Boost Leaks!

[RiceKiller_TSi]

Got some, need to make a detector...
I didn't find the info at vfaq.


GOT LINK?

 

[oldman]

Good deal, sounds like you lucked out there, at least you know you're boost leak free now. On a side note, what part of the divider broke off? Those are crucial in redirecting exhaust flow?

 

[RiceKiller_TSi]

Good deal, sounds like you lucked out there, at least you know you're boost leak free now. On a side note, what part of the divider broke off? Those are crucial in redirecting exhaust flow?

Its that little center divider part (first and second pics) that people usually get rid of when porting http://www.vfaq.com/mods/porting-exhman.html so I don't think I'll miss it that much!

I sooo glad I found those boost leaks though because my turbo lag was very bad before this happened and I probably would never have been the wiser. When I put the car back together tonight and drive it I'm sure that the throttle response will be better than ever.

 

[RiceKiller_TSi]

Promised pics. Everybody loves pics.

 

[oldman]

Wow, looks like there is nothing left in the collector unless it's too dark to see in the pic. If this is the case, I recommend getting another manifold.

 

[RiceKiller_TSi]

Wow, looks like there is nothing left in the collector unless it's too dark to see in the pic. If this is the case, I recommend getting another manifold.

Well, the divider is gone now but thats about it. I've driven the car today and it pulls pretty good minus a few boost leaks that I havent fixed yet.

Whats wrong with the manifold without the divider? I was actually gonna get that ring ported out of there as well and gasket match it.

 

[RiceKiller_TSi]

Hey this question is posed to anybody that wants to take a stab at it of course... but, what is usually going on when you do the boost leak test and you can hear the air escaping when you take off the oil filler cap?

It leaks out into the engine. I thought it was supposed to stop at the throttle plate.

 

[oldman]

but, what is usually going on when you do the boost leak test and you can hear the air escaping when you take off the oil filler cap?

Turbo seal, pcv valve, valve seals and piston ring.

It leaks out into the engine. I thought it was supposed to stop at the throttle plate.

If this were true, your car will not run at idle. The throttle plate is never truly closed, air will flow around the gap of the plate, FIAV, BISS...etc. During a intake pressure test, pressure will get all the way up to the intake ports of the head including at least one combustion chamber as at least one set of intake valves will be open.

 

[RiceKiller_TSi]

If this were true, your car will not run at idle. The throttle plate is never truly closed, air will flow around the gap of the plate, FIAV, BISS...etc. During a intake pressure test, pressure will get all the way up to the intake ports of the head including at least one combustion chamber as at least one set of intake valves will be open.

Ok, thats what I thought to begin with, so since that is true, then hearing the air escaping into the head is normal then... right?

Side note:
I've got my boost back but I have been unable to get it to hold it for 30 seconds before leaking out. My FIAV is blocked off, my BISS is brand new and it still wont hold boost for very long. It begins to leak out immediately after I shut off the air. Also my head is newly rebuilt with new valves, guides, seals, lifters, the works. The block is newly rebuilt with brand new pistons and rings also.

What else would cause this type of problem? I put the leak tester on my uicp right before the throttle body elbow and I'm sure the leak is not before there.

 

[oldman]

Ok, thats what I thought to begin with, so since that is true, then hearing the air escaping into the head is normal then... right?

Not exactly.

1. Turbo seal : Normal during a static pressure test as long as the turbo isn't leaking oil during operation.

2. Piston Rings : Some blow by is expected, waming up the car before the pressure test will help seal the rings better.

3. This leaves you the pcv and valves seals to worry about.

I've got my boost back but I have been unable to get it to hold it for 30 seconds before leaking out. My FIAV is blocked off, my BISS is brand new and it still wont hold boost for very long. It begins to leak out immediately after I shut off the air. Also my head is newly rebuilt with new valves, guides, seals, lifters, the works.

How much pressure were you able to pump into the intake before it starts to bleed off?

 

[RiceKiller_TSi]

Not exactly.

1. Turbo seal : Normal during a static pressure test as long as the turbo isn't leaking oil during operation.
?

I've noticed a small amount of oil in the intake but nothing significant. Just a thin film.

3. This leaves you the pcv and valves seals to worry about.

The PVC valve is less than a week old and the valve seals are supposedly brand new. I bought them myself and took em to the machine shop for the rebuild.

How much pressure were you able to pump into the intake before it starts to bleed off?

Once the pressure hits 24psi I can shut off the air and it begins to leak out after I count 2 seconds and slowly hits zero about 40 or more seconds later.

 

[oldman]

I've noticed a small amount of oil in the intake but nothing significant. Just a thin film.

If your breather valve is still routed back to the intake pipe, you will get some oil from blow by.

Once the pressure hits 24psi I can shut off the air and it begins to leak out after I count 2 seconds and slowly hits zero about 40 or more seconds later.

