Stage III Homebrew overboosting problems, part 2 help needed. See the linked message I posted
12-20-2007, 02:52 PM
#1
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Stage III Homebrew overboosting problems, part 2 help needed. See the linked message I posted
at VIR in November. Since then I replaced the N75 valve and the overboosting problem is back just like with the old N75 valve. I ran the MBC only for the last month and there were no overboosting issues at all. I just prefer the drivability of the MBC in parallel.
BTW I have a TCD and KO3 X software. The car was running great then one day after parking her overnight and all was well and the next day it started overboosting as it still is. WTF?
Any ideas this is frustrating, Thank You!!!<ul><li><a href="https://forums.audiworld.com/s4/msgs/2736402.phtml">https://forums.audiworld.com/s4/msgs/2736402.phtml</a</li></ul>
BTW I have a TCD and KO3 X software. The car was running great then one day after parking her overnight and all was well and the next day it started overboosting as it still is. WTF?
Any ideas this is frustrating, Thank You!!!<ul><li><a href="https://forums.audiworld.com/s4/msgs/2736402.phtml">https://forums.audiworld.com/s4/msgs/2736402.phtml</a</li></ul>
12-20-2007, 03:56 PM
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something is either wrong with the wastegate or the MBC.....that sux for sure.
Doubtful it's the MBC since you replaced it once....soooooo......that leaves a problem with the WG is my opinion. Good luck!
12-20-2007, 05:16 PM
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The MBC was working fine as was the Wastegate when running MBC only.
The problem starts when I run the MBC in Parallel withe the N75 valve (including the new N75 valve brand new I just installed today.)
12-20-2007, 05:24 PM
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It goes as far as the boost gauge shows, 25 psi is the last number and it wraps around towards 6:00
guessing 30psi or more. I know the turbos don't like it because they start to squeal so I obviously try not to push it when it is overboosting.
If you go WOT or get into boost quickly (especially at low rpms where it is known to overboost at times) in 2-6 gears it does the described overboosting every time.
If you roll into boost slowly at about 7psi you can hear some sort of whistling or surging and it always does it 3 times, then once you hear the final surge/shistle/noise/etc it will hold boost at whatever the MBC is set at until redline and it tapers as expected????
Does this make any sense or do you have an idea what I mean? I tried videoing it tonight but you can't hear the noise/surge. It is really hard to explain what the car is doing. The crazy thing was that when it first showed up I didn't do or change a thing???
I was convinced it was a bad N75 but no go.
BTW Verruckt I will call you tomorrow~
Thanks!!
If you go WOT or get into boost quickly (especially at low rpms where it is known to overboost at times) in 2-6 gears it does the described overboosting every time.
If you roll into boost slowly at about 7psi you can hear some sort of whistling or surging and it always does it 3 times, then once you hear the final surge/shistle/noise/etc it will hold boost at whatever the MBC is set at until redline and it tapers as expected????
Does this make any sense or do you have an idea what I mean? I tried videoing it tonight but you can't hear the noise/surge. It is really hard to explain what the car is doing. The crazy thing was that when it first showed up I didn't do or change a thing???
I was convinced it was a bad N75 but no go.
BTW Verruckt I will call you tomorrow~
Thanks!!
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12-21-2007, 08:30 AM
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That's strange. Is your MBC set correctly? Loosen it up until it really starts to bring the boost
down.
Did you plug the bleed hole in the MBC? You should if you are running it in parallel.
I would suspect you have a leak in one of your wastegate lines, or your MBC is bad.
Did you plug the bleed hole in the MBC? You should if you are running it in parallel.
I would suspect you have a leak in one of your wastegate lines, or your MBC is bad.
12-21-2007, 10:15 AM
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I got a new MBC that has a check valve so I assume it is working properly.
Why would the problem not show up if there was a WG problem when I was running MBC only?