Boost Leak Test Results

[ColdAudio]

Alright, just did a boost leak test and found my BOV leaking, saw small tear in line going to IM so just cut it, havent tested it since because I wanted to see from UICP after BOV to the rest of the car, now im stuck.

It only builds ~5 PSI of pressure, I can't hear any leaks at all, and there is no excessive crankcase pressure because there is no air coming out of the valve cover breather stem (the nipple on the passenger side of the valve cover, not the PCV valve)

Could the air pump I'm using not be powerful enough? Any ideas on what could be wrong/what to do next? Thanks guys!

 

[gurrmanator]

I used a bike pump and that found the big leaks but now i need a compressor so ya you need a compressor

 

[ColdAudio]

im using a small compressor at the moment

 

[ColdAudio]

ok so i did the boost leak test like everyone always says you should do, fixed a leak at the BOV thats the only one i could hear air leaking out of

at idle my vacuum is ~15-16 hg at 1100 rpm, if the rpm dip down to 900 the vacuum ~10 hg. im assuming this is a vacuum leak, also because from the TB my car could only build 5 psi during leak test.

my question is this: now what? how do i figure out where the leak is if there is more, do i need to do compression test, etc? also, occassionally when i hold my car at 2k rpm in neutral the exhaust sounds like its popping popcorn, could this be related at all, if not what would cause this a miss?

sorry im so full of questions! i absolutely love this car and am always willing to put as much time as i need to into it, but cant without at least a direction to go in. for the few who have been watching my newbie question filled threads, i fixed everything else (the fuses and rad fan problems), and this is one of the last maintenance things i need to take care of. any and all help is greatly appreciated, and needed! thanks a ton for those of you who take the time to reply.

 

[oldman]

1. What size compressor? Maximum psi?

2. Did you spray soapy water all over the TB, intake gasket, injector seals and all vacuum hoses?

3. Remove the oil cap and stick your ear in there during test and listen for leaks.

4. Stick your ear in the tail pipe and listen for leaks.

 

[styx]

you have a 1991 motor replace the injector insulators i gurantee if stock they are shot

 

[ColdAudio]

you have a 1991 motor replace the injector insulators i gurantee if stock they are shot

and what makes you say that?

and oldman ill get to it as soon as i get home, i forget what max psi is on compressor it is like 150 or something, it fills tires and stuff quite nicely, but its small so i doubt its very powerful, thanks for the replies guys

 

[styx]

and what makes you say that?

and oldman ill get to it as soon as i get home, i forget what max psi is on compressor it is like 150 or something, it fills tires and stuff quite nicely, but its small so i doubt its very powerful, thanks for the replies guys

plenty of experience says that, gurantee they are hard as plastic if they are the originals, no if and or buts, that old they are shot

 

[ColdAudio]

ok well since this is the first car ive ever done anything myself on, and refuse to do it otherwise, what do they look like and how do i take em out?

 

[Strm Trpr]

First thing I'd do is allow your car to idle with the fuel pump power unplugged from the pump.
Remove your PCV valve.
Then, there are 3 screws that hold the fuel rail on.
Lossen those and do not I repeat do not let the little black plastic spacers fall.
These spacers are there to stand-off the rail to the head, without them you'll crack the fuel rail when you reinstall the rail.
Once the rail is able to lift up, you'll be able to pull the injectors out.
Have a rag handy, some fuel may still be in the system.
There are 12 seals all together, 3 per injector.
There is a seal that goes into the head, then there are some seals called sheets, then there are some little o-rings that seal the injector into the fuel rail.
You can order them from Mitsu, or Mach V has a new set.

http://www.dsmtuners.com/forums/showthread.php?t=104301

 

[oldman]

There are 12 seals all together, 3 per injector.
There is a seal that goes into the head, then there are some seals called sheets, then there are some little o-rings that seal the injector into the fuel rail.
You can order them from Mitsu, or Mach V has a new set.

There is no need to pull the injectors out of the fuel rail, remove the rail and the injectors slowly so everything comes out in one piece, the bottom four seals/insulator between the injectors and the head are what you need to worry about. I do however do not recommend that you pull them until you're sure they're leaking, you'll know if they are once you spray soapy water on them.

