Odd Boost Problem
11-11-09, 09:05 AM
#1
Odd Boost Problem
Trying to get this car sorted and am sort of baffled at this point. Basically, initially the secondary turbo was not coming on. After much testing and setting the boost control back to the stock system which made the car boost to 13 PSi naturely, the secondary came on. Then putting the boost controller back in, the secondary would now come on if there was more then ~11 pounds of boost. Sometimes it also won't come on but the higher the boost, the higher the chance of it coming on. Anything past 12 PSi and it will always come on.
Ok, so now the secondary is coming on at higher boost (which isn't normal). Find another really nasty issue. If the car is reved anywhere past 4k at WOT, and then take the foot on the throttle, and try to boost again, it will not boost past 2-3 PSi regardless of RPM (past 4k) and how many times I push the throttle. The only way to restore boost is to let the RPM drop and it will come back to normal. I tried disconnecting the double throttle in case it was closing for some silly reason but no go. Oh also, when its in this 2-3 PSi state, after I let off the throttle, there is a winding down moo sound after about a second.
I think both of these problems are somehow related. Anyone have any ideas?
thewird
Ok, so now the secondary is coming on at higher boost (which isn't normal). Find another really nasty issue. If the car is reved anywhere past 4k at WOT, and then take the foot on the throttle, and try to boost again, it will not boost past 2-3 PSi regardless of RPM (past 4k) and how many times I push the throttle. The only way to restore boost is to let the RPM drop and it will come back to normal. I tried disconnecting the double throttle in case it was closing for some silly reason but no go. Oh also, when its in this 2-3 PSi state, after I let off the throttle, there is a winding down moo sound after about a second.
I think both of these problems are somehow related. Anyone have any ideas?
thewird
11-11-09, 08:50 PM
#6
One of the vacuum lines between the turbo control actuator and solonoid had a tear. It fixed the problem where there would be only 2-3 psi of boost after you let off above 4k and the moo'ing noise but the secondary still won't come on until a higher boost is reached.
thewird
thewird
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11-12-09, 05:52 AM
#8
No pills are being used as both actuators are t'd into the boost controller. I have also considered this and tried hooking up the BC to only the wastegate control actuator and leave the oem pill in the pre-turbo one but it made no difference. Hooking it back with stock pills is also an unfair test since it naturely boosts to 13 psi.
thewird
11-12-09, 09:13 AM
#9
if the secondary turbo won't come on at all (as opposed to coming on but under boosting), wouldn't that be indicative of the charge control valve staying shut? I would check everything associated with the charge control valve, especially since the it works on a pressure difference. I'd start by inspecting the valve itself; the charge control solenoid turns off at the transition rpm.
I think if you have two mityvacs or whatever you could physically apply pressure to the two chambers at different rates to simulate what happens during transition.
I think if you have two mityvacs or whatever you could physically apply pressure to the two chambers at different rates to simulate what happens during transition.
Last edited by arghx; 11-12-09 at 09:35 AM. Reason: image
11-12-09, 02:12 PM
#10
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On a modified car what would be the benefit of having the primary boost low? If the car makes 10lbs by 3000 say you have another 1500RPM of wasted opportunity. Assuming the car can handle the boost why would it not be better to let the car go to 13lbs on the primary? I know that does not solve the under lying problem but who would want 10lbs when its safely capable of more. I am still too new so please excuse me if this was a dum question.
11-12-09, 02:50 PM
#11
It's only the fact that it should work and doesn't which means there is a problem somewhere. I'm not trying to boost specifically 10 pounds on the primary, its just that it should work. Anyway, maybe the the problem will worsen overtime and then be easier to find. The major issue where it would only boost 3 psi has been fixed and we're not taking off the plenum again to find this minor issue (unless you want to lol). Was just brainstorming now, more then anything.
thewird
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