Vacuum Leak?

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Jul 10, 2003 | 06:18 PM

goodson

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From: Gadsden AL

Vacuum Leak?

On a previous topic I outlined, that after a tuneup, My 1986 still idles rough and runs rough at low speed. The mechanic suspected the EGR valve but others idicate possible a vacuum leak. My manual gave a simple test for the PCV valve of holding a paper over the opened oil filler opening. If the paper was sucked to the opening the valve was good, if not, it was bad. I replaced the value but I still do not sense any vacuum at the oil filler opening. I did find a speed control hose that was completely in two. I replaced that - it fixed my speed control but I still don't seem to have much vacuum (at least according to the paper test) and, of course, I still have the rough idle/low speed problem. I also checked the hose connected to the PCV valve. Does this sound like I have a vacuum problem?

Jul 10, 2003 | 07:09 PM

vader86

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Re: Vacuum Leak? (goodson)

What all was replaced in the tuneup, refresh my memory?

Did you clean the IAC and TB and reset the TPS at that time?

Jul 10, 2003 | 07:32 PM

ittlfly

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From: Sun City West Az

Re: Vacuum Leak? (goodson)

Hook up a vacuum guage to the intake. You should have somewhere between 17-21 hg of vacuum if the cam is stock. Lower than that, suspect a leak.

Jul 10, 2003 | 10:27 PM

goodson

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From: Gadsden AL

Re: Vacuum Leak? (vader86)

The tune up was just replacing the spark plugs, wires, rotor button, and fuel filter. The mechanic I unfortunately used has no idea what the IAC, TB, and TPS are and just gave up on it. Truthfully, I don't know much more than he does. Being a novice, I'm a little reluctant to attack that. It requires removing the plenum doesn't it? Is this something a novice could do? The miss becomes fairly constant after the engine warms up and I notice it now up to around 45mph. It may be there after that and I just don't notice it. I thought about possibly water in the tank but that would be an ireggular sputtering wouldn't it? I was hoping it would be a simple vacuum problem I could locate and fix myself. If I don't have it figured out by Tuesday, I have an appointment with the chevy dealer. They will diagnose the problem for $55 and then I can choose whether to let them fix it or not.

Jul 10, 2003 | 11:57 PM

=Agent-Smith=

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Re: Vacuum Leak? (goodson)

I have the same problem... :mad

Jul 11, 2003 | 09:14 AM

ittlfly

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From: Sun City West Az

Re: Vacuum Leak? (=Agent-Smith=)

:lurk:

Jul 11, 2003 | 09:24 AM

grumpyvette

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From: loxahatchee fla

Re: Vacuum Leak? (ittlfly)

the way I find vacuum leaks is clean and easy with no mess. get a propane torch,

(DONT LIGHT IT) just SLIGHTLY open the valve so its allowing gas to flow at a low voluum,start the engine and let it idle at the lowest speed you can then place the tip of the UNLIT torch at any suspected vacuum leak and listen for the rpms to increase and watch the tach, gas flowing into a vacuum leak will increase engine speed. JUST USE COMON SENCE AND DON,T CATCH THINGS ON FIRE IF YOU SOMEHOW MANAGE TO GET THE TORCH LIT