 

[ColdAudio]

alright cool thanks for the advice guys, ill follow your steps oldman, but i think im workin OT and wont be home for another 9 hours, ill update then


*EDIT* forgot to mention my air pump is extremely loud and probably isn't allowing me to hear any small leaks. will soapy water show everything, or should i use a hand pump?

 

[oldman]

will soapy water show everything

It will bubble if there is a leak.

 

[styx]

There is no need to pull the injectors out of the fuel rail, remove the rail and the injectors slowly so everything comes out in one piece, the bottom four seals/insulator between the injectors and the head are what you need to worry about. I do however do not recommend that you pull them until you're sure they're leaking, you'll know if they are once you spray soapy water on them.

word up with what old man says on how to replace them

 

[sherwinz28]

Anyone know where I can buy a boost leak tester. I went to Lowes and Home depot to see if they carried the correct hoses and they didn't...I'm tired of driving around trying to find the parts.

Thanks,
Sherwin

 

[styx]

Anyone know where I can buy a boost leak tester. I went to Lowes and Home depot to see if they carried the correct hoses and they didn't...I'm tired of driving around trying to find the parts.

Thanks,
Sherwin

you don't have to use the expensive hose as seen on vfaq any type of rubber hose that is that size/diameter will work fine. now if you plan on pushing 500psi i would recommend the hose type used on vfaq

home depot will definiantly have something you can piece together.

 

[oldman]

PVC pipe rubber couplers in the plumbing department.

 

[ColdAudio]

ack i hate to say it but im not going to have time to re-do testing for at least a few days, im more busy during the summer than the school year! ill bring this post back up when i get some free time for testing

 

[ColdAudio]

**UPDATE**

So, today I finally had time to give the boost leak test a shot again following your instructions oldman and here's what I came up with.

Did not hear any air leak from valve cover with oil cap removed and did not hear any leak through exhaust (although that itself leaks)

Pressurized whole system with same small pump got ~2 psi at turbo and ~4-5 psi at TB Elbow. Did not hear any leaks, sprayed all vacuum spots (gaskets, hoses, etc) with soapy water 1 by 1 and none showed signs of leaking.

So I have come to the conclusion that either:
1. My small pump is not nearly strong enough to actually find any leaks.
2. There is a problem with vacuum other than boost leak test can find, maybe bad timing?

Vacuum is ~15 hg at ~1.2k idle but if the idle drops to ~1k then the vacuum also drops, to about ~10-12 hg. It drops very rapidly, and the idle will come back up to compensate for the lost vacuum, thus ocassionally also causing idle surge.

Also, my alternator is messed up I believe it's the belt, when I have the lights on and turn on my signal everything starts flashing. Can this affect my vacuum issue at all?

What to do next, any more detail needed? All help is appreciated, thanks!

 

[Cool Mr Steve]

Man, that sucks... I'm having low vacuum issues too that I can't figure out. Did you try to test for vacuum leaks at your hoses? With the car running, spray something explosive (I used a propane torch minus the flame, I've heard Carb Cleaner works...) in your bay around where there could be vacuum leaks (hoses, TB, etc) and listen for a change in idle. As for your possible boost leaks, I tried using a "portable compressor" a few times (the kind that you plug into your cigarette lighters... They may be able to compress up to 150 psi, but it's over the course of 5 days...) but you really need something that will be able to fill up your system with a little more vengeance. Also, I'm not sure what your exact setup is, but I had a pretty large leak at one of my intercooler couplings that was barely audible, but caused major issues.

 

[oldman]

1. My small pump is not nearly strong enough to actually find any leaks.

 

[ColdAudio]

I'll see if I can find someone to borrow a like 2-3 gal compressor from... that thing I'm using takes 10 minutes to fill a pool float!

Off topic, but how do you know when to change timing belt?

 

[oldman]

Off topic, but how do you know when to change timing belt?

Mostly by milage, it should be changed every 50-60k miles.

 

[ColdAudio]

Mostly by milage, it should be changed every 50-60k miles.

Hmm, I have no idea when the last owner did it, does it ever show signs of wear? Can't really afford new belt at the moment...

 

[RamenPride]

Hmm, I have no idea when the last owner did it, does it ever show signs of wear? Can't really afford new belt at the moment...

a trashed head from a broken belt will cost you more....