. the car performance was the same whether the MAF was connected or not. Car would not pull at all especially uphill and max rpm was 3500 Fitted new aftermarket MAF (Beckermann). Car ran appreciably better pulling reasonably well in first up 4250 rpm but thereafter little power (somewhat like a rev limiter cutting in) (This maybe merely the shape of the power curve that I see falls off around this figure).

In second, pulls poorly until 1800 rpm, then pulls really well to 3000 rpm and falls off again up to 4000 rpm. The power available depends not only on rpm but which gear you're in at that rpm ie presumably load.
Is this a problem with a cheap MAF or is there some other problem eg EGR valve, turbo, ECU etc? Car has done 118,000 miles
Something I noticed before the MAF was replaced was that occasionally the car would produce a great deal of blue smoke which would stop again quite suddenly. The car is using some oil but not excessively and most of the time there was no smoke at all. The smoke was definitely blue rather than black. No smoke at present.
Any feedback on solving theses problems would be much appreciated.

Regards Mike.