If the car has always run this boost then you are probably missing the pill in the vacuum line on the compressor. If the car just started doing this recently and you have a CEL then you need to pull the code. The car/ECU is unhappy and has the ability to run wastegate pressure to save the motor. If no CEL then it could be the solenoid,boost leak or preturbo exhaust leak.

 

when i first bought the car it had no pill, then i took it to super rupair and they put one in for me. Before the pill i was hitting 14 psi, now i only get 7.25 psi. I also have no CEL's. And i did a boost leak test last night and coudnt find any, how do i know if its a boost solenoid or a preturbo exhaust leak?

 

when i first bought the car it had no pill, then i took it to super rupair and they put one in for me. Before the pill i was hitting 14 psi, now i only get 7.25 psi.

So are you saying once you put the pill in the boost went down? Did you buy the car modded? List every single performance mod. If you bought the car modded and don't know what exactly has been done to it then it's going to be hard to help you.

 

i have exaust leak before the turbo where the o2 censor goest

and i have just 5psi and idont have any vacuum leak so is posible that causinme the problem because when my turbo boost start workin the car start to feel like loose the power and dont go any faster can some one helpme aneed to fix da and i dont have any other clue of whats going on

 

and i have just 5psi and idont have any vacuum leak so is posible that causinme the problem because when my turbo boost start workin the car start to feel like loose the power and dont go any faster can some one helpme aneed to fix da and i dont have any other clue of whats going on

:confused1:confused1:confused1. Engrish.......

 

Agree with donkey! But thanks for searching. Yes if you have a pre-turbo leak you won't get full boost. Get that fixed, pre-turbo leaks are bad

 

Someone else with the same problem has posted a thread.

It seems to me that the wastegate solenoid controller(stock boost controller) is at fault. My car has been doing the same thing 7 psi at max boost. I have changed all my vacuum hoses and i checked for the pill which was in the car. I even tried spraying some lubricant in the wastegate just in case the spring was stuck. It seems to me that my wastegate controller is at fault but i have no clue on how to test it( can we just use a DMM and test for continuity?). My presumption is that this part is giving out. If you find something out let me know.

-Sal

 

It's a 12volt unit and can be tested by either placing the car in diagnostic mode or attaching test leads to the solenoid and energizing it straight from the battery. You should here it clicking/actuating.

 

testing Wastegate solenoid valve

Could i just disconnect the vacuum hose that flows to the wastegate and turn the car on? if there is no air passing by does that mean the wastegate solenoid valve is closed and therefore not working? if air is passing by at idle then maybe i could rev the car and see if the controller closes early(knock sensor)?

Does this sound like a viable way to test the wastegate solenoid valve(controller)?

-sal:confused1

 

The air is coming from the wastegate line so disconnecting it would not help you diagnosis the problem. The solenoid is normally closed. It is set up to bleed off air by the ECU using a varying duty cycle that is done by rpm vs throttle position. What does the knock sensor have to do with this? Not sure what was wrong with the ways I suggested......

 

You are right there is nothing wrong with what you had suggested. I had an idea that would keep me from doing any electrical work. I was also mentioning the knock sensor because i read on different site that if the engine is knocking the solenoid valve will bleed off the air earlier to protect the engine.

Either way i just bypassed the solenoid valve to see if the car would boost past .05 Mpa and it did so i have now narrowed down the problem.

 

Just kind of an update on Yamaha's situation... just in case someone else searches and finds this and has the same problem. (7psi boost, and no check engine light)

If you purchased the car and are unsure of the modification history of the car... before you pay someone to fix it, pull the tune. If a person had previously had a Manual Boost Controller installed, or an aftermarket electronic boost controller (not a boost control solenoid) then the Wastegate Duty Cycle will have been set to 0. This was the case in Yamaha's situation. A simple tune fixed his problem.

 

Sinister is correct! Damn people who can retune their cars before selling it, just to screw the next person over.

 

crappers

K so i got the used stock wastegate solenoid valve and the car still did not boost past .05 Mpa approx 7 psi. Is there a fuse that connects to the wastegate solenoid valve?? im gonna test it tomorrow to see if its giving off the 12volts by connecting a multimeter to the wastegate plug.

Anyone have any experience with this problem?

 

You have the pill in the correct vacuum line?

 

Correct I do have the pill in the car and there is no vacuum leak.

I have narowed it down but im not to keen on how the 12V is applied to the Wastegate solenoid valve. The valve works, i tested it using a 12V battery and i actually heard it open the valve and when i removed the voltage it closed again.

I went ahead and tested the connector and found that there was power on the + side but the ground was non-existent. Im not sure if the ECU has a switch that enables or disables the ground. Either way my ground is not working. If anyone knows anything about this please let me know. Im going to look through the mess of wires and see if it has been compromised( cut, pierced) other than that im really not sure what to do.....

on top of that my alternator just started whining so it looks like i need to replace the alternator too.... sigh....

 

The ECU controls the ground. At idle the solenoid is not energized. Generally the ECU on the stock ROM will not energize the BCS until the engine rpms are over 2000 and the throttle postion is at or greater than 24%. The pill also has to be in the line that goes in between the compressor nipple and the vacuum T.

 

Do you have the correct pill? I know it may sound dumb, but the pill sizes are different for the different years.

Are you sure you are not running wastegate pressure, wrong tune on the ecu?

 

It must be the correct pill because it was working before then one day i just lost half my turbo boost.

K with the new info i can see that everything seems fine and this narrows my search down to the negative wire(on the wastegate solenoid valve), im not sure how i can check the ECU so i will be looking for a broken wire that leads to the ECU.

or

Possibly the mechanism that sends the rpm signal and the throttle position maybe. Does this mechanism use a fuse?

thanks for all the help so far guys! I am close to figuring this out and i am definitely learning a ton about the WRX.

 

Possibly the mechanism that sends the rpm signal and the throttle position maybe. Does this mechanism use a fuse?

thanks for all the help so far guys! I am close to figuring this out and i am definitely learning a ton about the WRX.

If you did not have an rpm signal or throttle position your car would have DTC's for this,your tachometer would not work and your car would not run. No fuses as they are both 5v sensors that are powered by the ECU. Have you not tried putting the car in diagnostic mode like I suggested earlier? The ECU should cycle the BCS.

 

Well Mr. Donkey,

It seems like putting my car in diagnostic fixed my problem. Thank you for your suggestion.

Why does this happen?

 

Sorry for bringing this back up, but I'm starting to have similar issues with my08 XT... It won't boost past 6psi with no leaks pre or post turbo.. I ran the diagnostic and no CEL come up and the solenoid is clicking... My odometer is at 58k and the only addition I have are a green drop in filter and a boost gauge... Salica I know you swapped out the solenoid might mine still be bad although it still clicks under diagnostic? At 6psi my boost drops and my rpms jump up and it feels like I losing power and not holding boost...