Boost questions. Help

[josh38127]

I was prefroming a BLT today. I noticed that the hose from the valve cover leaks all the air out before I can make boost presure. But when I plug it with my finger tip pressure builds and blows out of a valve cover bolt hole.

what the hell si going on. How do I fix it.

Update; When I crank and run the car. The boost gauge pulls VACUM.Is that normal.

 

[gofer]

i pulled the below info from a site i used the first time i did a BLT. read it ALL over and over until you understand it.
yes your boost gauge should read vacuum at idle, about 18 - 20 inches of mercury.



Test the whole intake by connecting the tester directly to the turbo
This is not the best choice because turbo seals can leak when the car is not running. It can also be difficult to track down large leaks this way. It just tests too much at once. Once you have fixed most of the leaks, then it is not a bad way to quickly test for new leaks. Just keep in mind that a bubbling oil sound in the oil pan is usually just air slipping past the turbo seal. Bypass the turbo and re-test.

Connect the tester to the intercooler inlet (or the lower intercooler piping if you have hard piping.) Then put a plastic plumbing cap in the end of your upper intercooler piping coupler.
This is the best way to test the first half of your intake. You can move the cap further downstream if you want to test your intake in even smaller portions.

Connect the tester to the throttle body. Pump it up and check for leaks at the throttle body shaft seals, throttle body gaskets, intake manifold gasket, fuel injector seals, and intake valves/valve seals.
Most people will be suprised at the number of leaks this test will find. Have fun. Clamp off the PCV line if you suspect it is leaking and continue testing. Some people find that their boost gauge line and even the gauge itself is leaking. Don't forget to check inside the car during this test.

 

[LiquidX]

Is your PVC valve bad? That valve is what prevents boost from leaking into the crankcase/head. Also, it sounds about time for you to replace your valve cover gasket.
Valve cover gasket need just one.
Spark plug well gasket need 4 of these.
Half moon seal need just one.

Or just get this kit from ExtremePSI
Valve cover gasket kit

Every car will naturally be in a vacuum until the amount of air entering is greater than the vacuum pull of the motor I.E. forced induction. You won't enter positive pressure until you build enough positive airflow by spinning the turbo.

 

[josh38127]

Thank gofer Im test my intake tommarow. Could the reason my car is running so crappy because of boost leaks.

 

[LiquidX]

Thank gofer Im test my intake tommarow. Could the reason my car is running so crappy because of boost leaks.

Yes, boost leaks kill your performace. The stock MAS reads how much air is coming into the system and tells the ECU how much fuel to spray. When you have a boost leak, metered air leaves the system so the air to fuel ratio is off. Also, your turbo will work harder to achieve the same power levels.

If a leak is bad enough your car can stall out, feel like there is no power when you press the gas, stutter down the road etc. Fix all leaks testing with a spray bottle of soap and water. Common places are throttle body shaft seals, injector seals, IM gasket, old vac. lines, leaking couplers.

How do I make/buy/use/troubleshoot a boost leak tester Don't forget to test to at least 20psi or higher.

 

[josh38127]

I just reinstalled my trottlebody new ISC,TPS,and shaft seals. During my BLT I didnt hear any leaks from it. If I run long enough the spark plug gally with fill with oil. Is that area soppose to have presser.

 

[LiquidX]

Use a spray bottle of soap and water as most of them you can't hear unless they are very bad. No, you have a bad PVC valve. What PSI are you pressurizing to and how fast is it leaking out? You should be able to hold at least 20psi for a minute.

 

[josh38127]

Use a spray bottle of soap and water as most of them you can't hear unless they are very bad. No, you have a bad PVC valve. What PSI are you pressurizing to and how fast is it leaking out? You should be able to hold at least 20psi for a minute.

I pressurize at 20lbs. Soon as I remove the air commpressor its dropps in a matter of secs. Its coming out of the nipple on the valve cover. Not the PVC. Its the one next to CAS.Got a new PVC

 

[tunethis]

I pressurize at 20lbs. Soon as I remove the air commpressor its dropps in a matter of secs. Its coming out of the nipple on the valve cover. Not the PVC. Its the one next to CAS.Got a new PVC

You may have a leaking pcv valve. Air isn't supposed rush out of the valve cover like that. The pcv valve is supposed to keep boost from entering the valve cover. Test it by un-screwing it from the valve cover but, re-connect the hose and keep it connected to the intake manifold. Pressurize the system like before and listen. If the pcv valve is leaking, you'll hear it. You can place your finger over the end of it to verify.

Only replace your valve with a factory Mitsubishi one. It is designed to hold boost unlike the cheap auto store versions. Most of them leak right out of the package. If your valve cover is still leaking without the pcv valve screwed in, you may have internal issues.

 

[josh38127]

You may have a leaking pcv valve. Air isn't supposed rush out of the valve cover like that. The pcv valve is supposed to keep boost from entering the valve cover. Test it by un-screwing it from the valve cover but, re-connect the hose and keep it connected to the intake manifold. Pressurize the system like before and listen. If the pcv valve is leaking, you'll hear it. You can place your finger over the end of it to verify.

Only replace your valve with a factory Mitsubishi one. It is designed to hold boost unlike the cheap auto store versions. Most of them leak right out of the package. If your valve cover is still leaking without the pcv valve screwed in, you may have internal issues.

Its not leaking from the PVC. Its leaks from the nipple just above the CAS.

 

[habitatguy187]

Its not leaking from the PVC. Its leaks from the nipple just above the CAS.

What he's saying is that the if the pcv valve is leaking it will pressurize the crankcase and valve cover area and push air out the breather tube. The pcv valve is above cylinder #4 and has a decent sized vacuum hose running from it to your intake manifold. Just check out those links provided above by Liquid and you'll figure it out.

 

[LiquidX]

Its not leaking from the PVC. Its leaks from the nipple just above the CAS.

The PVC valve on the car is to prevent positive air pressure from entering the crankcase while allowing a vacuum to pull out fumes. A bad PVC will leak positive pressure resuliting in air rushing out of the breather nipple and from the oil cap.

If you want to verify, block off the vacuum hose that leads to the PVC valve, if air stops rushing out then your PVC valve is in fact bad and not holding boost. If it persists then you have bad valve seals.

You have to check any PVC valve you purchace wether it is from Mitsubishi or from an auto parts store. Each version can leak. If you can blow into it and have air exit the valve it will not hold boost. I went through 7 OEM valves to find one that didn't leak.

A way you can stop the leak is buy utilizing a check valve before the PVC. I run one and don't have problems. PVC doesn't leak either.
Check Valves | U.S. Plastic Corp.

 

[josh38127]

Thanks Scott. I read the thread again I get it now. I do the last check you said. I try a check valve too.

 

[400whptsi]

im having problems to the car takes off great in first gear the in second it fells like it doesnt wanna go then the boost goes to 18 and i hit fuel shut off what can i do to fix it i unhooked the bov and it runs fine but only puts out 7-8psi and its set for 11.06psi the bov isnt ajustable is the bov bad? and why am i getting boost creep the motor is completely redone from top to bottom so it has all new gaskets