Im new at this whole turbo thing..need to see if anyone can help me

[clipse-gst]

I just bought this 97 eclipse gst,its my 1st turbo i have ever own so i don't know a lot. I was just wondering if anyone could help me. When i got the car it ran at 15 psi every time it spooled up,never went over. Now it spools up anywhere from 15-20 psi, and now when it hits 20 psi its like it cuts out and then instantaneously drives normal again. can anyone tell me why its spooling up so high now and why is it cutting out around 20 psi

 

[GofaST4life]

im assuimg there is an after market boost meter, make sure it was hooked up properly...and buy a MCB (manual boost controller)...

 

[BigSorn]

Do you have aftermarket exhuast?

I've herd that can cause boostcreep.


also, do you have a MBC?

 

[nfernotalon]

Have you done anything to the car? Do you have a manual boost controller? Youre hitting fuel cut because of the more boost youre running.. thats dangerous without the proper fuel upgrades.

 

[BigSorn]

Also, why it's cutting out at 20 psi is your ###### hitting fuel cut, the stock fuel system is only good for about 16psi.

 

[clipse-gst]

no i dont have a mbc yet...yes i do have a aftermarker boost guage....it has 160,000 miles on it

 

[TrAb]

Please dont go around boosting until you get this problem figured out, you will be knocking the motor to death...

 

[clipse-gst]

dont worry i have been babyin it since it happened....i just wanna fix it asap

 

[TSITuner4Lyfe69]

Do you have any exhaust leaks(by the down pipe) if so your getting boost creep if no leaks then check the vacuum lines coming off the waste gate they might be unhook if so just hook the vacuum line directly off your wastegate your j pipe theres a little spot to hook it up and then you should be running stock boost

 

[kenamond]

The boost control system on a stock car is as follows:

Boost pressure is produced at the outlet of the turbo compressor. There is a nipple there to tap into this boost pressure so that it can be controlled.

The vaccuum line on that compressor outlet nipple is connected to a T fitting. One of the other lines off the T fitting goes to the wastegate actuator (WGA) (bronze colored thing bolted to the compressor housing).

The other line on the T fitting goes to a boost control solenoid, but I'll cover that in a bit.

The WGA has a diaphragm inside. The diaphragm is connected to a rod called the actuator arm that goes out the back of the WGA toward the turbine housing on the other end of the turbocharger. Inside the WGA is a spring that holds that arm inside the WGA. If the pressure signal at the WGA nipple gets big enough, the diaphragm pushes the spring and the arm moves out of the WGA (extends).

The WGA actuator arm connects to the end of a small lever on the turbine housing.

The lever turns an internal valve inside the turbine housing called the wastegate (WG).

The WG is a door that, when opened, lets high-pressure exhaust bypass the turbine wheel (if the WG is open, some of the exhaust can take a shortcut and not run through the turbine wheel).

The turbine wheel, when powered by high pressure exhaust, drives the compressor wheel on the other end of the same shaft. The more flow through the turbine wheel, the harder it drives the compressor wheel, and the harder the compressor works to compress the intake air (boost).

So we've come full circle. The compressor pressurizes the air, the nipple on the housing sends a pressure signal to the WGA. The WGA will move the actuator arm when the boost pressure signal reaches a certain level (around 9psi). Then the actuator arm extends and turns the lever on the turbine housing which opens the WG inside. That lets some exhaust bypass the turbine wheel. That limits how hard the turbine wheel is being driven. That limits how hard the compressor wheel is working to generate boost.

So...our cars run higher boost than 9psi which is what makes the WGA actuator arm move. Why's that you ask? Well, we get back to that 3rd nipple on the T fitting I mentioned way back when you were still awake. The stock boost controller bleeds off a bit of the air at that third nipple on the T fitting. In doing this, the pressure drops as it goes from the compressor nipple to the WGA. So the WGA sees less pressure than the compressor is producing. So the compressor has to boost a bit higher before the WGA reaches its actuation pressure.

Also, the stock boost control solenoid (BCS) has a solenoid (hence its name) that the engine computer (ECU) can close if it thinks the engine is running too hard or having other problems. When it closes the solenoid, the air leak is blocked, and all of the sudden the WGA sees the actual boost pressure, so your boost drops back down to 9psi. If the ECU thinks things are good again, it opens the BCS solenoid again, and your boost rises back to around 11-12psi.

Ball-spring MBCs are different, but I'm done typing, and the installation of them is covered more times than bleeders, so you can search. If you understood what I said about the boost control system of our turbochargers, you'll probably find it a lot easier to understand how a ball-spring or other type of MBC works.

 

[clipse-gst]

thenx alot ..you explain everything for me...i just ordered a mbc and i should get it sometime next week...thenx alot everyone,you have been alot of help