If 24psi was read from you're boost gauge instead of the air compressor, I would say you're done with the leak test.

 

[RiceKiller_TSi]

If your breather valve is still routed back to the intake pipe, you will get some oil from blow by.

Nah, its routed to the ground. Intake is just plugged.

If 24psi was read from you're boost gauge instead of the air compressor, I would say you're done with the leak test.

So if my boost gauge reads 24psi then I'm fine? Because I've been reading off the air compressor/boost leak detector.

Thanks for the extra help btw.

 

[oldman]

Nah, its routed to the ground. Intake is just plugged.

Then it's definitely coming from the turbo.

So if my boost gauge reads 24psi then I'm fine? Because I've been reading off the air compressor/boost leak detector.

The gauge on the air compressor usually tells you the maximum psi to release from the compressor, the boost gauge will tell you how much preesure the intake tract was actually holding.

Whats wrong with the manifold without the divider? I was actually gonna get that ring ported out of there as well and gasket match it.

The dividers are there to redirect air flow towards the turbine. Without them, air flow from different runners will end up interfering with each other, especially #1 vs. #4 runners. I usually leave the dividers alone when porting the manifold besides thinning them out.

Thanks for the extra help btw.

You're welcome.

 

[tstkl]

does blocking off the faiv have any significance? i know what depriving the faiv from coolant does, but if i just have the faiv open to the air will the car run fine, im almost posative it should be, but you never know, and also im having some major car problems, car dies at anything under 2500 rpms... dont know why...

 

[oldman]

i know what depriving the faiv from coolant does, but if i just have the faiv open to the air will the car run fine, im almost posative it should be

What exactly do you mean by open to air? VTA or just without the coolant lines hooked up? I don't see how you will be able to bring idle down to 750 even with IPS backed out and BISS screwed in all the way if you left the coolant out without blocking off the FIAV passage. Why did you remove the coolant lines anyway? What is the vacuum reading and rpm at idle? Have you done that pressure test since we last spoke? Verification of a functioning maf/maft? At least you got the car started.

 

[tstkl]

What exactly do you mean by open to air? VTA or just without the coolant lines hooked up? I don't see how you will be able to bring idle down to 750 even with IPS backed out and BISS screwed in all the way if you left the coolant out without blocking off the FIAV passage. Why did you remove the coolant lines anyway? What is the vacuum reading and rpm at idle? Have you done that pressure test since we last spoke? Verification of a functioning maf/maft? At least you got the car started.

ive tried doing a boost leak test, but i dont really have any good means of flowing a lot of compressed air... i have a bike pump that i tired, but i couldnt find anything with it (guess why...) i found out that the maft has a troubleshoot function, basically the leds, on mine they just turn on when the key is on, one then the other (i dont remember which) and then they both turn off after a while...

whats vta? i just removed the lower coolant line and re routed the upper one to where the lower one goes, and i removed them because they were preventing the throttle body from lining up with the smim, and everyone told me i didnt need them anyways...
and it doesnt idle at 2500, it doesnt idle at anything, if i start it and i dont give it gas, it will just die... i need to keep the throttle plate at about 35% to keep it alive... and if i have it sitting at 3k, and take my foot off the gas, it slowly goes down, then once it gets to 2500, it falls like a rock... i wish i could tell you the vacuum and rpm at idle, but she refuses...

yea all i have to do is cut the intercooler pipes shorter, mount the oil cooler on the side, put the bumpers on (im trying to do this without cutting the bumper at all, and it lowers the intake system volume anyways... to me its just easier this way...) and the car will be 100% done... minus whatever is causing it to not idle..... the isc is new, along with the whole ecu, from the dealer.... only one more week of football, so after that i can actually focus on my dsm and get a job so i can either tow her to paul, or get an air compressor....

 

[oldman]

Walmart has a "no questions asked" return policy and last time I checked they still sell air compressors. You must eliminate all vacuum leaks first when trouble shooting something like this.

You will also need to reconnect the coolant lines (find new hoses that will fit) because blocking off a 90 FIAV is tricky if even possible at all. You can't reroute the coolant lines and not block off FIAV because it will never close and becomes a huge open passage, or vacuum leak.

Once the FIAV situation is fixed and pressure tested to 20psi and all leaks fixed, do the following.

1. Re-adjust the IPS (Idle Position Sensor) according to FSM procedure.

2. Re- adjust TPS to the IPS.

3. Warm up the car and perform the BISS screw adjustment to set your idle to 750.

4. Set ignition timing to 5*BTDC.

Remember, you must fix all leaks first. Good luck.

 

[tstkl]

Walmart has a "no questions asked" return policy and last time I checked they still sell air compressors. You must eliminate all vacuum leaks first when trouble shooting something like this.

