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Second Air Injection giving pulses in the intake??
Background Info:
- working on a 2007 Bentley Continental GT with an Audi/VW W12 turbo engine
- vehicle idles rough/chugs a minute or so after start up - working on fixing this issue
Today's clueless question:
- In my mind, I am going to ask a clueless question.... but hey.... we all have things we understand and don't understand. So here goes the "I am not sure" question:
- little background first
- before starting the car I put a mechanical vacuum gauge on Bank 1's (i.e. right side of car) intake manifold
- when I initially start the car up from cold (i.e. been sitting 10 hours), the rpm's go up to about 1100 rpm and the intake manifold pressure is about
negative 0.4 bar (guessing that is about 14 inHg). While the intake pressure is at - 0.4 bar the needle is steadily bouncing back and forth around the
negative 0.4 bar mark on the gauge. Once the SAI injection pump shuts off, the rpm's settle in at about 750 rpm and the needle on the vacuum
gauge goes to a STEADY -0.6 bar (guessing around 18 inHg).
- CLUELESS QUESTION TIME - when the vacuum's gauge needle is bouncing around the -0.4 bar is this because I am seeing the pulses from the SAI pump shoving air into the combustion chambers?
As always, thoughts appreciated and thanks in advance.
