Fluctuating Boost
10-20-2007, 12:41 PM
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Fluctuating Boost
So Boost fluctuates between 15 and 18PSI at WOT. Logged and saw that the boost valve duty cycle fluctuated as well. I'm wondering if the readout for the Boost Valve Duty Cycle is what the valve is actually doing, or if this figure is how much the ECU requests from the valve. If I can answer that then I'll know whether its the N75 of not. Anyone have any idea?
10-20-2007, 02:17 PM
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Tested an looks like I Have two bad 710Ns!!!!!!!!!
Could I be doing something wrong? I used a cut up innertube to put pressure on the boost side with them out of the car. One pops open at 10 PSI and the other at 15!!!!!! I thought the 710Ns could handle the pressure? Its strange because I can feel them pop open as if vacuum was applied to the nipple. What do you guys think?
10-21-2007, 09:05 AM
#6
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keep in mind that when installed, there is opposing pressure from the vacuum hose side. if you
can push in the diaphram and cover the nipple with another finger, the diaphram should stay open. this will test to see if the diaphram is ripped/damaged.
the difference in pressure is interesting. did you try your test again or just once. i've read that the first time after sitting there could be a little "sticking" of the seal and additional tests for cracking pressure would be more consistent.
the difference in pressure is interesting. did you try your test again or just once. i've read that the first time after sitting there could be a little "sticking" of the seal and additional tests for cracking pressure would be more consistent.
10-21-2007, 02:35 PM
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the diaphram does stay open with the nipple test, and was i able
to make air blow past the pressure side numerous times in a row. So when under boost, there is vacuum on the intake side, leading to the Y-pipe right? This would pull the diaphram closed tighter right? Can anyone confirm that what I'm seeing is normal or a sign of a bad DV?
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10-21-2007, 10:14 PM
#8
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the side leading to the y-pipe is going to be close to atmospheric pressure. there will be boost
on the nipple (manifold pressure) which will close the diaphragm tighter.
look at the link below. 10-15psi is <b>high</b> for a Bosch valve. even the "upgraded" TT and Porsche valves were < 10 psi to crack the diaphragm.
if they pass the nipple test, i think you're good to go.<ul><li><a href="http://dv.mistertam.com/7.htm">http://dv.mistertam.com/7.htm</a></li></ul>
look at the link below. 10-15psi is <b>high</b> for a Bosch valve. even the "upgraded" TT and Porsche valves were < 10 psi to crack the diaphragm.
if they pass the nipple test, i think you're good to go.<ul><li><a href="http://dv.mistertam.com/7.htm">http://dv.mistertam.com/7.htm</a></li></ul>
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