i'm getting low boost (3-4 psi) when the seconadaries are suppose to kick it. it's accompanied by a police siren sounding sound. i'm thinking somebody most have heard this sound before and can quickly tell me what the problem is.

the car was running fine this morning. on my way to the bay area's rx-7 dyno day i decided to turn up the boost on the PFC. just so happen to see a a new 911 turbo and wanted to see how bad i would get left behind. think the PFC wasn't that good at controlling boost, went up to 14psi instead of my desired 12psi. after that the car started make the siren sounding sound whenever i'm trying to give it throttle and let go quickly at higher rpms.

thanks

 

How many miles are on your turbos?
I have hearda turbo car make a similarly described sound when a compressor turbine is rubbing the housing. in other words *turbo rebuild/replace*

-Kib

 

heard the same on my primaries...
yep time for new turbos

 

In the supra world it is called the "death whine"...

 

d'oh!!!!

turbos have 107k miles on them. damn, i was hoping it would be something stupid like a hose or solenoid, but new turbos...damn, the 911 turbo literally fucked me up!!!!

 

How many miles are on your turbos?
I have hearda turbo car make a similarly described sound when a compressor turbine is rubbing the housing. in other words *turbo rebuild/replace*

-Kib

 

computer glitch? or are you experiencing some time warp :p

 

hes caught in the matrix.

 

it could be the one remaining rubber boost hose too, check it yo

mike

 

you turning ebonics on me mike?

 

i thought it was an east bay thing?

mike

 

I had a similar problem and it turned out to be a broken check valve.

 

im telling you tinou, check the turbo control actuator, the physical actuator with the sliding vacuum activated rod and butterfly type door, not just the solenoids and check valves. i would really recommend starting with that.

 

Stupid server timed out...
hence the duplicate and late post

-Kib

 

if anybody cares....it turned out to be a faulty solenoid.

 

I care! thanks!

 

Glad you posted the outcome and fix.

 

ttb, were the solenoids, the turbo control solenoids, just underneath the extension manifold (UIM)? How how hard were those solenoids to replace? I'm having some issues with my secondary turbo control, like you did. I'm hearing a whistling sound between 3000 and 4500 rpm, right when the secondary turbo is supposed to be spooling.

There are two solenoids that control the turbo control actuator--one solenoid applies pressure, the other applies vacuum. Both are needed for the turbo control actuator to work properly.

My J-spec twins are 5200-miles new, so I can't believe my turbo control actuator is bad. I did replace the 1-way vacuum chamber check valve to no avail. A disconnected vacuum line beween the turbo control actuator and the vacuum line tray might also affect the function.

Did you try getting out of the gas, and then reapplying the gas to get the secondary turbo online? This is the classic symptom of a vacuum leak or turbo control solenoid/actuator problem?

Getting off and then back on the gas is what I must do to get the 2nd turbo to come online...a PITA, when trying to race a 911 twin turbo, you know LOL

I plan on replacing the turbo control soleniods, a couple of more check valves (vacuum line, double throttle control, and pressure chamber), and checking the vacuum line between turbo control actuator and rat's nest this week.

Hopefully I'll be back on the road killing 911 twin turbos like you are

 

wished i could be more helpful, but i'm one of those guys that don't work on their cars :-(

forgot all the details my mechanic told me...from what i remember it was because my solenoid was faulty. he said something like he measured the resistance/voltage and it was too high (?), and the ECU didn't pick it up because I have a power FC. so he replaced it with a used solenoid. and now i'm boosting fine again.

and yea, my problem was kinda on and off..sometimes i was able to get it to boost fine, other times it wouldn't.

i'll probably see him within the week to pay him, so I'll ask him exactly which solenoid was bad and let you know.

tinou