You will also need to reconnect the coolant lines (find new hoses that will fit) because blocking off a 90 FIAV is tricky if even possible at all. You can't reroute the coolant lines and not block off FIAV because it will never close and becomes a huge open passage, or vacuum leak.

Once the FIAV situation is fixed and pressure tested to 20psi and all leaks fixed, do the following.

1. Re-adjust the IPS (Idle Position Sensor) according to FSM procedure.

2. Re- adjust TPS to the IPS.

3. Warm up the car and perform the BISS screw adjustment to set your idle to 750.

4. Set ignition timing to 5*BTDC.

Remember, you must fix all leaks first. Good luck.

i dont understand why the faiv could cause such a big problem, could this be the root of all my problems? it is pretty weird that after replacing the smim and using all new gaskets i would have this big of a problem when i moved the maf so much closer than it was previously... i think if i just make the lower coolant line smaller it will work, that was really the only problem i believe... but everyone (paul at newlogics, dave from dejon,... etc...) told me that in a high performance car, you dont want the faiv connected to the coolant lines...
edit: i do vta (vent to atmosphere?) but i have a gm maf and maft on the upper intercooler pipe between the bov and the throttle body, so that shouldnt matter, now should it?

 

[oldman]

i dont understand why the faiv could cause such a big problem, could this be the root of all my problems? .

I don't think it's the only problem you have but it's stop one.

but everyone (paul at newlogics, dave from dejon,... etc...) told me that in a high performance car, you dont want the faiv connected to the coolant lines..

I'm sure they were assuming you will block it off instead of leaving the passage open when they gave you that advice.

edit: i do vta (vent to atmosphere?) but i have a gm maf and maft on the upper intercooler pipe between the bov and the throttle body, so that shouldnt matter, now should it?

I wasn't talking about the BOV, I was referring to your statement of "FIAV was open to air".

 

[tstkl]

well i took a look at the throttle body, and the reason why i couldnt get it to work when the coolant lines were on is because it looks something like this....(see pic) the lower line would have to be bent down below where it hooks up and the upper one really isnt long enough to make it to the other line, longer coolant lines are required. if i blocked them off would that help? i dont see how venting them would make a difference though, because the throttle body doesnt let coolant into the intake system, and thats what used to be in that chamber, so it should be sealed off, shouldnt it? if i block them off do you think this problem will be solved just as if i plugged the lines back in?

 

[oldman]

The problem isn't the coolant lines, the problem is FIAV, Fast Idle Air Valve. The valve, located in the TB stays open during cold starts to allow more air to past through (bypassing the TB Plate) in order to warm up the car faster (1500rpm). The only time the valve will close is when the coolant flowing through it reaches a certain temperature. Without the coolant lines hooked up, you must block off the FIAV passage or you will not be able to dial down your idle speed and set your TB sensors properly.

 

[oldman]

Oh, loop both coolant lines so you can properly connect them.

 

[tstkl]

Oh, loop both coolant lines so you can properly connect them.

loop them? can i just block them off? i think that would be so much easier as the ports on the throttle body are in such precarious spots... and i would have to replace both coolant lines just for them to be long enough to (im guessing this is what you ment by loop) swing around to connect to the throttle body. can i do them backwards? then I just need 1 longer coolant line i think.

 

[oldman]

loop them? can i just block them off? i think that would be so much easier as the ports on the throttle body are in such precarious spots...

You're killing me , like I already said, you can block them, leave them open to air, as long as you take apart the TB and block off the FIAV passage, you can't have it both ways. Problem is you have a 90 TB which is completely different from the 91-94 TB like described here, it would be much easier to just connect the coolant lines.

and i would have to replace both coolant lines just for them to be long enough to (im guessing this is what you ment by loop) swing around to connect to the throttle body. can i do them backwards? then I just need 1 longer coolant line i think

Look at how your coolant feed to the turbo loops around right out of the thermostate housing, same idea. How much can a piece of 3 ft. coolant line possibly cost?

 

[tstkl]

well its not really that coolant line is expensive, its that the upper line wont reach the throttle body and i didnt want to have to make a mess dealing with coolant...

anyways my friend who lives down the street from me finally called me back (hes like 23 so I dont know his scedual as he has work and stuff), he just brought over his air tank and we did a proper boost leak test, with soapy water and all, and there is a FATTY leak right between cylinder 2 and 3 on the top of the intake manifold. he says I should get a new gasket and redo it (which is what i did the first time,...) but I want to know what I did wrong the first time? there is a hole probably big enough to fit a dime, and i torqued the screws down to 14-22 ft lbs, keeping most in the 18+ range just to be safe.... is there any way i can reuse my stock, oem intake manifold gasket that has 0 miles on it (duhh the car doesnt run.... ) or do I have to buy a new one?