Tapping only under acceleration.
Thread Starter
Junior Member
Joined: Feb 2018
Posts: 90
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From: Edgewood nm
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Old fart with a wrench
Joined: Nov 2010
Posts: 14,398
Likes: 741
From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
In that case, make sure the "bumpstick" is still good. Check all the lobes with a caliper to make sure none are worn and replace the bearings. In my experience, unless you're building for a specific purpose, use a stock cam if you're going to replace it.
After all the years Chrysler has used the 4.0, they've gotten just about all the horsepower they can out of it and still kept it's longevity and EPA emissions within limits. In other words it's my opinion, don't mess with a good thing!
About the injectors, you can go to 4-holers for better atomization, but remember the PCM controls mixture by varying injector "on-time" so increased flow will be negated by the PCM. A bored throttle body will make a big difference.
After all the years Chrysler has used the 4.0, they've gotten just about all the horsepower they can out of it and still kept it's longevity and EPA emissions within limits. In other words it's my opinion, don't mess with a good thing!
About the injectors, you can go to 4-holers for better atomization, but remember the PCM controls mixture by varying injector "on-time" so increased flow will be negated by the PCM. A bored throttle body will make a big difference.
Last edited by dave1123; Feb 18, 2018 at 03:10 PM.
Thread Starter
Junior Member
Joined: Feb 2018
Posts: 90
Likes: 0
From: Edgewood nm
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
In that case, make sure the "bumpstick" is still good. Check all the lobes with a caliper to make sure none are worn and replace the bearings. In my experience, unless you're building for a specific purpose, use a stock cam if you're going to replace it.
After all the years Chrysler has used the 4.0, they've gotten just about all the horsepower they can out of it and still kept it's longevity and EPA emissions within limits. In other words it's my opinion, don't mess with a good thing!
About the injectors, you can go to 4-holers for better atomization, but remember the PCM controls mixture by varying injector "on-time" so increased flow will be negated by the PCM. A bored throttle body will make a big difference.
After all the years Chrysler has used the 4.0, they've gotten just about all the horsepower they can out of it and still kept it's longevity and EPA emissions within limits. In other words it's my opinion, don't mess with a good thing!
About the injectors, you can go to 4-holers for better atomization, but remember the PCM controls mixture by varying injector "on-time" so increased flow will be negated by the PCM. A bored throttle body will make a big difference.
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