Got the car on the road - running great except I can't boost above 5 psi. I rechecked all vacuum/boost lines and all are PERFECT. Car runs good in every other aspect except I am not getting the boost.

What could be the issue?

 

Boost leak at one of the silicone couplers. Intercooler maybe? Boost has to be leaking out somewhere.

 

Sounds like a leak. Could also be the gauge, how rich are you running?

 

I am holding 18 -22 in/HG vacuum, so I don't think it's the gauge. Would I still hold vacuum if it were a coupler? Also, I am holding 4 psi all the way to redline in 3rd and 4th gear - would I be able to hold boost if it were a coupler?

What are the chances a waste gate isn't opening?

In terms of A/F at WOT I am at about 10.1:1 - 10.4:1 so I am decently rich, but not richer than I expected to be.

I will check the couplers, keep the input coming.

 

Hi Zivman,

Great to hear that you're up and boosting!

Did you fit the restrictor (item 56) in http://www.************************/35...K_01-Boost.htm

This item is mandatory in order for the boost control mapping to function optimally.

George
APS Engineering

 

Yes, I fit that piece as per the diagram. One end is larger than the other, and the instructions do not state which direction it should face. The diagram appears to have the larger opening towards item 50 - SOLENOID - WASTEGATE CONTROL - After seeing the boost at only 4-5psi, I then changed the direction of the larger opening with no difference in boost levels.

I have rechecked all vacuum/boost lines connected to teh solenoid and all are kink/pinch free and ran correctly. I will recheck all the couplers tomorrow as it is nearing midnight for me and 5 am comes up pretty fast.

 

If all the connections are fine you must have a boost leak check all your couplers.

 

What exhaust are you running and have you dynoed the car to check boost versus power output?

 

I need to check the couplers today. No dyno yet, but the car definitely isn't pulling like it should. It has power, but not like an 8-9 psi monster putting out near 400 rwhp. If I had to guess at power, I would guess maybe 300-325 rwhp.

I am running resonated test pipes and greddy evo2 exhaust. My thought was that the unichip itself was keeping the boost so low????? It is probably the simplest thing, so it is probably a coupler

 

Thanks to Tuan and Irshad at GRD.

After an easy test, we have figured it to be the unichip or control solenoid for the wastegates. What I did was pinch the line that feeds the wastegates coming off the solenoid. At that point, I could boost to 7, 8, 9psi without issue. This confirms that the turbos are good, the wastegates are good, and that the actuator arms are not stuck or binding. Careful if you attempt this as the turbos will boost to there max and you need to watch your boost gauge in order to know when to let off the throttle.

For all of you that thought I had a leak somewhere, Tuan stated from the start that it wasn't likely a leak and that it was something with the wastegates.

 

So what now?

Mine seems to be losing boost.....on the first drive, I was hitting around 9psi and losing traction in 3rd, now I'm only hitting around 7-7 1/2 and not even screeching 3rd. I've listened for leaks around all the couplers and haven't noticed anything, but I need to have a second person rev the car for me while I listen.

 

great news...glad the problem was easily solved.

 

Sent GRD the solenoid and unichip for testing and replacement.

 

So if I pinch off that hose, I should be getting a full 12psi of boost assuming I have no leaks? Not that I'd try to hit 12, but just hypothetically?

 

Yes

 

Cool, keep us updated Zivman.

 

Do you notice your boost slowly dropping? Like you hit 9 at 4500 rpms and as you approach redline it falls off to 7.5? If so, it could be related to the actuators.

Do you hold good vacuum? 20 in/HG? If you had a leak, I doubt you would be able to hold those boost levels or keep good vacuum

 

Please post back once you find out for sure what the problem is.

Later,

 

No, the boost is holding just fine, it's just not peaking as high as it was the other day. It sits right on the red mark between 5 and 10, which I'm assuming is 7.5psi. The other day it was def at 9.

My vacuum at idle is a little over 20, at least 25 or close to it, so there are no vacuum leaks.

Oh, I trimmed the right oil drain and took out a tad of oil, and my smoking problem has greatly decreased, although every once and awhile I'll notice some when I come to a stop.

 

You might have spiked to 9. If we were running manual boost contollers with a spring, it could have been related to the weather. With MBC, you boost higher in cold weather. This might still be the case.