Poor secondary boost
04-09-08, 09:02 PM
#1
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Poor secondary boost
I just got off the phone with my mechanic. He was doing several things for me on the FD and I'd also asked him to chase down the reason for the poor boost past transition. I'm only getting 5-6 psi.
He found a number of little things that he was able to fix and some that he wasn't but he wasn't able to find the root cause of the poor secondary boost. Since I want to drive the car in some autocross events, and the car is performing well at lower rpm, we decided to hold for now and maybe address it later.
One thing he found was that the pressure chamber wasn't holding a charge for long. He said it wasn't that it was leaking, so much as the system was using the pressure early and completely. Frankly, this doesn't mean a whole lot to me as I don't really understand the system.
He went through the rats nest and found/fixed a few things there, but they weren't the cause of the low secondary. He said he could keep plugging away at it to see if he could find a problem even to the point of pulling the turbos apart, but he is sensitive about spending my money (which I appreciate).
Anyone have some ideas on the pressure chamber or some not-so-obvious ideas on the boost? I know it is a long shot since this guy really does know his rotaries. I'm going to assume that all the more obvious things he already checked out.
He found a number of little things that he was able to fix and some that he wasn't but he wasn't able to find the root cause of the poor secondary boost. Since I want to drive the car in some autocross events, and the car is performing well at lower rpm, we decided to hold for now and maybe address it later.
One thing he found was that the pressure chamber wasn't holding a charge for long. He said it wasn't that it was leaking, so much as the system was using the pressure early and completely. Frankly, this doesn't mean a whole lot to me as I don't really understand the system.
He went through the rats nest and found/fixed a few things there, but they weren't the cause of the low secondary. He said he could keep plugging away at it to see if he could find a problem even to the point of pulling the turbos apart, but he is sensitive about spending my money (which I appreciate).
Anyone have some ideas on the pressure chamber or some not-so-obvious ideas on the boost? I know it is a long shot since this guy really does know his rotaries. I'm going to assume that all the more obvious things he already checked out.
04-09-08, 09:42 PM
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As far as I know, the pressure chamber is fairly simple. Boost through the check valve, into the chamber, out to the secondary control solenoid, and out to the secondary control actuator. Gotta narrow it down to leaking vacuum lines, leaking check valve, cracked solenoid, or the worst case of a faulty actuator.
04-11-08, 05:19 AM
#3
The pressure chamber has two lines:
1) to the check valve
2) to the turbo control pressure solenoid.
If the pressure chamber holds pressure during idle, these branches are probably fine.
When the secondary is in operation, the tc pressure solenoid is open and extends to the turbo control actuator. Your mechanic said it loses pressure during secondary boost only, so look for the leak in these lines or the actuator itself.
Dave
1) to the check valve
2) to the turbo control pressure solenoid.
If the pressure chamber holds pressure during idle, these branches are probably fine.
When the secondary is in operation, the tc pressure solenoid is open and extends to the turbo control actuator. Your mechanic said it loses pressure during secondary boost only, so look for the leak in these lines or the actuator itself.
Dave
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