Higher boost after tb shaft seals

[93RS]

Hey guys I just did my tb shaft seals..... Along with a thermostat, valve cover gasket, upper radiator hose, oil change and coolant change..... Also regapped the plugs to .028. The only "mod" done to it is the bcs restrictor removed. Anyway when I was doing the shaft seals I stripped the butterfly screws so replaced with smaller bolts... So after I got her all put bak together I did a BLT and I can't find any external leaks but it sounds like its flowing into the intake and therefore not holding pressure.... I took it out for a drive, it idle surges and it allthe sudden its pushes 14psi of boost I'm not sure if to be excited or scared.... I guess in thinking about it it seems to go to like 15 lbs then down to 14.... HELP!!!!

 

[HIGHPSI4]

You were losing boost pressure around the leaking seals.

 

[93RS]

But I was only at 10 psi b4.... A full 4 psi??? And can just the bcs removed get these results???

 

[Budget90GST]

Why don't you try re installing the BCS restrictor back to see where the boost ends up?

You can always remove it again after, and it's simple enough to do.

 

[steve]

You say your only mod if the BCS restrictor, does that mean your using the factory boost gauge for these numbers?

 

[93RS]

No it has a boost gauge, although I wouldn't consider that a mod.... And I no longer have the restrictor. And correction it goes up to like 13 or 14 then goes down to 12 13.... The boost going higher then lower is what scares me.

 

[lil corb]

Sounds like it's just hitting boost spike (dramatic increase of boost then settling down to target psi). Mostly likely the boost leak is causing this.

Understaing more about boost spike

 

[93RS]

Any ideas on the boost leak itself... I can hear it leaking but like i said it sounds like its flowing into the intake manifold and disipating... I can clearly hear it and its not leaking externally anywhere i can see.... would a mbc help this issue??? I have one just not installed, wanted to fix the shaft seals first.

 

[steve]

When you pressure test, you're going to fill the manifold and cylinders. If you haven't turned the crank to a spot where no more than one set of valves per cylinder are open the pressure in the intake is never going to build.

Remember even with the throttle closed the engine idles so air should pass into the intake. You just don't want it to go out the exhaust too. If you set the crank to about 30* ATDC at least one set of valves in each cylinder is closed so air can't leak out that way.

 

[93RS]

When you pressure test, you're going to fill the manifold and cylinders. If you haven't turned the crank to a spot where no more than one set of valves per cylinder are open the pressure in the intake is never going to build.

Remember even with the throttle closed the engine idles so air should pass into the intake. You just don't want it to go out the exhaust too. If you set the crank to about 30* ATDC at least one set of valves in each cylinder is closed so air can't leak out that way.

That sir is some awesome info.... my question is how do I do that????

 

[steve]

Look at the timing marks on the front cover and pulley, note how far it is (distance along the outer edge of the pulley) from the T to the 20* BTDC mark. Turn the the crank to TDC and then continue 1.5 times as far past TDC rotating clockwise. It doesn't have to be exact just in the ball park.

 

[93RS]

Could I get some pictures that kind of confused me.... is driving and/or boosting going to hurt the car? And would a mbc stop the spiking?

 

[steve]

Sorry I don't have any pictures handy. I forget how long the little timing marks on the front cover are but lets say they are 1 inch long. What I'm explaining is that you want to turn the crank so the the timing mark in the pulley is 1.5" clockwise from the TDC mark on the front cover and then go do your pressure test.

 

[93RS]

Gotchya, I'm assuming that ill have to break out a breaker bar to rotate the motor. Is the mbc gonna stop my spiking? I planned on setting it to 14 psi if that won't hurt anything....

