I can't shake this vacuum leak need help please!

[Jiggalude]

Alright so this happy little mess of stuff below is what I removed my Vac. lines from. I've had an ongoing issue with only getting about 14/16 lb/hg. at idle and now we're down to about 9 or 10 I'd say, and not to mention the car is leaning out pretty nicely for obvious reasons. I have a boost leak tester, and it leaks down slowly, until it gets to about 5 PSI and then it takes a bit more to leak out. I'd say about 30 seconds from 15 psi or so to 5, and then another minute or so for the rest. But anyway, would removing and capping these vac lines, (on a 1g on drivers side firewall, right above the master cylinder) cause a vac leak? I know that they attached to two nipples underneath the intake manifold.

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[BLINKY619]

wow to me thats a boost leak i mean mine holds for a couple of minutes..... also in my 2g i found out that one of my sensors was leaking... i could hear it with the blt...!!

 

[RiGs2G]

Maybe its the view, but those sensors dont seem to be hooked up to anything but themsleves? on my 2G, I havent had those sensors hooked up for years and dont have any problems. Im going to say that these sensors arent causing your lean issue. A good way to check for vaccum leaks is to get a can of carb cleaner and spray around the throttlebody, if the car stumbles when sprayed, that is where your leak is. The main vaccum leak areas are the TB and the intake manifold, check there.

 

[steve]

Looping the solenoids is a waste of time. They are disconnected and can be left open.
Since it's a 1G you can even remove them but you need to seal the connector if you do so that water can't get in it and short out the pins blowing the ECU drivers.

 

[Jiggalude]

Ok, I figured I could leave them unplugged, but I rerouted them into themselves just in case. Yea I think my TB is still leaking even after I replaced the O-rings. So I took it off again and redid the o-rings. I only said it was a vacuum leak because I'm getting such low lb/hg like 9 or 10. I did a boost leak test and when my boost gauge gets to about 15 psi it starts hissing loudly from the TB. Would this cause low vacuum also?

 

[fullCircle]

Ok, I figured I could leave them unplugged, but I rerouted them into themselves just in case. Yea I think my TB is still leaking even after I replaced the O-rings. So I took it off again and redid the o-rings. I only said it was a vacuum leak because I'm getting such low lb/hg like 9 or 10. I did a boost leak test and when my boost gauge gets to about 15 psi it starts hissing loudly from the TB. Would this cause low vacuum also?

yes, you need a tight seal to get good vacuum.

it's like sucking soda through a straw with a pin hole in it. it gets the job done, but takes longer to drink it.... not too mention it sucks (or the lack of)

 

[mcneilmg]

yes, you need a tight seal to get good vacuum.

it's like sucking soda through a straw with a pin hole in it. it gets the job done, but takes longer to drink it.... not too mention it sucks (or the lack of)

FullCircle is completely correct. A engine is nothing more than a giant aircompressor. The system must be completely sealed. I would ponder to say to replace the gasket that is between your TB and the IM. Evenly torque the bolts without over torquing and hopefully this will solve the leak. Good luck

 

[Dsm4lyfe12]

+1 there both very correct.

 

[And_44]

Make sure the ports that you unplugged on the Throttle body are capped as well. And the remaining vacuum hoses have been replaced with new. But yes a hiss isn't good from the TB.

 

[fullCircle]

one more thing you might want to check into is doing a compression test and leak down check on the engine cylinders. check the overall condition of the internals.

 

[Jiggalude]

Just did a compression test two weeks ago, compression was fine. It was coming right of the TB, once it got to about 15 psi like I said, I could hear it rushing right out.

 

[Jiggalude]

Well, I fixed the TB leak, IC pipe leak, valve cover leak, fuel injector O ring leak, and I still am leaking 20 psi in under a minute. To be fair the last 10 psi or say takes a while to bleed out, but I'm still losing that 10 psi quickly. So, what else would be leaking other than my intake manifold gasket? I'm assuming the previous owner, who recently rebuilt the head, put everything back together hastily. I can't really seem to hear it leaking either.

Well for an info. bump. I put the car as close to 30 degrees above TDC. I found a couple more leaks at my IC pipes, but at idle I'm still only getting at most 14 lb/hg. When I pump my brakes the vacuum will go lower and I will lean out off the chart of my AFR gauge. Also, When the car has sat over night and I start it the next day it will smoke for probably a good 5 minutes or so. The previous owner told me he had just had the head rebuilt, and I took the valve cover off and it looked very new and clean. So, assuming he actually did rebuild the head and the valve seals aren't the problem, what else would cause the smoking, just the turbo? Also it doesn't smoke the entire time, and I don't see any oil or feel any shaft play in the turbo.

 

[fullCircle]

I would get a hold of a cylinder leak down tester. this is different than a compression tester. here is a link on what it is and how to use it. by no means take it personal if you know what it is and how to use it... this may help somebody else that doesn't and is looking for answers.

Cylinder Leak Down Testing
How to Use a Cylinder Leakdown Tester
From the April, 2009 issue of Car Craft

How to do Cylinder Leak Down Testing- Car Craft Magazine

 

[steve]

Clamp off the brake booster hose from the intake manifold and see what happens. Same for the PCV hose if your still using it.

 

[ramsack]

test your pcv valve, old ones are good sources of a vacuum and boost leak, and if it's leaking vacuum, it will leak like hell.

 

[Jiggalude]

test your pcv valve, old ones are good sources of a vacuum and boost leak, and if it's leaking vacuum, it will leak like hell.

Well I have the PCV valve off the car completely now. There is nothing there but the hole with the threads in it. However, I do have the nipple on the intake manifold blocked off, so there shouldn't be a leak there. How usual is it for the vacuum line to the master cylinder to be leaking?

 

[steve]

Usual? Not very but it happens.