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So... I've been trying to track down the cause of inconsistent boost on my 9000 and have found something interesting. I did some datalogging on a couple of trips recently, and here's an example of what's going on:
That is from an edited log file - the two pulls were actually done about 10 minutes apart.
In the first pull, you can see boost runs pretty close to target, with BCV duty cycle around 75%. In the second pull, the boost runs lower than target, even though the valve duty is 85-100%!
I noticed this behavior yesterday and figured the valve was just dirty (I'm using the stock valve, not a T7 one) so I cleaned it thoroughly last night. The image above is from today... the cleaning seemingly had no effect.
Can anyone think of another reason boost would be lower even though the valve duty is higher? In each case, the lower-boost pull was later in the trip than the higher-boost one, although the engine was fully warmed up in both cases.
_______________________________________
Eric Law
Current collection:
'12 Audi A4 quattro (self-tuned)
'14 Audi A6 quattro (also self-tuned)
Gone but not forgotten:
'72 99, '77 99 (became a turbo, twice)
'80 900T 5-door, '81 900T, '86 900S (became a turbo), '86 900 SPG
'86 9000, '97 9000 Aero
A bunch of Audis, '69 Firebird, '64 Toyota Corona (first car, cost $35 and worth every penny)
Be alert... America needs more lerts!
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