 

[H@xtGSX]

The mbc won't stop the spiking if it is related to a boost leak. It is just controlling when the wastegate opens up. Just keep plugging along finding and fixing those boost leaks. I've been chasing them for a couple weeks, and it makes a HUGE difference in how the car behaves once they are fixed. I did the throttle body o rings this weekend, double clamped all my IC connections, replaced and re-plumbed all of my vacuum lines for best response, zip tied every one of the vacuum line connections, replaced the gasket on the blow off, rtv'd the gasket on each side of the throttle, and replaced the PCV hose. The only one that is still possibly leaking a tiny bit is the brake booster line. It idles glass smooth now, the boost builds much faster, lower, and smoother (mine was spiking pretty bad also), and in general acts much better. I was pretty amazed at just how much performance is lost with even a little leak.

Don't forget to check your boost gauge and mbc lines for leaks too. I found out that my gauge was leaking some at the compression fitting because the little metal insert was cutting into the line.

One last little tip I found useful is 3M spray adhesive. I used it at each of the IC clamp spots, spraying a thin coating on then putting the connection together and clamping down on it. If you've ever had a connection blow apart under higher psi, you know it sucks and is a pretty rough ride that kills the motor. That spray adhesive is just strong enough to hang on to those couplings well at higher pressure, but not make it impossible to remove later.

 

[93RS]

Well ill do a proper BLT sometime soon.... Is jumping up 1 psi then coming down really considered spiking???? Other then idleing a little high and the minute amount of idle surge I'm seeing it runs a million times better.

 

[H@xtGSX]

Sounds like a leak that is pretty sealed until you hit that pressure, then it opens and you lose psi. It's not uncommon. Easiest way to diagnose the intake piping and intercooler is to block the pipe off at the throttle body elbow and pressurize from the pipe directly attached to the turbo discharge. Otherwise, you lose pressure through the turbo seal into the oil pan and through the valves and rings.

 

[93RS]

I will get that BLT done and while I got the intake pipe out ill install the MBC.... Will 14 psi hurt anything????

 

[H@xtGSX]

It shouldn't. That's the pressure the 14b is designed for, and it can handle more. The motor can take it too. Just try not to go over 15 psi on the stock fuel system or it may go lean. Not a certain thing, it mainly is dependant on the level of maintenance the car is at.

 

[LiquidX]

I recommend testing at least 10psi over what you are running.

If you want a sure way to have all the intake valves closed, pop the rockers off before testing.

 

[93RS]

On my way home from work the laser bucked going into boost, now it will only hit10 psi like before but now the idle surge is a lot occuring more. I'm starting to get scared

 

[H@xtGSX]

Sounds like more boost leaking.... That's how boost leaks tend to manifest. Nothing to be scared about, you just need to get in there and find what is loose, leaking, or cracked.

 

[TSi Kid]

Your car is possessed. What you need to do is a "possession test".

Go to this site and purchase the tester Boostpro.net : Products - Boost Leak Testers

Then what you'll do is connected it to the intercooler piping coming off the J-pipe of your turbo. From there, run pressurized air through your system and listen for a "pshhhhh" noise.

That is the ghost.

From there, tighten the piping so that the noise goes away. And there you've done it! You've vanquished the demon, and gotten rid of your problem.

 

[LiquidX]

Don't use the boost pro tester. I'm not a fan of their design at all. After 20psi the tester will begin to pop out of the coupler due to no seating grooves unless they redid their design.

I recommend the www.siliconeintakes.com leak tester.

 

[H@xtGSX]

I use the $5 Home Depot ghetto leak tester and can put 30 psi down my car's throat without a problem.

Actually.... I just re-read your first post. How much smaller bolts ( I assume you used a bolt instead to hold the throttle plate) did you use? If your throttle plate is loose in there it could be sticking open, then flopping shut, or fluttering around some causing weird symptoms. At this point, I think you should remove the throttle body again, peek at your O-rings to make sure they didn't get pinched, and look very carefully at the throttle plate. That thing is under some serious force when you're running boost, and if it's loose even a little, you will have some weird problems from it not seating right. If you stripped the screws, it is better to tap it out 1 size larger so it is TIGHT.

You may not be dealing with a boost leak at all, but rather a loose throttle plate.