1990 4.0l slow to start and rough idle
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Joined: Apr 2016
Posts: 1,820
Likes: 60
From: Pasquotank, NC
Year: 1990
Model: Cherokee
Engine: 4.0
I drove the Jeep to church this morning, ran great! It's still not 100%, but it is close. I think the idle issue last night was burning throttle body cleaner out. Started it this morning and there was no high idle issue. Still a slight surging idle, but no Jeep shaking. I printed out the section of the FSM for testing all of the sensors, will run through those next. Also plan to replace the injectors as I am unsure of their condition and it's a good excuse to upgrade to the 746s.
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Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
I drove the Jeep to church this morning, ran great! It's still not 100%, but it is close. I think the idle issue last night was burning throttle body cleaner out. Started it this morning and there was no high idle issue. Still a slight surging idle, but no Jeep shaking. I printed out the section of the FSM for testing all of the sensors, will run through those next. Also plan to replace the injectors as I am unsure of their condition and it's a good excuse to upgrade to the 746s.
Thread Starter
CF Veteran

Joined: Apr 2016
Posts: 1,820
Likes: 60
From: Pasquotank, NC
Year: 1990
Model: Cherokee
Engine: 4.0
Have been driving it daily to work for the past week. It drives and idles smooth about 30% of the time. Occasionally the RPMS go up to 1000 in gear, and drop to 400 in gear.
Installed a set of the 746s tonight. A spin around the block revealed a smoother idle, improved throttle response. I'll see if I get better mileage this tank full, last couple have been 13.2 mpg. Something is still not right, has an intermittent issue still.
Installed a set of the 746s tonight. A spin around the block revealed a smoother idle, improved throttle response. I'll see if I get better mileage this tank full, last couple have been 13.2 mpg. Something is still not right, has an intermittent issue still.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Have been driving it daily to work for the past week. It drives and idles smooth about 30% of the time. Occasionally the RPMS go up to 1000 in gear, and drop to 400 in gear.
Installed a set of the 746s tonight. A spin around the block revealed a smoother idle, improved throttle response. I'll see if I get better mileage this tank full, last couple have been 13.2 mpg. Something is still not right, has an intermittent issue still.
Installed a set of the 746s tonight. A spin around the block revealed a smoother idle, improved throttle response. I'll see if I get better mileage this tank full, last couple have been 13.2 mpg. Something is still not right, has an intermittent issue still.
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