Hey guys, I've recently been on an escapade where every vacuum line I touch breaks in my fingers.. So, we had some left over lines from our project car, I decided to re-do all of them.. I did around the coil, and a few going to the TB. I decided to do a test, to see how much vacuum I actually had, turns out it's around 5psi. What is it supposed to be at? Thanks, KP.

 

Vacuum is usually measured in in/hg or in/h2o, not PSI.

There is a PSIA measurement, that is in an area that is considered "vacuum", but is more related to the discussion of atmospheres than vacuum.

What did you use for measuring, and where did you connect the gauge to?

 

it was in/hg.. The tester had PSi on it, and that's all I could remember.. Too many beers today.. Anyway, it was 5 in/hg.. Thanks, KP.

 

No its not normal. The proper range is 17-21 in/hg at idle. Even 17 in/hg is kind of low. Are they're any open sources of vacuum? Checking vacuum is a good engine condition test, assuming all your lines and intake manifold gaskets are in good condition. Vacuum is created by pistons pulling in air through the intake, with the throttle restricting air. If you snapped the throttle to wide open you should theoretically go to 0 in/hg. Check all your lines and connections. A good way to check is by using carburator cleaner around intake gasket surfaces and vacuum fittings. Some people dont like this method because they think it may cause an engine fire, and it actually can, but most likely wont if your not a jerk with the can and dont spray it on your exhaust. You would be listening for a change in idle. I'm guessing your car is running like crap if it has 5 in/hg.

 

Actually it doesn't run too bad at all. I'm getting an average MPG of 28.. It's just slow.

 

Where did you attach the vacuum gauge?

It should be attached to a port on the plenum, to check for engine vacuum.

 

There's a vacuum line going from behind the intake to a little valve on the exhaust manifold, thats what I put it.

 

kevin, bro... dude... buddy-man guy....are you getting 28Mpg, or 28 Kpg???

i dont want you to spray any cleaner on anything ....unless you are cleaning it. Get a map or propane torch, sans the flame. start the car, open the valve on the torch now all those vac hoses and what not poke em with the bottle..lol easy with the tip but when the rpm jumps, there your sign!

are you still getting winter fuel? if you are getting 28 miles, not klm that is f n great! and i would not mess with what ever your vac leak is but you could check and share with the board!

bill

 

If it's the one that I'm picturing, then you are hooked up to a ported vacuum source, not a manifold source. Hook up to the fitting on the rear of the upper manifold and you'll get a more accurate reading.

 

I'm getting roughly 12km/liter, It calculated out to around 28MPG.
Oh, and my SES light hasn't been coming on anymore (touch wood) I changed a line going under the intake plenum, and added new plug wires. It's a crapshoot with this car..

 

Hey all, just an update. My SES light has been gone for a while now. I checked my timing, it's at 15* at startup, and slowly itches down to 11*. Seems to be running good, idles at 500 RPM. Thanks, KP.