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XJ Ask the Question Thread
CF Veteran
Joined: Oct 2012
Posts: 2,314
Likes: 3
From: Canton, GA
Year: 1996
Model: Cherokee
Engine: 4.0
I just installed a vacuum guage in my xj. What's the general reading for an xj at idle? Mine sat around 20 hg at idle for the couple mins I ran it. While doing this I noticed some of my fittings could use alittle love.. So that's why I'm wondering what the reading should be.
Your vacuum gauge should come with an instruction booklet outlining the procedure. Hook the vacuum gauge up to a source on the intake manifold. Start the engine and note the vacuum reading. Usually 17 to 21 inches of vacuum. Throttle the engine up to 2,000 to 2,500 RPM for 20 seconds or so and the vacuum reading should stabilize to the same reading you got at idle. Let the throttle snap shut. The vacuum reading should shoot up about 5 inches of vacuum higher for a second and then come quickly down to the original reading. If the vacuum reading stays high and comes down slowly with jerky needle movements, you have an exhaust restriction.
According to cruiser, 17-21 inches.
CF Veteran
Joined: Jul 2009
Posts: 2,522
Likes: 0
From: New Jersey
Year: 2000
Model: Cherokee
Engine: l6 HO
CRUISER’S VACUUM TEST FOR EXHAUST RESTRICTION
Your vacuum gauge should come with an instruction booklet outlining the procedure. Hook the vacuum gauge up to a source on the intake manifold. Start the engine and note the vacuum reading. Usually 17 to 21 inches of vacuum. Throttle the engine up to 2,000 to 2,500 RPM for 20 seconds or so and the vacuum reading should stabilize to the same reading you got at idle. Let the throttle snap shut. The vacuum reading should shoot up about 5 inches of vacuum higher for a second and then come quickly down to the original reading. If the vacuum reading stays high and comes down slowly with jerky needle movements, you have an exhaust restriction.
According to cruiser, 17-21 inches.
Your vacuum gauge should come with an instruction booklet outlining the procedure. Hook the vacuum gauge up to a source on the intake manifold. Start the engine and note the vacuum reading. Usually 17 to 21 inches of vacuum. Throttle the engine up to 2,000 to 2,500 RPM for 20 seconds or so and the vacuum reading should stabilize to the same reading you got at idle. Let the throttle snap shut. The vacuum reading should shoot up about 5 inches of vacuum higher for a second and then come quickly down to the original reading. If the vacuum reading stays high and comes down slowly with jerky needle movements, you have an exhaust restriction.
According to cruiser, 17-21 inches.
CF Veteran
Joined: Jul 2009
Posts: 2,522
Likes: 0
From: New Jersey
Year: 2000
Model: Cherokee
Engine: l6 HO
Herp Derp Jerp
Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
CF Veteran
Joined: Jan 2012
Posts: 8,272
Likes: 1
From: Baltimore, MD
Year: 1999
Model: Cherokee
Engine: 4.0 I6 HO
CF Veteran
Joined: Jan 2012
Posts: 8,272
Likes: 1
From: Baltimore, MD
Year: 1999
Model: Cherokee
Engine: 4.0 I6 HO
CF Veteran
Joined: Sep 2010
Posts: 12,692
Likes: 6
From: Mercer County, NJ
Year: 2001
Model: Cherokee
Engine: 4.0L I6 HO
CF Veteran
Joined: May 2012
Posts: 3,242
Likes: 2
From: Colorado
Year: 1992 Cherokee Sport
Engine: Bone-Stock 242
CF Veteran
Joined: Jan 2012
Posts: 8,272
Likes: 1
From: Baltimore, MD
Year: 1999
Model: Cherokee
Engine: 4.0 I6 HO
With my 96 im not allowed to park in the driveway. My mom yelled at me that it was ruining the driveway. Today i looked at her and said im taking my spot in the driveway back. Lolll.
Not sure exactly. I only smell it behind the jeep. Not in the engine bay. I think it could be seafoam still burning. Not 100%. Gonna drive it around a little once i get tags for it and then change the oil again.
CF Veteran
Joined: Sep 2010
Posts: 12,692
Likes: 6
From: Mercer County, NJ
Year: 2001
Model: Cherokee
Engine: 4.0L I6 HO
With my 96 im not allowed to park in the driveway. My mom yelled at me that it was ruining the driveway. Today i looked at her and said im taking my spot in the driveway back. Lolll.
Not sure exactly. I only smell it behind the jeep. Not in the engine bay. I think it could be seafoam still burning. Not 100%. Gonna drive it around a little once i get tags for it and then change the oil again.