So my car's been running on low boost lately... something like .6 bar, transition spike @.8 bar, and back to .6 bar by 4500 rpm. Checked for the obvioius leaks... all intercooler piping (have efini Y pipe... so that particular connection is no longer a worry), checked 1" hoses around BOV and CRV... to no avail. THEN I check the pressure chamber... and this is what I find... check out the attachment...



Has this happened to any of you before?

 

Well, I replaced the check valve and take it for a spin... boost still at .6 bar max... =( I guess I'll have to start looking for other leaks.

 

Hey Rikki... I don't think I put it in wrong... I put it in the same way the other one was before... and it also has an arrow on it... assuming the arrow shows the direction for flow (y pipe to pressure chamber, being the black side connected to the y-pipe and green side connected to the pressure chamber).

As for the check valve... just picked one up for $27... frick'n steep for a little plastic valve! Thanks for your post!

Brian

 

As for boost problems.

1. Check valve
2. Vacuume hose
3. Boost solenoid valve
4. Knock sensor
5. ECU itself

You tried 1. & 2.
Replacing 3 or 4 is very expensive
Try disconnecting knock sensor.

 

if the knock sensor was sensing knock and not allowing boost,etc... woudln't disconnecting it cause my engine to detonate... which means... bye bye apex seal? Just wondering... thanks for your help!

 

MILD7:

I have this same problem. When it is cold it works fine but when it gets hot I get 8-6-8 pattern.

I tried swapping my ecu and plugging the egr and can't figure it out

 

bump

 

as long as the sequetial turbos work low boost is either caused by a leak, or a restriction. or it could be the wrong boost pills, a broken boost solenoid.

mike

 

I really sounds like a turbo control problem. And it surely has nothing to do with your knock sensor.

If there was a leak in the intake piping, you would either see no boost (pipe completely disconnected) or the boost would be low but would increase slightly throughout the rpm range (split coupler or bad gasket). You would also hear a loud "whooosh" noise from up front when you are driving under boost.

Are you sure the pressure hoses going to the wastegate actuator and precontrol actuator have the stock pills in them? What did you change when this problem started to occur? I think something is making your wastegate stay open too much, like a bad solenoid or no/wrong pill.

I would not consider replacing your ecu until you have exhausted all other options first. I have never seen that be the problem. I am not saying that it doesn't happen, but it is very rare.

Good luck,

Jeff

 

Thanks for your responses... was wondering if getting/making a manual boost control would be a good fix (assuming low boost is caused by the wastegate/actuator). Might go that route and see what happens.

 

.67 bar CORRECT and .8 being kinda HIGH??

 

.6 bar is roughly 8 lbs of boost... I believe stock to be 10-11lbs. I use to boost .8 bar, awhile ago. .8 bar is about 11 lbs. I don't think .8 bar should be too dangerous. Correct me if I'm wrong on this.

 

O.K.

My car started this 8-6-8 **** after I installed my FMIC, DP, High flow cat, and PMS. I did everything at once. When the car is cold I can get 10-8-10 but once it gets hot I get 8-6-8.

Ive pulled the Vac chamber(?)(the one above the alternator. I found one of the hoses underneath popped off so I hooked it back up looked around underneath the manifold and didn't see anything wrong. I put it back together and it worked. 13psi!
Then I blew a intercooler coupling. Ive replaced all my intercooler couplings. Ive disconnected my EGR. And I can't get it to work anymore. I tried pulling the vac chamber again but nothing worked. I can't figure mine out.

I'm gonna try the poor non seq. conversion and see what happens then. Hopefully that will work.

 

And I even tried swapping my stock ecu for another stock ecu that had no boost problems. That didn't work either.

 

Man..Mild7...I had those check valves...I would of gave you mine for Free...or for some sausage links!!! Make sure the check valve is pointing in the direction going into the manifold...or else just get all of your vacuum hoses done to silicone...that cured all of my boost problems....R & R in Upland did mine for about $250!! While they were doing that they found some clogged up soleniosd...the ones under the manifold!! Get that **** done fool!