supercharged xj troubleshooting
Thread Starter
Member
Joined: Oct 2011
Posts: 103
Likes: 0
From: Greece
Year: 1992
Model: Cherokee
Engine: l6 4.0l
After i installed the supercharger and an AEM Fi/c i started to have the following problem! When i drive for about 10 miles the jeep starts acting like the following video!
CF ADMIN

Joined: Sep 2010
Posts: 34,088
Likes: 257
From: Lantana, Fl
Year: 1996
Model: Cherokee (XJ)
Engine: 4.Slow
Search for members here named Cobramarty and boostwerks, they're the SC guys to help you out.
Last edited by Outlaw Star; Aug 16, 2015 at 12:50 PM.
CF Veteran
Joined: Sep 2010
Posts: 12,692
Likes: 6
From: Mercer County, NJ
Year: 2001
Model: Cherokee
Engine: 4.0L I6 HO
Thread Starter
Member
Joined: Oct 2011
Posts: 103
Likes: 0
From: Greece
Year: 1992
Model: Cherokee
Engine: l6 4.0l
Only map and the sensor on the intake manifold left to change!
I doubt that any sensor or map changing will make a difference.
Check for any vacuum leaks.
My kits all have a SC bypass valve to prevent compressor surge. During idle and high vacuum, the valve is open and air after the TB bypasses the SC and goes directly into the intake manifold. This keeps the SC cooler and because it is not compressing air, it free spins and uses minimal power like 3-5hp and hence doesn't cost any mpg while cruising out of boost. With low vacuum, the valve closes and all air goes thru the SC.
Still check for vacuum leaks.
Check for any vacuum leaks.
My kits all have a SC bypass valve to prevent compressor surge. During idle and high vacuum, the valve is open and air after the TB bypasses the SC and goes directly into the intake manifold. This keeps the SC cooler and because it is not compressing air, it free spins and uses minimal power like 3-5hp and hence doesn't cost any mpg while cruising out of boost. With low vacuum, the valve closes and all air goes thru the SC.
Still check for vacuum leaks.
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Do you have resistors installed for the injectors?
Wideband gauge?
I'd check the short and long term fuel trims as well. It is more than likely bouncing around trying to hone in on 14.7 but if the fuel corrections are to large it will fluctuate rich to lean causing the RPM's to fluctuate as well.
I'd honestly recommend taking it to a local tuner if possible
Wideband gauge?
I'd check the short and long term fuel trims as well. It is more than likely bouncing around trying to hone in on 14.7 but if the fuel corrections are to large it will fluctuate rich to lean causing the RPM's to fluctuate as well.
I'd honestly recommend taking it to a local tuner if possible
Thread Starter
Member
Joined: Oct 2011
Posts: 103
Likes: 0
From: Greece
Year: 1992
Model: Cherokee
Engine: l6 4.0l
Do you have resistors installed for the injectors?
Wideband gauge?
I'd check the short and long term fuel trims as well. It is more than likely bouncing around trying to hone in on 14.7 but if the fuel corrections are to large it will fluctuate rich to lean causing the RPM's to fluctuate as well.
I'd honestly recommend taking it to a local tuner if possible
Wideband gauge?
I'd check the short and long term fuel trims as well. It is more than likely bouncing around trying to hone in on 14.7 but if the fuel corrections are to large it will fluctuate rich to lean causing the RPM's to fluctuate as well.
I'd honestly recommend taking it to a local tuner if possible
Thread Starter
Member
Joined: Oct 2011
Posts: 103
Likes: 0
From: Greece
Year: 1992
Model: Cherokee
Engine: l6 4.0l
I doubt that any sensor or map changing will make a difference.
Check for any vacuum leaks.
My kits all have a SC bypass valve to prevent compressor surge. During idle and high vacuum, the valve is open and air after the TB bypasses the SC and goes directly into the intake manifold. This keeps the SC cooler and because it is not compressing air, it free spins and uses minimal power like 3-5hp and hence doesn't cost any mpg while cruising out of boost. With low vacuum, the valve closes and all air goes thru the SC.
Still check for vacuum leaks.
Check for any vacuum leaks.
My kits all have a SC bypass valve to prevent compressor surge. During idle and high vacuum, the valve is open and air after the TB bypasses the SC and goes directly into the intake manifold. This keeps the SC cooler and because it is not compressing air, it free spins and uses minimal power like 3-5hp and hence doesn't cost any mpg while cruising out of boost. With low vacuum, the valve closes and all air goes thru the SC.
Still check for vacuum leaks.
If your doing this yourself, you will need a wide band gauge. It is more than likely a fueling issue.
Have you watched the maps under real time while it does this? You'll want to know exactly what cells it is bouncing around in. If there is a large difference between those cells, it can cause this issue. It's essentially bouncing between target values
Have you watched the maps under real time while it does this? You'll want to know exactly what cells it is bouncing around in. If there is a large difference between those cells, it can cause this issue. It's essentially bouncing between target values
Member
Joined: Jul 2015
Posts: 150
Likes: 1
From: San Antonio, Texas
Year: 2001
Model: Cherokee
Engine: 4.0
Thread Starter
Member
Joined: Oct 2011
Posts: 103
Likes: 0
From: Greece
Year: 1992
Model: Cherokee
Engine: l6 4.0l
If your doing this yourself, you will need a wide band gauge. It is more than likely a fueling issue.
Have you watched the maps under real time while it does this? You'll want to know exactly what cells it is bouncing around in. If there is a large difference between those cells, it can cause this issue. It's essentially bouncing between target values
Have you watched the maps under real time while it does this? You'll want to know exactly what cells it is bouncing around in. If there is a large difference between those cells, it can cause this issue. It's essentially bouncing between target values


