EVAP leak - now with pic
03-12-2008, 01:40 PM
#11
Here's my take...
Inside the suction pump, there are two one way valves, each only allowing vacuum into the suction pump and brake booster.
The only thing I can think of why Audi did this was so if you're ONLY under boost for a REALLY long time.. like doing 170 on the autobahn, or more likely left foot braking on the track and always staying in boost... you could run into a situation where you use up the vacuum in the reservoir, and it can't get any more with the engine boosting. The accordion hose is under mild vacuum when engine is under full boost, so in that situation maybe that would provide enough vacuum for the brakes.
As long as there's still a one way valve in the 01+ S4s in the elbow at the firewall like there is in the 00 S4, I don't see why the whole suction pump can't just be tossed.
The only thing I can think of why Audi did this was so if you're ONLY under boost for a REALLY long time.. like doing 170 on the autobahn, or more likely left foot braking on the track and always staying in boost... you could run into a situation where you use up the vacuum in the reservoir, and it can't get any more with the engine boosting. The accordion hose is under mild vacuum when engine is under full boost, so in that situation maybe that would provide enough vacuum for the brakes.
As long as there's still a one way valve in the 01+ S4s in the elbow at the firewall like there is in the 00 S4, I don't see why the whole suction pump can't just be tossed.
03-12-2008, 07:02 PM
#13
WARNING: '01+ S4s may not have the check valve in the elbow at the firewall!
If this is the case, the suction jet pump cannot be deleted unless the elbow at firewall is replaced with part from '00 S4 with check valve built in!
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